Results 1 to 98 of 98
  1. #1
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87

    Chain skipping and falling off

    I have a problem with chain skipping on my Dean Colonel 29er. It’s got about 250 miles on it. The drive train is Sram X0 in back and Shimano XT in front with X0 shifters. When I’m really torquing the cranks while I’m on the center chain ring and on about the third to fifth sprocket (from the inside) in back and I hit some rough trail that bounces the rear end, the chain skips. The skip seems to be at the front, not the back. Worse than that, at least three times when I’ve been pushing up a short hill in those gears, the chain has come off and fallen on the bottom bracket inside of the smallest chain ring. The front derailleur will still be positioned on the middle ring.

    Thinking that the front derailleur might be out of adjustment, I’ve increased cable tension so that the chain will barely drop from the large to middle, but that didn’t help. The chain length seems spot on. Large to large has the rear derailleur stretched so that the chain is almost going straight through the pulleys.

    Any suggestions?

    Thanks.

    ChuckD
    Last edited by Monument247; 07-24-2006 at 08:04 PM.

  2. #2
    Over the Hill
    Reputation: dstepper's Avatar
    Join Date
    Feb 2004
    Posts
    1,751
    This won't address all the problems you are having. My 5-Spot was dropping the chain off the granny onto the frame. In rock gardens had to stay in middle ring to keep tension on chain.

    Tried this and has worked well http://www.ajsbikeparts.com/web-AJBIKEPARTs/AJ's Frameguard.htm

    Now the skipping sounds like a weak spring in rear derailleur...borrow another derailleur...see if it helps.

  3. #3
    mtbr member
    Reputation: Martin6's Avatar
    Join Date
    Jul 2006
    Posts
    347
    I had this same problem and it was driving me crazy. I ended up replacing the middle chain ring and it solved the problem.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Oct 2004
    Posts
    3,061

    Just curious...

    Quote Originally Posted by Martin6
    II ended up replacing the middle chain ring and it solved the problem.
    What was wrong with the old middle ring that caused it to skip and fall off? Just worn out? Bent? Missing teeth? Something else?

  5. #5
    mtbr member
    Reputation: Martin6's Avatar
    Join Date
    Jul 2006
    Posts
    347
    Kevin,

    I couldn't visibly see anything wrong with the old chain ring besides just normal wear. The bike only had a dozen rides on it at the time. I had already replaced the chain and cassette with no luck. It wasn't until I put the front tire against a wall and applied pressure on the pedal that I could see the chain was slipping on the chain ring. This is on an 06 Epic Marathon.

  6. #6
    mtbr member
    Reputation:
    Join Date
    May 2006
    Posts
    3
    For the front derailleur you will need to adjust the low limit screw in order to get the derailleur cage to keep the chain on.

    Try swapping out the rear deraileur, your chain could also be too long but I doubt that would be the case on a new bike.

    hehe.. I'm so used to being in a shop when giving advice not trying to diagnose over the Internet

  7. #7
    mtbr member
    Reputation: Martin6's Avatar
    Join Date
    Jul 2006
    Posts
    347
    Quote Originally Posted by Popps
    For the front derailleur you will need to adjust the low limit screw in order to get the derailleur cage to keep the chain on.
    Good advise. I did make the adjustments to the front derailleur as Popps suggests, because I was having the same problem of the chain falling to the BB when it would slip. All is good now.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    I got some good news today, in a way. It seems that my problem is a known problem with the new Shimano XT middle ring shift ramps. They advise using an LX middle ring until they work out a fix.

    Thanks to everyone for the replies.

    ChuckD

  9. #9
    Soft AND Tender
    Reputation:
    Join Date
    Jun 2005
    Posts
    140
    Monument247,

    Can you elaborate on the "problem" with new XT middle rings? I just put a new one on and experienced the skipping thing this weekend when riding.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    46

    Porblems with LX chain rings also

    Just a head's up, I had a brand new LX crank and chain rings on my brand new bike, and had the same problem, every thing was brand new. I finally replaced the middle chain ring with a Tru Vativ and have had no other problems. The point is that the new LX middle chain rings may have problems as well. At least I had problems with mine.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    redclayrambler - Where did you get the Truvativ ring? What did it cost? I see one at Jenson for $24.48.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Any compatibility issues with the Truvativ middle ring in between Shimano chain rings?

    Also, for everyone here having this skipping issue, what chain are you running?

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jul 2006
    Posts
    12
    Quote Originally Posted by redclayrambler
    Just a head's up, I had a brand new LX crank and chain rings on my brand new bike, and had the same problem, every thing was brand new. I finally replaced the middle chain ring with a Tru Vativ and have had no other problems. The point is that the new LX middle chain rings may have problems as well. At least I had problems with mine.
    Yup same here, same exact problem with a brand new LX crankset. Switching from and 8-speed to 9-speed chain seems to have helped the problem a LITTLE bit, but it's still happening. I'll be replacing the rear derailleur soon (it's ten years old, and a little worn out), and the middle chainring if that doesn't fix it.

    edit: Ok, I just got off the phone with Shimano. They confirmed that this is a known problem with the XT chainrings, but that my case is the first they've heard involving LX chainrings. The guy was a little suprised, since they've been sending out LX rings to the affected XT owners, which seem to be fixing the problem (BTW, the new chainrings are free under warrantee).
    Last edited by tick; 07-26-2006 at 03:52 PM.

  14. #14
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    cbratt - The problem is pretty well explained in the initial post.

  15. #15
    MTB B'dos
    Reputation: LyNx's Avatar
    Join Date
    Oct 2004
    Posts
    21,279
    Actually I find the best and cheapest replacement is an old Deore middle ring, they're string as hell and cheap. I had to do the same thing with the middle ring on my RF RideXC cranks when I first got my bike with them. Also had to replace the Shimano XT HT2 middle ring when I got that in only amonth or so, but that I think was due to a worn chain, but it did tend to "fall off" before it started skipping.
    One day your life will flash before your eyes, will it be worth watching??

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jul 2006
    Posts
    12
    Well I just got back from my LBS... I explained the problem with the middle ring to them, and got them to call Shimano to verify that this is a known issue. I should have my (free) replacement chainring from Shimano in a week or so . If this doesn't work, then I'll buy a middle ring from a different manufacturer. No sense in spending money on a new chainring for a brand new crankset, right?

  17. #17
    mtbr member
    Reputation: Martin6's Avatar
    Join Date
    Jul 2006
    Posts
    347
    Ok, I just got off the phone with Shimano. They confirmed that this is a known problem with the XT chainrings, but that my case is the first they've heard involving LX chainrings. The guy was a little suprised, since they've been sending out LX rings to the affected XT owners, which seem to be fixing the problem (BTW, the new chainrings are free under warrantee).
    Thanks for the heads up on the warrantee from Shimano. I'll make the call tomorrow for a new chainring.

  18. #18
    surly and rigid
    Reputation:
    Join Date
    Apr 2004
    Posts
    43
    Just a quick note. Most other rings aside from shimano will not work great on a shimano crankset. Watch the spacing. Good luck

  19. #19
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    46
    Any compatibility issues with the Truvativ middle ring in between Shimano chain rings?

    Also, for everyone here having this skipping issue, what chain are you running?
    redclayrambler - Where did you get the Truvativ ring? What did it cost? I see one at Jenson for $24.48.
    I got the chain ring from a local bike shop, and I think it cost about twenty something.
    I was not sure at all if the Tru Vativ would play nice with the other Shimano stuff, but the guy at my shop said it should not be a problem, and he was right it seems to work just fine.
    Unfortunatey I don't know what model Tru Vativ ring it is, but they were both 32 tooth with shifting ramps.
    Hope that helps.

  20. #20
    mtbr member
    Reputation:
    Join Date
    Feb 2004
    Posts
    594

    same exact issue here

    Monument247, did the LX middle ring fix the problem? This is driving me crazy too.

    On my Turner FLux I have a brand new 32T XT middle ring (M760 crankset) and I am having the exact same issue described in your original post. The combination of being in the middle ring, 3rd to 5th cog , bumpy terrain, and applying serious torque to the pedals results in a horrible grinding/popping. If I can, I try to look down to see the trouble while it is occuring and I have seen the chain halfway off of the middle ring even though I never shifted. The grinding noise is the chain trying to climb back up onto the middle ring while under torque.

    I have checked the following:
    -New SRAM PC 990 cassette
    -New SRAM PG 991 chain
    -New Shimano XT 32t middle ring
    -Chainline when in the middle ring and middle cog is straight
    -One BB spacer on the drive side with Shimano M760 crank set + 73mm bb shell
    -In my big ring / big cog combo my rear derailleur is stretched tight, but I can shift into this big/big combo without blowing things up
    -checked for stiff chain link
    Eat Food. Chop Wood. Ride Bike.

  21. #21
    mtbr member
    Reputation:
    Join Date
    May 2006
    Posts
    12,015
    I just mounted a XT hollow tech II crankset. I had some issues setting up the FD.

    I was surprised but had to lower the FD about 3mm to match the shimano spec of 1-2 mm clearance. The old cranks were Race face.

    Problems went away.

  22. #22
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    Dave in Driggs wrote: "Monument247, did the LX middle ring fix the problem?"

    I don't know, yet. I don't think that I'll see the replacement ring until next week. I'm confident, though, that it'll fix the problem. Why don't you call the place you bought the bike and get them to call Shimano for a replacement ring? It sure sounds like you have the same problem. While waiting, my temporary solution is to run on the small ring with the rear on the outer sprockets which gives me similar ratios. No skipping problems that way.

    jeffscott - The XT derailleur comes with something called a Pro Set alignment block to set the gap, so I don't think that spacing is causing this particular problem.

    Thanks for your input.

    ChuckD

  23. #23
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Monument, what chain are you running? It seems that most people with this problem are running SRAM chains on XT cranksets. I'm trying to figure out if trying a Shimano chain would solve the problem without having to go to an LX middle ring.

  24. #24
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    51
    I seem to have the same problem with my Shimano 9 speed chain on my XT middle ring. Everythings pretty brand new. Otherwise the index shifting is nicely dialed in. I get the skip when heavily torquing with no shifting being attempted -- usually while motoring down an easy trail and suddenly coming upon some short, steep techy section. Expecting an LX ring to try next week. I've been making a point of staying in the smallest chainring more often to avoid occurances.

  25. #25
    mtbr member
    Reputation:
    Join Date
    Feb 2004
    Posts
    594
    Quote Originally Posted by jcbikeski
    I seem to have the same problem with my Shimano 9 speed chain on my XT middle ring. Everythings pretty brand new. Otherwise the index shifting is nicely dialed in. I get the skip when heavily torquing with no shifting being attempted -- usually while motoring down an easy trail and suddenly coming upon some short, steep techy section. Expecting an LX ring to try next week. I've been making a point of staying in the smallest chainring more often to avoid occurances.
    Which chain are you running?
    Eat Food. Chop Wood. Ride Bike.

  26. #26
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    51
    HG93 I think is the model number of the chain. It's the XT (and XTR?) one

  27. #27
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    Sram PC 951. Shimano says it's a problem with the shift ramps. I think that, if it is indeed happening with a lot of Sram chains, it's just because they're very popular. I'll know any day now when my chain ring gets here.

    ChuckD

  28. #28
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by Monument247
    Sram PC 951. Shimano says it's a problem with the shift ramps. I think that, if it is indeed happening with a lot of Sram chains, it's just because they're very popular. I'll know any day now when my chain ring gets here.

    ChuckD
    I think you're right. The Shimano support rep I talked to didn't even ask me what chain I was running and simply promised to send me an LX middle ring. Shimano would blame SRAM if they could, so it seems to me that the problem lies in the middle ring regardless of the chain being run.

  29. #29
    mtbr member
    Reputation: 2gunnz's Avatar
    Join Date
    Jun 2006
    Posts
    116

    how far back

    Does anyone know how far back they are covering the chainrings? I have a 2004 giant vt2 that has the same problem everyone is describing.

  30. #30
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Did the VT2 even come with an XT crankset? The new shift ramps were a very recent change to the XT chainrings, so your bike is probably suffering the same symptom caused by a different problem, such as worn or bent chainrings. Have you changed your chainrings since you bought the bike 2 years ago? If not, this would be a good place to start.

  31. #31
    mtbr member
    Reputation:
    Join Date
    Oct 2004
    Posts
    3,061
    Quote Originally Posted by 2gunnz
    Does anyone know how far back they are covering the chainrings? I have a 2004 giant vt2 that has the same problem everyone is describing.
    FWIW, I put a new XT crankset on my bike about a year ago. I didn't have this particular chain skipping problem mentioned by the OP and others, but the middle ring did wear really fast - it only lasted one chain and I'm careful about checking for chain wear. (I replaced it with a Race Face ring which is still working well.)

    I agree with TLud on this matter... if you haven't changed the ring since you bought the bike, it's probably just worn out.

  32. #32
    mtbr member
    Reputation:
    Join Date
    Aug 2004
    Posts
    15

    XTR chainrings are no better

    This is happening on XTR stuff as well. Just put an entire new drive train on the '04 Blur (Sram 990 cassette, Sram 991 chain, Sram x-9 deraileur, new xtr middle chainring, new bottom bracket, new free wheel assembly - and of course all new pivot points) and this problem just started. The LBS is requesting another XTR chainring as they too think this is the problem.

    Nothing like expecting the bike to ride like new and then having this nasty problem start up.

  33. #33
    mtbr member
    Reputation:
    Join Date
    Feb 2004
    Posts
    594

    Update

    I posted this over on the Turner forum as well.

    Turner recommended I try moving the drive-side spacer over to the non-drive side (M760 crankset) despite what Shimano says. They also recommended that I ditch the SRAM chain for an XTR and make sure my b-tension screw was adjusted properly.

    I made all three changes at once but I did leave my like-new XT middle ring on and I haven't experienced the popping/grinding since. I have a section of trail that was causing the problem every single time I rode it and I have ridden it three times since making the change with no issues. Woohoo!
    Eat Food. Chop Wood. Ride Bike.

  34. #34
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    51
    I read a lot about how things like a crank spacer can affect the chainline and thus this problem, but at least in my case it's hard to see how a couple millimeters in or out of the chainring from the frame would matter. I've seen the problem with the rear in a middle-ish gear and the difference between two rear gears is more than a spacer on the crank. Also in my case the front deraileur seems well centered over the middle chainring so it's not gently trying to push the chain off. So a chainline being a little off would seem to affect more extreme gears more than the middle ones that are the problem.

    I have a shimano chain so it's not the potential SRAM chain issue. I have no stuck links. I've read that loose pivots can affect this, but all seems very solid. My RD hanger seems straight. I can't see how chain tension would be involved since the problem happens in the middle chainring and not the smallest one and anyway experiments showed removing one more link pair made the link too short.

    I do suspect it relates to the shock compressing while torquing hard on the peddles, but not sure what to do about that notion.

    I still need to try the LX chainring to see if that helps like some have suggested.

    Anyway, for now if I'm careful to avoid the middle ring when doing anything other than cruising then all is good.

  35. #35
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87

    New ring, not fixed.....

    The FedEx person delivered my new middle ring today. I installed it and took my usual desert ride. The short slow climbs worked perfectly where the chain skipped or fell off before. I was happy. At my turnaround point, there's a downhill section then uphill. Nothing steep. I went down and picked up speed and stood and torqued the pedals on the uphill. I deliberately rode over rocks to bounce the rear end and the chain skipped on each pedal stroke. I turned around and went back and tried it again. It happened again. At the end of the ride, I went down a road that has a quick downhill followed by a steep uphill. You try to maintain momentum and clear the hill by staying in a larger gear and standing going up to clear the top. It's bumpy and the chain skipped again. Problem not solved - just different.

    I looked closely at the two rings tonight and, if I didn't know better, I think they sent me another XT ring. The markings are identical except one says EC and the other ED. The old one's black and the new one is silver. They both say m9 S-32. Is it possible that they sent me another XT ring by mistake? There's a picture below if I did things right.

    Thanks.

    ChuckD
    Attached Images Attached Images

  36. #36
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    3
    I'm a LBS owner having the same issue. Having the problem with my XTR Crankset (middle) and XT Crankset (middle). Shimano said there is an issue with Middle XTR, XT, LX rings. I just replaced mine today with race face (on my XT crank) at first I thought it was problem solved but had another issue up rocky climb on my test ride. It doesn't seem to matter if it's on my hardtail or FS. I did mess with the B tension screw(all the way screwed in) this helped some.
    I've be working in the bike business for 15 years, and I'm stumped.
    This is my set up
    SRAM X9 Rear Derail
    SRAM PC99 Chain
    XT Crank with Race Face Rings
    Also both bikes are 29....how bout everyone else.

  37. #37
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    Twitches - So, the Race Face wasn't the solution? Have you tried a Shimano chain? I'm using a Sram, but I'm thinking about trying the Shimano chain from my Fisher Piranha. The problem bike is a Dean Colonel 29er. Since you have a Shimano contact, are they recommending any workarounds?

    ChuckD

  38. #38
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    3
    From what I hear the problem is more with 29ers. I'm going to try my shimano chain with the race face rings. I'll post the results later.

  39. #39
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    46
    From what I hear the problem is more with 29ers. I'm going to try my shimano chain with the race face rings. I'll post the results later.
    Like I posted earlier my chain skipping problem seems to have been fixed by changing out my LX ring (brand new ring and drive train) for a Tru Vativ ring. But it's interesting that my bike is a 29er also, could this be because of having to use more chain with the longer chain stays?
    I really don't think that should matter much, I don't hear much about this on the 29er forum.
    Any way hope you get it fixed

  40. #40
    WIRVNTANASHRSH?
    Reputation: climr's Avatar
    Join Date
    Oct 2005
    Posts
    228
    Quote Originally Posted by Monument247
    The FedEx person delivered my new middle ring today. I installed it and took my usual desert ride. The short slow climbs worked perfectly where the chain skipped or fell off before. I was happy. At my turnaround point, there's a downhill section then uphill. Nothing steep. I went down and picked up speed and stood and torqued the pedals on the uphill. I deliberately rode over rocks to bounce the rear end and the chain skipped on each pedal stroke. I turned around and went back and tried it again. It happened again. At the end of the ride, I went down a road that has a quick downhill followed by a steep uphill. You try to maintain momentum and clear the hill by staying in a larger gear and standing going up to clear the top. It's bumpy and the chain skipped again. Problem not solved - just different.

    I looked closely at the two rings tonight and, if I didn't know better, I think they sent me another XT ring. The markings are identical except one says EC and the other ED. The old one's black and the new one is silver. They both say m9 S-32. Is it possible that they sent me another XT ring by mistake? There's a picture below if I did things right.

    Thanks.

    ChuckD
    I'm not sure of the angle of that picture, but to me it looks like your chain is not sitting right on the ring. There should be no gaps between the chain and the ring, and it should sit evenly on the ring all the way around. If your chain is new then this is either wierd, or it could just be something about the picture.

    For what it's worth, I solved this problem by switing my XTR rings to blackspire super pro rings. I'm also using a shimano chain (with an SRAM powerlink), but I believe the new ring is what solved it. good luck,

    Brad

  41. #41
    less is more
    Reputation: venus1's Avatar
    Join Date
    Aug 2006
    Posts
    823
    The only time I had the skipping thing it was a bad link in the chain. New chain fixed it. I think it is recommended to buy a new chain whenever you change a chain ring? Is this true?
    Finesse is everything.

  42. #42
    mtbr member
    Reputation:
    Join Date
    Feb 2004
    Posts
    594
    That sucks that you are still having the problems. FWIW, the Shimano rep that I spoke to told me very plainly that there is no difference between the XT and LX middle rings except for the color. I too sent an XT ring back for replacement and I am curious to see what they send me.



    Quote Originally Posted by Monument247
    The FedEx person delivered my new middle ring today. I installed it and took my usual desert ride. The short slow climbs worked perfectly where the chain skipped or fell off before. I was happy. At my turnaround point, there's a downhill section then uphill. Nothing steep. I went down and picked up speed and stood and torqued the pedals on the uphill. I deliberately rode over rocks to bounce the rear end and the chain skipped on each pedal stroke. I turned around and went back and tried it again. It happened again. At the end of the ride, I went down a road that has a quick downhill followed by a steep uphill. You try to maintain momentum and clear the hill by staying in a larger gear and standing going up to clear the top. It's bumpy and the chain skipped again. Problem not solved - just different.

    I looked closely at the two rings tonight and, if I didn't know better, I think they sent me another XT ring. The markings are identical except one says EC and the other ED. The old one's black and the new one is silver. They both say m9 S-32. Is it possible that they sent me another XT ring by mistake? There's a picture below if I did things right.

    Thanks.

    ChuckD
    Eat Food. Chop Wood. Ride Bike.

  43. #43
    WIRVNTANASHRSH?
    Reputation: climr's Avatar
    Join Date
    Oct 2005
    Posts
    228
    Quote Originally Posted by venus1
    The only time I had the skipping thing it was a bad link in the chain. New chain fixed it. I think it is recommended to buy a new chain whenever you change a chain ring? Is this true?
    yes. changing the chain often at the first indication of stretch will prolong your drivetrain the most. If your chain/rings/cassette have worn together for a long time, it's recommended to replace them all together.

  44. #44
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    venus1 wrote: "The only time I had the skipping thing it was a bad link in the chain. New chain fixed it. I think it is recommended to buy a new chain whenever you change a chain ring? Is this true?"

    Not when the drivetrain and the whole bike have 500 miles total and it's a known problem with Shimano XT. I hate to think of paying all that money for a great bike and high end components and find out I have to spend money and time to debug Shimano's problems.

    climr - The gaps you see in the chain are really indentations in the chain ring around the teeth. If you look at the black ring, you can see all of these odd shapes. It looks like computer aided design gone wild.

    redclayrambler - I checked specs on the chainstay length on my 29er compared to a 26er Dean Colonel and the difference is 3/4". That would add 2 full links to the chain between the two. I would think that longer stays would make for better shifting anyway because of less acute angles for the chain.

    Before I got the new ring, the skipping occurred while on the cassette third through fifth sprockets from the inside. The new ring fixed that skipping, but now it skips on the sixth sprocket. I can make that happen quite easily.

    I'm to the point where I'm ready to spend money on a different ring and chain, but I hate doing that if I can't be sure that it'll fix the problem. What I probably will do is move the middle ring from my Alivio crank on my Fisher over and see what happens. That ring is steel with less pronounced pins and ramps. If that fixes it, I'll put up with less than smooth shifting until Shimano comes out with a fix that works.

    Thanks.

    ChuckD

  45. #45
    WIRVNTANASHRSH?
    Reputation: climr's Avatar
    Join Date
    Oct 2005
    Posts
    228
    Quote Originally Posted by Monument247
    Not when the drivetrain and the whole bike have 500 miles total and it's a known problem with Shimano XT. I hate to think of paying all that money for a great bike and high end components and find out I have to spend money and time to debug Shimano's problems.
    So your chain is 500 miles old? IMO, 500 miles is alot for a chain. My last cassette (XT) was toast after 800 miles and I generally replace my chains every 250-300. Of course this is very variable, if you don't mash often and your drivetrain doesn't get muddy then your stuff will last longer.

    Sorry if you've already said you're using a new chain, I didn't read every message.

    climr

  46. #46
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    climr - You didn't read every message???? But it's such an interesting thread.

    We must ride in entirely different conditions. My chain length is spot on after 520 miles. No sign of wear. I live in the Arizona desert just 4 miles from the Black Mountains, so I do no riding in wet, muddy conditions. Just sand, big and small rocks, crushed stone, silt and snakes. I ride my mountain bike about 250 to 300 miles a month year round. I get several thousand miles per chain/cassette on my road bike. I certainly don't expect that from a mountain bike in the desert and mountains, but if I had to replace a chain a month, I'd be looking to buy it in bulk. I'll keep a close watch on my chain length.

    Thanks.

    ChuckD

  47. #47
    mtbr member
    Reputation:
    Join Date
    Feb 2004
    Posts
    594
    Quote Originally Posted by Monument247
    I'm to the point where I'm ready to spend money on a different ring and chain, but I hate doing that if I can't be sure that it'll fix the problem. What I probably will do is move the middle ring from my Alivio crank on my Fisher over and see what happens. That ring is steel with less pronounced pins and ramps. If that fixes it, I'll put up with less than smooth shifting until Shimano comes out with a fix that works.
    Monument247, I recommend you try a new Shimano CN-7701 chain on that new LX ring you just installed before you move anything else around. Also, pay very close attention to the toe-in/toe-out of the front derailleur and make sure it is perfectly parallel to the chain rings. Lastly, make sure the height is set to "one penny's thickness" above the chain ring teeth at its closest point. I have not had a single skip/pop/grind since making the three changes (posted above) that included a Shimano CN-7701 chain and I am still using the XT middle ring.

    Good luck!
    Eat Food. Chop Wood. Ride Bike.

  48. #48
    Bike Pimp
    Reputation: D@WS's Avatar
    Join Date
    Sep 2005
    Posts
    242
    There should be no call to change your chain every 250 miles.... that would be every two weeks for some folks.

    My set up:
    Maverick ML7/5
    XT crankset circa December 2005
    SRAM 990 chain
    Shimano R770 front der
    SRAM XO long cage rear der.
    No skipping issues...

    This seems to be a recent phonomenon. And not terribly common as i have sold quite a few XT equipped bikes in the last few months and have heard this issue from only three customers.

    Shimano told me that it was an issue with the ramps as well. When they said they were sending LX c-rings, I imagined that they had older ones as XT and LX are virtually the same middle rings.

    Monument 247: How frustrating! That's a great bike, I want you to enjoy it. I will call Shimano again tomorrow and see what they have to say.
    Wrenchscience.com
    ...Your local bike shop....

  49. #49
    WIRVNTANASHRSH?
    Reputation: climr's Avatar
    Join Date
    Oct 2005
    Posts
    228
    Quote Originally Posted by D@WS
    There should be no call to change your chain every 250 miles.... that would be every two weeks for some folks.
    .
    unless your chain shows stretching of 1/32-1/16" after then.... Ok 250 may be a little of an exaggeration, but I know that my last cassette lasted 800-900 miles and I had been through 3 chains that had stretched and needed replacement. I guess it depends on where and how you ride. Around here you're either climbing or descending and it's often muddy. Dryer, flatter trails and I imagine you'd get a lot more life.

    Point is, measure your chain for stretch and replace it early.

  50. #50
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    Dave in Driggs wrote: "Monument247, I recommend you try a new Shimano CN-7701 chain on that new LX ring you just installed before you move anything else around. Also, pay very close attention to the toe-in/toe-out of the front derailleur and make sure it is perfectly parallel to the chain rings. Lastly, make sure the height is set to "one penny's thickness" above the chain ring teeth at its closest point."

    Okay, I'm taking your advice. I ordered the chain and I may see it by the end of the week. In the meantime, I set up the derailluer as you recommended. It was about 3.5 mm above the big chainring. It's now where you say it should be. When I put the penny in the space, Abe gets a headache. See the attached picture.

    I took the bike for a ride after the adjustments and.....it made no difference. I'll see what the chain does. I have a new Sram chain around for my road bike and I may mount it while I wait for the Shimano to see if it makes any difference. Thanks

    ChuckD
    Attached Images Attached Images

  51. #51
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    climr wrote: "For what it's worth, I solved this problem by switing my XTR rings to blackspire super pro rings. I'm also using a shimano chain (with an SRAM powerlink), but I believe the new ring is what solved it. good luck."

    Did you notice that the Blackspire had bigger (deeper) teeth than the XTR?

    ChuckD
    Last edited by Monument247; 08-22-2006 at 10:38 AM.

  52. #52
    Bike Pimp
    Reputation: D@WS's Avatar
    Join Date
    Sep 2005
    Posts
    242
    Quote Originally Posted by climr

    Point is, measure your chain for stretch and replace it early.
    Agreed!
    Wrenchscience.com
    ...Your local bike shop....

  53. #53
    mtbr member
    Reputation: optimator's Avatar
    Join Date
    Nov 2005
    Posts
    34
    FWIW, I had the exact same problem as Twitches, and Dave in Driggs

    For the record, the following componets in the drive train were replaced:

    XT Middle Ring
    XT Big Ring
    SRAM PC-99 Chain
    M760 Rear Deraileur
    M760 Cassette 11-34
    Deraileur Hanger
    New rear shifter cable and housing

    The bike is a Ventana X-5.

    The problem was the chain would slip off the front ring when under heavy load.

    Everyone had an idea and I looked into every solution. Nothing worked. After talking with Twitches I replaced the front middle ring with a Truvativ chain ring.

    So far...

    Also, as another data point for anyone trying to figure this out, the LBS said they had seen this issue with 3 bikes over the last couple of weeks. The solution was to replace the XT chainring with Race Face.

  54. #54
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413

    Update

    As posted previously, I also had the infamous chain skippage problem. I switched from a SRAM to a Shimano chain and tightened the b-tension a few mm. These two steps solved 90% of the problem. My LX middle chainring replacement came in from Shimano, and I finally got around to taking my XT ring off and trying out the LX ring instead. Problem completely solved.

    P.S. The silver LX middle chainring doesn't look as bad as I thought it would between the two black XT rings.

  55. #55
    mtbr member
    Reputation: CSPRINGS's Avatar
    Join Date
    Feb 2004
    Posts
    447

    Hollowtech Ii Is 50mm Chainline Not 47.5...

    Guys,
    See my rant on Hollowtech II + Enduro = BAD...rant. If your frame is designed for 47.5mm chainline ( as nearly all are) perhaps you should exchange the 760 for the 750/751, ie dump the HTII (50mm chainline) and go back to Hollowtech I which is 47.5mm chainline designed front der.

    http://forums.mtbr.com/showthread.ph...22#post2170722

    Good luck
    CS

  56. #56
    MTB B'dos
    Reputation: LyNx's Avatar
    Join Date
    Oct 2004
    Posts
    21,279
    You must be a gorrila or something to have a cassette only last 800 miles and chains lasting around 250-300 miles - SERIOUSLY!! I weigh around 190lbs w/ gear and I get about 800-1,000 miles from a chain and prob 3 chains to a cassette and I ride in all kinds of conditions from dry dusty to wet clayey mud (that really destroys drive-trains) and I still get the above stated usage out of stuff. I run LX/105 cassettes and until my most recent chain HG73 chains (now running a CN7701)

    Quote Originally Posted by climr
    unless your chain shows stretching of 1/32-1/16" after then.... Ok 250 may be a little of an exaggeration, but I know that my last cassette lasted 800-900 miles and I had been through 3 chains that had stretched and needed replacement. I guess it depends on where and how you ride. Around here you're either climbing or descending and it's often muddy. Dryer, flatter trails and I imagine you'd get a lot more life.

    Point is, measure your chain for stretch and replace it early.
    One day your life will flash before your eyes, will it be worth watching??

  57. #57
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by CSPRINGS
    Guys,
    See my rant on Hollowtech II + Enduro = BAD...rant. If your frame is designed for 47.5mm chainline ( as nearly all are) perhaps you should exchange the 760 for the 750/751, ie dump the HTII (50mm chainline) and go back to Hollowtech I which is 47.5mm chainline designed front der.

    http://forums.mtbr.com/showthread.ph...22#post2170722

    Good luck
    CS
    From reading your thread, it does sound like there are some inherent problems with the HTII design, all in the name of developing a one size fits all approach. Despite FD specs claiming that they're compatible with chainlines from 47.5 to 50 or 51 mm, I've noticed that shifting between rings just isn't as clean when the chainline is extended out that far. Shifting in the rear hasn't been an issue because my effective chainline is fine.

    When I wear out my current set of chainrings, I'll probably switch out the whole HT2 crankset/bb. Until then I'll live with it or possibly switch a spacer over from the drive side to the non-drive side.

  58. #58
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87

    New chain, same old problem..

    My Shimano 7701 chain arrived today. Warning: Order from Performance with $.99 shipping and expect to wait. I ordered it on Sunday evening and it arrived on the second Thursday. I put the chain on today and went for a ride. Same skipping. Standing going up a hill over some rocks that bounce the rear end and the new chain skipped just like the old one. Thanks for your input Dave in Driggs, but it didn't work for me. Time to try another different chain ring,

    ChuckD

  59. #59
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Monument, you may have been sent a new LX chainring with the same problematic shift ramp design, rather than the old LX middle ring. This would explain the same numbers stamped on the rings and why switching to the LX fixed the problem for everyone but you. I can only imagine how frustrated you are right now.

    Now that I seem to have fixed the problem for myself, I've ordered the Shimano XTR FC-960 crankset on clearance, but with Blackspire rings and Phil Wood bearings and seals. I can't wait to get it all in and on my bike. It should be a stiff, durable, and light setup.

  60. #60
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    TLud - I think you're right about the LX ring. I'm hoping to get an older XT, LX or a Truvativ. I'm not frustrated. As long as it's eventually fixed, no big deal. Now, if I put ANOTHER chain ring on and it doesn't fix it, I'll start to get frustrated. Getting the extra four bolts out from the small ring to change the middle is irritating.

    It sounds like you're making some nice changes. I can't see doing anything like that since my bike was built for me in June and I chose XT.

    ChuckD

  61. #61
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    2
    What should be the spacing between rings?
    I've just replaced my middle and granny rings from my Bontrager Race crankset to Middleburn rings and the gap between the large->middle ring looks much more (~ 8mm) whereas the middle->granny looks much less (~5mm?). This is causing my chain to skid past the granny onto the BB. Should the gaps between rings be equal?
    Do i need a spacer?

  62. #62
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by Monument247
    TLud - I think you're right about the LX ring. I'm hoping to get an older XT, LX or a Truvativ. I'm not frustrated. As long as it's eventually fixed, no big deal. Now, if I put ANOTHER chain ring on and it doesn't fix it, I'll start to get frustrated. Getting the extra four bolts out from the small ring to change the middle is irritating.

    It sounds like you're making some nice changes. I can't see doing anything like that since my bike was built for me in June and I chose XT.

    ChuckD
    Yeah, after reading your earlier post, I compared my XT ring to the LX replacement ring, and they had different numbers stamped on them. Agreed that the bolt system on these things blows. I don't remember if you've already done this or not, but when you're changing your middle ring again, definitely switch your spacer over to the non-drive side. I did that this past weekend, and it made a noticeable difference.

    Speaking of which, I had a race this weekend at a pretty gnarly course. During the pre-ride, I managed to break my chain and a couple of teeth on my small ring (didn't realize I had broken the teeth until much later). Having accidentally left my replacement chain at home, I had to repair it, but when I got started again, my chain was skipping in both the small and middle rings. The repaired links didn't feel stiff or stuck, and I didn't yet realize that I had broken teeth on the small ring, so I was starting to freak out that my drivetrain issues were back.

    I figured it all out when I took everything apart. Unfortunately, I also neglected to bring a replacement small ring, so the grinding and skipping climbs during the race were a lot of fun.

    I didn't get my Flux built up until the end of June/beginning of July, so it was hard to justify the new cranks and bottom bracket, but the price was right and I'm moving my XT cranks over to my girlfriend's ride. With the Phil Wood bb bearings and Blackspire rings, I'm excited to finally have a solid drivetrain on an otherwise unbelievable bike.

  63. #63
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by Frase
    What should be the spacing between rings?
    I've just replaced my middle and granny rings from my Bontrager Race crankset to Middleburn rings and the gap between the large->middle ring looks much more (~ 8mm) whereas the middle->granny looks much less (~5mm?). This is causing my chain to skid past the granny onto the BB. Should the gaps between rings be equal?
    Do i need a spacer?
    Not sure how you'd get a spacer between your rings. All you should have to do is adjust (tighten) the low limit screw on your front derailleur.

  64. #64
    mtbr member
    Reputation:
    Join Date
    Mar 2005
    Posts
    1,088
    I'm joining the ranks of chain skipping on the middle ring. I just found this thread and figured I'd add mine to the list. Definately not a 29er only issue.

    2004 Bighit
    New Hone Cranks (Same as LX) (22/32/E13 Bash)
    New SRAM chain
    New XT cassette
    X9 Shifters and Med Cage Rear Derailleur)
    LX E-Type Derailleur so the chain can't really fall all the way off the top.

    This also means I can't pull the spacer and move it to the other side because it's part of the derailleur. Also, it doesn't like shifting to the small ring unless I'm in the large side of the cassette. Not sure if Truvativ ring will really solve everything.

    Coming off the middle ring and landing on my nuts on the stem (Not cool at all )

    Also, I put a new middle ring on some old XT cranks on my Ellsworth ID and it's been skipping off easy too. Not while pushing a hard gear but often when I stop I look down and the chain isn't on the rings anymore. Only happens in the middle ring. I pulled out a link and it's a little better but now I must be very carefull not to shift to the big big gearing.

  65. #65
    A_A
    A_A is offline
    mtbr member
    Reputation: A_A's Avatar
    Join Date
    Sep 2005
    Posts
    177

    same problem here..

    I too am suffering from the middle chainring hop-off problem. My original solution was to put my swanky XTR cranks on my singlespeed with an aftermarket middle ring (Middleburn), see here for details...

    Drivetrain help

    Recently I decided that my bike needed to go on a diet so I figured I'd be a weight weenie and give the XTR cranks another shot. This included buying a new big ring (because I chopped up the original one to make a bash guard. Duhh.) I also bought a shiny new XTR ft derailleur. Guess what happpened? Yep my XTR cranks w/ the Middleburn replacement middle ring still skips under load. The Middleburn has some "short" teeth to apparently help w/ shifting; there are no ramps to speak of. In the 3 months I had my old race face cranks on my bike (rigid 29er) I never had a single problem.

    I think that this generation of stamped 4 arm cranks may actually be flexing under load. Perhaps a new Blackspire ring will hold the chain for a while but I'm thinking it wonít be long before those start to skip too. For years I rode old crappy worn out rings and seldom had this kind of issue. Anyone else think this is a posibility?

  66. #66
    mtbr member
    Reputation:
    Join Date
    Sep 2006
    Posts
    1
    Guys,

    I have been reading this thread with interest as I had the exact same problem with skipping on middle ring regardless of what gear I was in on the back. I did find that it appeared worse in the easier gears of the rear cassette. This mostly occurred under load when starting to climb and especially after starting a climb from a desent.

    My setup is:
    XT cranks, cassette, chain and front and reat derailluer.

    The bike is only about 5 months old and I had the problem from scratch. It was driving me absolutely mad. Nothing worse than having a fantastic bike and not being able to fix a small but frustrating problem.

    After reading the above advice I put a near new base Deore (not LX) ring on that I had taken off my other bike. It has completely fixed the problem. I did shorten the chain which helped a bit before trying the new ring but that was mostly because of a change in RD which left the chain slightly too long anyway.

    For the very minor weight penalty it was worth doing. Not only did it fix the problem but the Deore ring is more solid and looks like it will cope with the torque much better and last longer.

    Anyway, hope this helps someone.

    Cheers.

  67. #67
    Nice no rass
    Reputation: Too Rass Goat's Avatar
    Join Date
    Sep 2005
    Posts
    682
    Interesting thread guys. Out of 4 bikes here we have 4 similar problems. When in the middle ring and hitting rough sections or landing a small jump of some kind, all 4 of our bikes will drop the chain from middle to smallest ring. All 4 have done this since day one. One is a Jamis Dakar stock Truvativ, one is a Kona Dawg D stock race face, Kona Kikapu D stock Truvativ, Kona King Kik stock Race Face. It's driving us nuts, derailleurs are positioned correctly, chains correct length, but if we flex the suspension, they drop to the granny ring. Very annoying. I myself put a SRAM chain on and shortened as far as possible, no change. We are 4 frustrated riders that have tweaked and tweaked our derailluers to no end, they are aligned perfectly. Four different drivetrains with the exact same problem and not a Shimano ring amongst us. Any ideas?

  68. #68
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by Too Rass Goat
    Interesting thread guys. Out of 4 bikes here we have 4 similar problems. When in the middle ring and hitting rough sections or landing a small jump of some kind, all 4 of our bikes will drop the chain from middle to smallest ring. All 4 have done this since day one. One is a Jamis Dakar stock Truvativ, one is a Kona Dawg D stock race face, Kona Kikapu D stock Truvativ, Kona King Kik stock Race Face. It's driving us nuts, derailleurs are positioned correctly, chains correct length, but if we flex the suspension, they drop to the granny ring. Very annoying. I myself put a SRAM chain on and shortened as far as possible, no change. We are 4 frustrated riders that have tweaked and tweaked our derailluers to no end, they are aligned perfectly. Four different drivetrains with the exact same problem and not a Shimano ring amongst us. Any ideas?
    You said that you've tweaked your derailleurs, but have you tried tightening the spring tension and adjusting the b-tension (narrow the gap between the cassette and sprocket to 3 mm or so)? If you've already tried this, I've got nothin'.

  69. #69
    Nice no rass
    Reputation: Too Rass Goat's Avatar
    Join Date
    Sep 2005
    Posts
    682
    Tlud,

    We've been concentrating on the FD as the problem. I will check the B tension of the RD and see if it fixes the problem, thanks.

  70. #70
    Nice no rass
    Reputation: Too Rass Goat's Avatar
    Join Date
    Sep 2005
    Posts
    682
    Cyber beer to you Tlud, you nailed it. I did a very slight adjustment to the B tension and didn't drop the chain once in my ride today. Thanks for catching that.

  71. #71
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Quote Originally Posted by Too Rass Goat
    Cyber beer to you Tlud, you nailed it. I did a very slight adjustment to the B tension and didn't drop the chain once in my ride today. Thanks for catching that.
    Glad to help. Just passin' on what I learned the hard way.

  72. #72
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    My Truvativ ring arrived today. I installed it (boy that little ring is difficult to get back on) and went for a ride. Every place I went where I could cause skipping before, there was none no matter how hard I tried. I consider the problem fixed. Thanks to all contributors and to Dennis at WrenchScience.com. My new bike is now perfect.

    ChuckD

  73. #73
    mtbr member
    Reputation: Evil Patrick's Avatar
    Join Date
    Sep 2004
    Posts
    2,745

    Yep. It's like a disease!

    Myself and 2 other strong riders are having this very same issue. Skipping under torque
    while aggressively climbing rocky/bouncy ups.

    I'm on a Quasi. One of the others is on a Sinister (hardtail) AND a 6.6. I can't remember
    what the other rider rides, but it's a completely different frame. That probably throws a
    sizeable wrench into the chain-line-off diagnosis.

    WTF!?! This was never before an issue. I tried new everything. Casette, middle ring,
    chain, deraileur. CRAP! For me, it's been going on for 3 months now.

    SRAM chain. Still skips.
    XTR chain. Still skips.
    XT middle ring. Still skips.
    FSA middle ring. Still skips.
    The rear cassette is XT and new as well.

    The other riders have also been swapping parts left and right to no avail.

    I HATE having to modify my riding style to accomodate.

    -- Evil Patrick

    Some of my Music

    My Videos

    The trail...shall set you free.

  74. #74
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Evil P, what cranks/BB are you using? Also, if X-type (outboard) BB, what is your spacer setup?
    Last edited by TLud; 09-18-2006 at 02:40 PM.

  75. #75
    mtbr member
    Reputation: Evil Patrick's Avatar
    Join Date
    Sep 2004
    Posts
    2,745
    Quote Originally Posted by TLud
    Evil P, what cranks/BB are you using? Also, if X-type (outboard) BB, what is your spacer setup?
    They're XT with the outboard (X-type) bearings. I believe there is a single, thin spacer, but
    I'm sorry to say that I can't remember if it's on the drive or non-drive side. Whenever I've
    done any maintenance, I've just paid attention to how it disassembles and reassemble
    accordingly.

    I've had these cranks since soon after they were introduced (2003? 2004?). They were not
    "misbehaving" until recently.



    I have trouble believing that the chain line could be the culprit. Mine hasn't changed, yet there
    were good times and now it's bad times. In addition, how can a slight difference - or even
    gross, as in 'up to 5 mm' - in the chain line (as determined by the front offset spacing) really
    make such a difference. Consider what happens to the chain line when the chain is on
    the largest cassette gear vs the smallest cassette gear. There's a, what, 40 mm difference
    (total guess - not looking at a bike now) in the chain line as dictated by that rear position,
    yet we have no skipping issues created by this chain line deviation, do we?



    Has anyone yet touched on a conspiracy theory? More problems = more sales as the
    suckers try to sort it out. All we have to do is machine these puppies so the teeth are a
    little bit too far apart for the chain links!
    Last edited by Evil Patrick; 09-19-2006 at 05:58 AM.
    -- Evil Patrick

    Some of my Music

    My Videos

    The trail...shall set you free.

  76. #76
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    I don't think that wider angle chainline on the new external BB is THE culprit, but I believe it plays a part in combination with other factors. You raise the issue of why it isn't a problem on the larger cogs in the back or the largest chainring in the front, where the chainline is angled even more severely. I think the answer is that despite the more severe chainline angle in those situations, there is also less slack in the chain in those gear combinations to allow for skipping and slippage. In the smallest chainring and cogs, the chain is at its slackest, but the chainline is improved. I can't think of any other reason why people would be having these problems in the middle chainring and middle cogs, which should be the best possible gear combo.

    This theory is supported by the fact that adjusting the b-tension on the rear derailleur really seems to help, but not solve the problem. Also, several people have fixed this problem merely by (1) reverting back to a 47.5 mm chainline by switching spacers over, (2) adjusting the b-tension, and (3) switching chains. Unfortunately, I went back to a 47.5 mm chainline at the same time I switched out my middle ring, so I can't confirm which step solved the problem for me.

    What is strange about your case, Evil Patrick, is that this problem just cropped up out of the blue. Do you recall making any adjustments or switching out any parts right before you started experiencing chain skippage?

    Here would be my suggestions:

    (1) Adjust the b-tension to narrow the gap between the big cog and sprocket wheel as much as possible.

    (2) Put on an unbroken, relatively new Shimano chain.

    (3) If you have a 73 mm BB shell, switch the BB spacer over from the drive side to the non-drive side. If you have a 68 mm BB shell, switch one of the two spacers from the drive side to the non-drive side (you want to end up with two on the non-drive side and one on the drive side). While you're at it, check to see what kind of shape your BB bearings are in. Obviously, this has nothing to do with your problem, but while you're at it, you might as well take a look. When I was screwing with all of this, I noticed how dirty my bearings had gotten and how badly they had worn in only two months.

    (4) Use the FSA middle ring you mentioned in your first post. Shimano has basically admitted that there is a problem with the shift ramp/pin design on these rings. Not to state the obvious, but check to see what kind of shape your rings are in. If they're pretty worn out, you might want to replace them.

    I would honestly be a little surprised if these steps don't solve your skipping problems.

  77. #77
    mtbr member
    Reputation: Evil Patrick's Avatar
    Join Date
    Sep 2004
    Posts
    2,745
    Quote Originally Posted by TLud
    [snip] I think the answer is that despite the more severe chainline angle in those situations, there is also less slack in the chain in those gear combinations to allow for skipping and slippage. In the smallest chainring and cogs, the chain is at its slackest, but the chainline is improved.
    Agreed.


    Quote Originally Posted by TLud
    I can't think of any other reason why people would be having these problems in the middle chainring and middle cogs, which should be the best possible gear combo.
    Yeah. THIS is a mystery. See, I'm in the middle ring and on 3 or 4 in the rear. This _should_
    be a great chain line - almost straight - a little bit off, but almost straight. Yet this is
    still a skipping combo. How about this theory -- I'm just getting too strong?

    Quote Originally Posted by TLud
    This theory is supported by the fact that adjusting the b-tension on the rear derailleur really seems to help, but not solve the problem.
    I already made the same observation -- b-tension "helped", but did not solve the problem.


    Quote Originally Posted by TLud
    Also, several people have fixed this problem merely by (1) reverting back to a 47.5 mm chainline by switching spacers over, (2) adjusting the b-tension, and (3) switching chains. Unfortunately, I went back to a 47.5 mm chainline at the same time I switched out my middle ring, so I can't confirm which step solved the problem for me.
    Well, dag nabbit! The only thing left for me to try is moving the spacer. I hope the crank
    arm doesn't contact the chain stays.


    Quote Originally Posted by TLud
    What is strange about your case, Evil Patrick, is that this problem just cropped up out of the blue. Do you recall making any adjustments or switching out any parts right before you started experiencing chain skippage?
    Well, kinda. In normal maintenance mode, I replaced the chain and very soon after, the
    rear cassette, but not the middle ring. And that worked fine for a while, but then the
    skipping started. Now, that in of itself was a problem that I was already familiar with; see,
    as you know, middle rings all eventually wear out and skipping is the first symptom of
    a ring reaching EOL.

    So, at that point I replaced the middle ring with a brand new FSA. The chain and the
    cassette had maybe a month on them; far too young to be considered a factor. Yet even
    with this new ring, the skipping persisted.

    Now, one might point to the FSA as being the problem here, but looking at it, it looks
    great. No "sharks tooth" wear.


    Quote Originally Posted by TLud

    Here would be my suggestions:

    (1) Adjust the b-tension to narrow the gap between the big cog and sprocket wheel as much as possible.
    Already did that.

    Quote Originally Posted by TLud
    (2) Put on an unbroken, relatively new Shimano chain.
    Already did that. Went from SRAM to XTR.

    Quote Originally Posted by TLud
    (3) If you have a 73 mm BB shell, switch the BB spacer over from the drive side to the non-drive side. If you have a 68 mm BB shell, switch one of the two spacers from the drive side to the non-drive side (you want to end up with two on the non-drive side and one on the drive side).
    Will try. TONITE!


    Quote Originally Posted by TLud
    While you're at it, check to see what kind of shape your BB bearings are in. Obviously, this has nothing to do with your problem, but while you're at it, you might as well take a look. When I was screwing with all of this, I noticed how dirty my bearings had gotten and how badly they had worn in only two months.
    Thanks. I just cleaned and regreased these maybe 3 weeks ago.


    Quote Originally Posted by TLud
    (4) Use the FSA middle ring you mentioned in your first post.
    It's still on. I never bought a shitmano chain ring.

    Quote Originally Posted by TLud
    Shimano has basically admitted that there is a problem with the shift ramp/pin design on these rings.
    I've heard this, but there's something wrong about that admission. What on earth do the
    ramps/pins really have to do with this skipping problem? Nothing! We aren't experiencing
    the problem during shifting. Those ramps and pins have nothing to do with a chain staying
    firmly engaged to the teeth its already riding upon. They're on the side of the chain ring!


    Quote Originally Posted by TLud
    Not to state the obvious, but check to see what kind of shape your rings are in. If they're pretty worn out, you might want to replace them.
    As stated above, that FSA still looks great (which may be a testament to FSA quality?).


    Quote Originally Posted by TLud
    I would honestly be a little surprised if these steps don't solve your skipping problems.
    I'll move the spacer and keep you posted.

    Thanks for the suggestions.
    Last edited by Evil Patrick; 09-19-2006 at 10:59 AM.
    -- Evil Patrick

    Some of my Music

    My Videos

    The trail...shall set you free.

  78. #78
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    I've been following this thread from the beginning (since I started it.) I'm not going to reread the whole thing, but this is my impression of what's going on out there. At some point Shimano changed the shift ramps on their XT and XTR middle rings. Something about that change causes skipping and the chain falling off when the bike rear end is bouncing and the chain is under high tension. FSA followed Shimano's lead and revamped their ramps (Does FSA have a licensing agreement with Shimano?). Truvativ didn't and neither did Blackspire. New FSA rings don't fix the problem - new Truvativ and Blackspire rings do fix it. I'm sure that Shimano has a good idea of what's going on but they're staying quiet. That's how I see it.

    ChuckD
    Last edited by Monument247; 09-19-2006 at 03:27 PM.

  79. #79
    mtbr member
    Reputation: Evil Patrick's Avatar
    Join Date
    Sep 2004
    Posts
    2,745
    Quote Originally Posted by Monument247
    I've been following this thread from the beginning (since I started it.) I'm not going to reread the whole thing, but this is my impression of what's going on out there. At some point Shimano changed the shift ramps on their XT and XTR middle rings. Something about that change causes skipping and the chain falling off when the bike rear end is bouncing and the chain is under high tension. FSA followed Shimano's lead and revamped their ramps (Does FSA have a licensing agreement with Shimano?). Truvativ didn't and neither did Blackspire. New FSA rings don't fix the problem - new Truvativ and Blackspire rings do fix it. I'm sure that Shimano has a good idea of what's going on but their staying quiet. That's how I see it.

    ChuckD

    I'll shamelessly cut and paste from my previous post:

    I've heard this, but there's something wrong about that admission. What on earth do the
    ramps/pins really have to do with this skipping problem? Nothing! We aren't experiencing
    the problem during shifting. Those ramps and pins have nothing to do with a chain staying
    firmly engaged to the teeth its already riding upon. They're on the side of the chain ring!
    -- Evil Patrick

    Some of my Music

    My Videos

    The trail...shall set you free.

  80. #80
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    413
    Although my first instinct is always to blame the engine, I was able to quickly rule out my leg strength as a possible cause of this skippage problem.

    I think it's a safe bet that the new Shimano shift ramp/pin design is involved to some extent. The external bottom brackets with their 50 mm chainline have been out for years, and although they've been blamed for a variety of shifting and drivetrain issues, this skippage problem is very recent and happens to coincide with the release of the new ring design.

    My guess is that the shift ramp/pin design issue, the 50 mm chainline, and not enough chain tension all works in conjunction to cause this skipping/slipping problem. I haven't really looked closely at the XT middle chainring that I was having problems with to visualize how this might happen, but I suspect that the combination of extreme torque and bouncing rearend causes the chain to push off the front of the chainring, but only in gear combinations that (1) allow enough slack in the chain, AND (2) create enough of an angle in the chainline to cause lateral friction between the chain and ring (i.e., the middle ring and cogs).

    Evil Patrick, to address your point, it doesn't necessarily have to be the actual ramps and pins that are causing the problem. Possibly, in redisigning the ramps and pins, Shimano altered the basic structure of the ring enough to cause problems. Who knows, but if Shimano is readily admitting that there is likely an issue with the design to consumers who call in complaining of this problem, I think it's safe to assume that there is some sort of issue with the design.

    If what Monument said about FSA is correct and FSA is using essentially the same revamped design, this might explain a lot of your confusion. It is entirely possible that your first middle ring was skipping because it was worn out and that your FSA replacement ring is skipping because it shares the same faulty design as the new Shimano rings. If taking the steps I listed above doesn't eliminate the problem, you may want to take the final step of trying out a Truvativ ring. Frustrating, I know, but better than having to unnecessarily downshift to the granny ring on the steeps.

    Or you could just do what I ultimately did: buy the '06 XTR cranks on closeout, switch out the stock rings for Blackspire rings and the bearings with Phil Wood or Enduro bearings, and you'll have the smoothest drivetrain you've ever ridden. Of course, I only did all of this AFTER I went to all the trouble of fixing this skipping problem on my XT cranks/BB.

  81. #81
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    Evil Patrick wrote: "....What on earth do the ramps/pins really have to do with this skipping problem?...."

    Please see the chainring picture below and the picture I posted on page 1 of the thread and you'll see an elaborate structure that extends right up into the tooth profile. You'll also see on page 1 that the chain on the ring is touching a shift pin. A lot of jiggling and slapping around and who knows what could happen.

    ChuckD
    Attached Images Attached Images

  82. #82
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    12
    How ironic - today is the day I get my new Turner 5 Spot and I now find this thread. I had bought a Jamis XLT 3.0 a few months back and fell in love with it - except for the one fact that every once in a while I'd crack my nuts on the top tube because of the chain skipping under heavy load.

    I worked with my dealer and with Jamis - we tried everything (all the adjustments we could think of including a new rear triangle and new frame). Three months later Jamis gave me credit on the frame and I swapped the components onto a Turner 5 Spot which should be at my door any minute now. Come on Fed Ex guy!

    I read through the entire thread and there is some good stuff. I am amazed that Jamis was not aware of the situation along with potential solutions that were presented in this thread. I will call them shortly.

    With the Jamis I could reproduce the chain slipping (minus the nut cracking) at will under certain conditions. I also ride a Stumpjumper FSR 5" with XT rings and that one has not caused me any issues. Actually I had the chain jump off once. But once in 200 miles is not a bad ratio - we could live with that. Now I get my Turner and we'll see what happens.

    I will let you guys know what I run into. I think the problem is dependant a lot on bike specifics. For instance the Stumpjumper has a XTR RD while the Jamis and the new Turner have a SRAM X0. My understanding is the B tension is much higher on the XTR. Also I know that the Specialized frame is stiffer than the Jamis and that the rear suspension pivots in a more "up and down" fashion where the Jamis pivots with more of an arc. All these little bike specifics will result in specific fixes. Sometimes all that is needed is to change out the middle ring or maybe tighten down the B tension. So I think the solutions are in this thread - you just need to find the specific solutions needed for your specific setup.

    I never had these issues on my $1,200 bike. Damn.

  83. #83
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    12
    Update on my new ride - Turner 5 Spot. So far no problems with chain skipping. I had no issues with the climbs where I normally have problems.

    Specialized Stumpjumper FSR
    - XT Chain Rings / XTR RD (No problems)
    - Very Stiff Frame side to side
    - Hardly any chain slap even when suspension is active

    Turner 5 Spot
    - XT Chain Rings / SRAM XO RD (No problems so far)
    - Alot of flex side to side
    - Hardly any chain slap even when suspension is active

    Jamis XLT 3.0
    - XT Chain Rings / SRAM XO RD (Always a problem)
    - Relatively stiff frame side to side. Not as stiff as the FSR but not nearly as flexable as the Turner.
    - Alot of chain slap when suspension is active.

    The chain slap is a noticable differance between the three bikes. I wonder for the people who have not found a solution yet if they are experiencing a lot of chain slap and if that is where they need to look for their solution. The B tension should help with this no?

  84. #84
    Bike Pimp
    Reputation: D@WS's Avatar
    Join Date
    Sep 2005
    Posts
    242
    Quote Originally Posted by Monument247
    My Truvativ ring arrived today. I installed it (boy that little ring is difficult to get back on) and went for a ride. Every place I went where I could cause skipping before, there was none no matter how hard I tried. I consider the problem fixed. Thanks to all contributors and to Dennis at WrenchScience.com. My new bike is now perfect.

    ChuckD
    SWEET!

    That's a load off... I'm glad that the Truvativ ring sorted the problem. Finally you can enjoy your new bike as you should. Have fun Chuck.
    Wrenchscience.com
    ...Your local bike shop....

  85. #85
    Go Bruins!
    Reputation: ooctrl's Avatar
    Join Date
    Aug 2006
    Posts
    585
    I also had a problem with my chain falling off the middle ring up front when I was in a larger cog in the rear. The problem came down to a bent middle chain ring. I was able to use a hard rubber mallet to bang it back into place. I checked the gaps all the way around to make sure they were the same and everything was cool. I also increased the chain tension on RD a few turns. I figure it couldnt' hurt.

  86. #86
    mtbr member
    Reputation:
    Join Date
    Sep 2006
    Posts
    1
    Does anyone think resting fingers on dual shifter/brake levers can cause this mystery slipping?

  87. #87
    Live 2 Ride
    Reputation: Kona0197's Avatar
    Join Date
    Oct 2004
    Posts
    5,952
    I do. hence the reason I stick to SRAM shifters.
    My Bike: '15 Trek FX 7.2
    My Blog: http://http://kona0197.wordpress.com/

  88. #88
    CrazyEye
    Guest

    Straight 9 Speed?

    I have the same problem of slipping from the middle to little. I've been thinking about just running one gear up front and removing the front shifter and derailer. Does anyone do this?

  89. #89
    mtbr member
    Reputation: wickedracin's Avatar
    Join Date
    Jun 2006
    Posts
    237
    Quote Originally Posted by Monument247
    I have a problem with chain skipping on my Dean Colonel 29er. Itís got about 250 miles on it. The drive train is Sram X0 in back and Shimano XT in front with X0 shifters. When Iím really torquing the cranks while Iím on the center chain ring and on about the third to fifth sprocket (from the inside) in back and I hit some rough trail that bounces the rear end, the chain skips. The skip seems to be at the front, not the back. Worse than that, at least three times when Iíve been pushing up a short hill in those gears, the chain has come off and fallen on the bottom bracket inside of the smallest chain ring. The front derailleur will still be positioned on the middle ring.

    Thinking that the front derailleur might be out of adjustment, Iíve increased cable tension so that the chain will barely drop from the large to middle, but that didnít help. The chain length seems spot on. Large to large has the rear derailleur stretched so that the chain is almost going straight through the pulleys.

    Any suggestions?

    Thanks.

    ChuckD
    are you running a dual ring system if so I might have a solution for you. go to www.wickedracin.com and look under Dualrailleur I am in the process of patenting a guide developed to be attached to a front XT 760 derailleur. It guides the chain to the selected sprocket, plus the guide moves with the derailleur, so you have the benefits of a single ring chain guide, but are able to utilize either 2 or 3 sprocket setup. There is no way the chain can fail off using a bash ring and out inner plate. This may help the jumping problem but it sounds like you may need to replace your middle ringÖ.. I am currently working on a 3 ring system that is a little lighter and doesnít use a bash guard. You should also check that your chain is not to long.
    Attached Images Attached Images

  90. #90
    pedaller
    Reputation: Noelg's Avatar
    Join Date
    Jan 2004
    Posts
    2,400

    Add another to the list...

    I just found this thread while trying to figure out what the heck is wrong with my bike and the freaking chain slippage...

    After many frustrating rides, 2 ruined cassettes, 3 broken chains and lots of slippage...I'm at the end of my rope.

    I spent 2+ hrs at my LBS yesterday (The 3rd visit re: same problem) and left without my bike. They replaced the chain, chain rings, cassette, removed the cranks & bottom bracket, adjusted the derailer and still no luck. They seemd to think that the chain is not staying in contact with enough teeth on the chain ring and that is causing the problem. They recommended a shorter cage derailer but didn't have one in stock so the bike is still there.

    After reading this thread, I called the LBS and mentioned the 4-page thread on MTBR re: the chain rings and they said that the problem has been corrected by Shimano and that the "new" chain ring is the improved version. I'm not so sure - especially considering that I can still reproduce the problem on a smooth inclined surface under load.

    I don't know what to do at this point....
    "Nobody ever told me not to try" - Curious George Soundtrack by Jack Johnson

  91. #91
    mtbr member
    Reputation: wickedracin's Avatar
    Join Date
    Jun 2006
    Posts
    237

    when is your chain falling off

    When is your chain skipping/falling off.... What type of bike do you have? Are you running dual rings... are you shortening your chain to the right size. You shouldnít have to go to a shorter derailleur on the rear there shouldnít be so many issue with your sprocket. It would be the first time the LBS didnít know what they are doing.

  92. #92
    pedaller
    Reputation: Noelg's Avatar
    Join Date
    Jan 2004
    Posts
    2,400
    When is your chain skipping/falling off....
    Anytime I put a big load on it. On the trail this is when I get out of the saddle on a climb. (But I was also able to do it in granny gear and the middle cog with a little load - not spining) At the shop it was when I tried to pedal and apply the brakes. Then to remove the variable of possible shifting while braking-with the dual shifters, I just rode up the inclined loading dock next door to the LBS with my hands on the grips only. As with others here, it seems to happen in the middle cogs and bigger (lower gears). The LBS guy watched me everytime and determined that the chain is slipping up front and with a new chain and cassette and chain rings....was puzzled.

    What type of bike do you have? Are you running dual rings...
    I have a 2006 Kona Explosif - steel HT. The shop also moved the back wheel all the back to "help narrow the angle of the chain coming off the front chain rings to no avail.

    are you shortening your chain to the right size.
    The LBS replaced the chain. I watched them and they seemed to do it correctly.

    You shouldn’t have to go to a shorter derailleur on the rear there shouldn’t be so many issue with your sprocket. It would be the first time the LBS didn’t know what they are doing.
    In reading other threads here, I have the same impression. I'm not even sure a shorter cage makes sense with an 11-34 cog and the standard mtn triple ring (44-32-22).

    This thread alone makes me wonder if the real problem is the XT middle ring to begin with...
    "Nobody ever told me not to try" - Curious George Soundtrack by Jack Johnson

  93. #93
    mtbr member
    Reputation:
    Join Date
    Mar 2006
    Posts
    87
    As soon as I got a Truvativ middle ring to replace the Shimano, the problem went away. Have your LBS try something else on the middle.

    ChuckD

  94. #94
    mtbr member
    Reputation: CoffeeBean's Avatar
    Join Date
    Mar 2007
    Posts
    146

    Skipping Middle Chainring!!!

    6thElement referred me to this:

    I just bought my 2007 Specialized Stumpjumper Pro Carbon 2 days ago and this is not the beginning of a great appreciation for the machine.

    I am currently in a ton of pain as I actually did spin out in the worst possible way. I not only smashed up my knee really bad, I also pulled out of my pedal in order to avoid falling backwards down the steep edge I was climbing and ripped up the backside of my leg. It was a pretty bloody ride home I must say. I kept swearing something was not right about the middle chainring and could not figure out the problem, but here are others with the same issue.



    What should I do? How do I convince my dealer to fix this issue? Should this turn into legal action against Shimano and/or Specialized? Why isn't there a recall on this issue?

    I worked really hard to afford something this nice and now I get my leg banged up from a defective part? No other solution other than to simply ignore this and buy some steel replacement rings?

    Truly bummed....

    I also worry as NoelG that my LBS won't help since I am certain Shimano is going to say I already have the fixed chainring on my bike....

  95. #95
    pedaller
    Reputation: Noelg's Avatar
    Join Date
    Jan 2004
    Posts
    2,400

    Update

    Well Shimano insisted that the solution was to put on an all-Shimano drivertrain (BIG SURPRISE) so they replaced the Sram chain with a Shimano one. I took the bike out for an easy ride and still had the problem.

    I returned to the shop and left the bike again. They "fix" the problem and ask me to come back with my riding shoes to "test" it out. When I get there I find that they've replaced the rear derailleur with another long cage XT derailer and replaced the cable. I ride over to a wash with a guy from the shop and the bike seems to be working fine. It even "feels" better. This is the first time that I'm unable to recreate the problem. I tell them I was going for a good ride the following day and that I'd report back.

    The next day's ride was a dream. I went through all the gears, on rocky climbs and the bike was perfect. After my ride, I drove back to the bike shop with an ice cold 12-pack of the mechanic's favorite beer.

    We'll see how it goes on my next ride....
    "Nobody ever told me not to try" - Curious George Soundtrack by Jack Johnson

  96. #96
    mtbr member
    Reputation: CoffeeBean's Avatar
    Join Date
    Mar 2007
    Posts
    146

    Skipping Middle Chainring!!!

    Wow man! I have one of those on my old bike sitting right next to my new StumpJumper!!!! It is 2 months old. I wonder if I should try this also before juggling chainrings and making a big stink of this at the LBS.

    It's just so frustrating doing all this work on a shiny new machine which has seen more time in the garage since the skipping got out of control...

    Thanks for the information....I will more than likely try this to not lose trailtime tomorrow...

    Cheers!

  97. #97
    I Love my Rize
    Reputation: danoalb's Avatar
    Join Date
    Dec 2005
    Posts
    798

    This is the only answer

    Just put this ring and say goodbye to all your chain skipping problems with your GARBAGE XT CHAIN RINGS. I would also replace your granny with a m580 LX steel ring and then you will have tha crankset of your dreams just itsy bitsy heavier but WELL WORTH THE extra grams for the HUGE step up in performance (durability and wear). Alu rings have no place for a granny or middle ring. THEY ARE TOTAL GARBAGE. You cannot use a regular Deore m510 granny ring on a hollowtech II crank without grinding the inside of it but they make the m580 LX granny ring in steel so problem solved no grinding to do. You can't beat the price also. You will be thanking me once you do this, your welcome.


    22t Steel LX granny ring m580 for hollowtech II cranks... http://store.airbomb.com/ItemDesc.asp?IC=CR5808

    32t Steel Deore ring m510.....http://store.airbomb.com/ItemDesc.asp?IC=CR2998
    Early to bed early to RIZE makes a man healthy, wealthy <(scratch that) and wize.

    RIGHTY on a LEFTY

  98. #98
    mtbr member
    Reputation: CoffeeBean's Avatar
    Join Date
    Mar 2007
    Posts
    146

    Skipping Middle Chainring!!!

    I started to remove my super nice SRAM X.0 rear derailleur and install my XT derailleur when I suddenly decided I simply could not tear pieces off a good bike just to try and solve a problem which I did not think originated in the rear.

    I then figured I would cut to the chase and simply go buy myself a new chainring and slap it on there and be done with this problem.

    I returned back to my LBS and first asked them to check over my bike and verify everything was in perfect operating order. They assured me everything was perfect and the scenario I described to them seemed really far fetched in their opinion. I also agreed with them except for the fact that I knew it could actually happen. They told me to leave the bike with them for a few days to determine if there was more they could find wrong. I politely disagreed and stated that I simply wanted to purchase an LX Deore 32t chainring which I saw sitting up on the shelf. The owner of the shop thought I was nuts, but he gave me the benefit of the doubt. He installed, tuned and gave me the chainring for no charge whatsoever! He held onto the defective chainring to have a word with his Shimano rep upon hearing back from me. Tomorrow I am going to inform him that after 30 miles in the roughest sections of trails I could possibly imagine, I have yet to skip when riding in my middle chainring, or any chainring for that matter!

    Cheers!
    CoffeeBean...

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •