Tired of getting your chain wedged when it drops?- Mtbr.com
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  1. #1
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    Tired of getting your chain wedged when it drops?

    So, I've had an issue w/ the chain getting wedged between the granny gear and the rear swingarm on my XCE. My wife's burner has the same problem.

    I was looking @ this : http://www.cambriabike.com/chain&gui...rame_guard.htm

    Ironically it's a Turner they're using to demo the install


    Has anybody used this? I'm thinking about buying one just to try it out.

    Dave

  2. #2
    No, that's not phonetic
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    I saw an ad for that thing recently and it looks pretty cool. The problem is that it is pretty thick and so would move the crank outboard a bit and may cause chainline issues.

    Better yet would be to get a Heim 3 chain guide. I just bought one from Ventanarama and the thing is damn cool. It is like the MRP LRP but has an angled roller and thinner arm. It is designed to accept 3 chainrings, and I use a bash guard, so I cut it shorter and shaved the flange on the guide pulley down (I would have taken pics but I had sent my cameras out to the field already). With the arm full-length, you cannot rotate the Heim back and up to be higher than the bash-guard without it coming close to the rear tire, so that is why I cut the arm shorter. It mounts on a thin stainless steel arm so it hardly affects the bb cup spacing. The benefit is that you never drop the chain any more so there is nothing to jam. On really rough descents (like in Moab) my chain would often drop to the granny ring while coasting, but not fall totally off. With the Heim, it would not even bounce off the bigger rings. The roller is slightly tapered to the outside so it feeds the chain a little outboard so that the chain will not drop to the granny while backpedaling either. That AJ's thing would still let the chain fall down to the granny through bounce or backpedaling (but not farther). Seems like a half-measure. The only thing with the Heim is that the chain does make a sound as it rolls over it. A little dampening would be cool. It is very light to boot. They run about $60. Check the Heim out.

    My video techniques can be found in this thread.

  3. #3
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    Quote Originally Posted by tscheezy
    I would have taken pics but I had sent my cameras out to the field already.
    Ah come on tscheezy, just work a little of your Photoshop magic on the pic above. We can't wait two months to see the mod ! Seriously though I think I'll get one of these ordered up and see if I can't figure my way through the modifications. I drop my chain repetitively and have the scars on the seat stay to prove it .

  4. #4
    rio
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    shark fin

    i had the same issue on my 5- spot and fixed it by installing a shimano "shark fin" up side down on the bottom of my chain stay. i inverted the shark fin so the fin is tucked in between the large and middle chain rings; and about 1/8" from the large chainring. this was a chronic problem, that is now solved, at least it solved my problem!


    Quote Originally Posted by CrashTheDOG
    Ah come on tscheezy, just work a little of your Photoshop magic on the pic above. We can't wait two months to see the mod ! Seriously though I think I'll get one of these ordered up and see if I can't figure my way through the modifications. I drop my chain repetitively and have the scars on the seat stay to prove it .

  5. #5
    No, that's not phonetic
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    The roller mounts on the arm in a long, slotted hole. The slot allows you to slide the roller up and down the arm before tightening it in the desired position. Cutting the end off the arm actually allows you to slide the roller out the end of the slot, which is sorta handy. I cut about 1" off. The arm is made out of an "L" shaped length of stainless. I cut an angle off the end of the inside of the L for extra tire clearance (I basically replicated the original shape after cutting the end down). This all allowed me to rotate the arm up and back to just under the chainstay so that the roller sat higher than the bottom of the bash ring. That way the roller would not get slammed if I slide over a rock/log. The arm itself is not very stout metal so it is pretty important to get it up and back out of harm's way. The roller has a pretty high flange on it to wrap around the outside of the chain/chainring. It was tall enough that it rubbed the inside of the crank arm on each rotation when I moved the roller in next to the bash ring, so I shaved the flange down a bit too. A bunch of easy mods, really. I was amazed how tight the bb cup holds the arm in place. It won't move on its own.

    DGC uses a chainstay mounted guide which he just flips the chain up and through for DH sections. You could leave enough space between the Heim roller and the bashring to get the chain out of the roller for flat and uphills, but the soft clicking noise of the chain running over the roller is not that annoying so I just have it set up permanently.

    Heim website

    (not my pic, but it gives you an idea)



    Another thing is that your drive-side bb cup needs to have a flange on it. Some Isis bbs (like the RF XS) will not work. I have a UN-71 XT bb.
    My video techniques can be found in this thread.

  6. #6
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    Hmmm....

    Honestly I don't usually have _that_ many occurences where the chain falls off; I have a bash guard and a short cage rear der so tension is pretty high. Problem is, it seems that on the occasions that it does come off it FREQUENTLY wedges itself in there. I think that's because It's usually a slow really rocky section where my rear suspension is heavily compressed which opens up the gap enough to drop it down in there.

    I couldn't handle anything that caused drag/noise. That would drive me crazy.

    I ordered it along w/ a "Deda Elementi Dog Fang Chain Deflector"

    We'll see how they work.

    Dave

  7. #7
    M070R-M0U7H FR3NCHI3
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    I second the Heim guide. I know John personally and seen him test the crap out of that guide! He tested it for at least 1.5 years before he even released it. If I was in the market for such a guide, I would definitely get the Heim Guide.

  8. #8
    No, that's not phonetic
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    Quote Originally Posted by MightySchmoePong
    I ordered it along w/ a "Deda Elementi Dog Fang Chain Deflector" We'll see how they work.
    The seat tube does not come down low enough to mount that Deda thing anywhere near the chainring unfortunately. The machined bb block is in the way. That's the same reason you have to use a bottom swing f der. The AJ frame guard should help keep the chain on the granny, but I don't think it would do anything against chain suck.

    Aren't accessories fun?
    My video techniques can be found in this thread.

  9. #9
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    Yeah... I think you're right.

    Quote Originally Posted by tscheezy
    The seat tube does not come down low enough to mount that Deda thing anywhere near the chainring unfortunately. The machined bb block is in the way. That's the same reason you have to use a bottom swing f der. The AJ frame guard should help keep the chain on the granny, but I don't think it would do anything against chain suck.

    Aren't accessories fun?


    I was thinking I'd be able to do it on the wife's burner but I don't think that has enough clearance either after looking @ it again. Oh well, 11 bucks down the drain.

  10. #10
    Flyin Canine
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    So guys I see how the Heim guide adds tension and keeps the chain from falling off to the outside but does it actually keep the chain from falling off the inside of the granny and wedging in between the swingarm pivot and the rings?

    Also to Tscheezy, thanks for the tips on the Heim. I have one on my wife's Bullit and the end of the arm is pretty close to her rear tire. What did you use to cut it? I have a dremel tool and some other tools I could use but I was worried about deforming the metal if I don't cut it right.

  11. #11
    Lay off the Levers
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    Quote Originally Posted by shanedawg
    ...I have one on my wife's Bullit and...
    Your wife rides a Bullit? Man, did you marry well!
    Faster is better, even when it's not.

  12. #12
    Flyin Canine
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    Quote Originally Posted by Bikezilla
    Your wife rides a Bullit? Man, did you marry well!
    Yeah I tried to talk her into a Heckler, but she was having none of it. After riding her Juliana at Whistler last year, really finding it's limits and the location of the hospital, she said she wanted to get big travel. She wants to do the small rock drop on dirt merchant this year now that she has the right bike for it. I also tried to convince her that the z150SL would save her some weight and still perform great but she wanted coils and nothing else. Here's a pic. Since I took it I moved the heim a little further up to tuck it away a little better.
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  13. #13
    No, that's not phonetic
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    Quote Originally Posted by shanedawg
    So guys I see how the Heim guide adds tension and keeps the chain from falling off to the outside but does it actually keep the chain from falling off the inside of the granny and wedging in between the swingarm pivot and the rings?
    No, the Heim does not offer a guard all the way around the bb shell like the AJ frame guard thing does. I guess the point is not that it would stop a chain which has already fallen off from ending up in the wrong spot, it's that it would prevent the chain from falling off in the first place. Chains fall off because the rear der arm gets swinging forward as the chain whips up and down, and throws slack forward and the chain unwraps itself from the chainring. The chainguide stops the chain bounce from getting as far as the chainrings, so the chain stays on the ring's teeth. The plate on the Heim which encircles the bb shell behind the bb cup flange is a larger diameter than the bb shell itself, but not big enough to do what the AJ thing does.

    If all you are after is something to stop the chain from jamming against the frame in the infrequent event of the chain falling off, the AJ would be the thing for you. My chain bounces off the middle ring frequently when doing rough descents, but does not end up jamming (just ends up on the granny sorta cockeyed), so the Heim is better for me.

    Quote Originally Posted by shanedawg
    I have one on my wife's Bullit and the end of the arm is pretty close to her rear tire. What did you use to cut it? I have a dremel tool and some other tools I could use but I was worried about deforming the metal if I don't cut it right.
    I just put it in a vice and used a hack-saw. Afterwards I took the rough edges off with a flat file. Nothing fancy. When finished, it had the same overall shape as the original, except it was about 1" shorter. It is now too short to work with a large chainring, but I don't anticipate mounting one again.
    My video techniques can be found in this thread.

  14. #14
    Flyin Canine
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    Quote Originally Posted by shanedawg
    So guys I see how the Heim guide adds tension and keeps the chain from falling off to the outside but does it actually keep the chain from falling off the inside of the granny and wedging in between the swingarm pivot and the rings?
    I was just thinking about this some more and had another question. I have an 01 RFX and it looks like it has a hole for an e-type ft derailluer ( not sure if that's really what it's for ). Since the heim is so thin maybe I could run the heim and an e-type and it would keep the chain from falling off either side of the rings. Granted I would probably have to get a bb that has adjustable chain line. This may not be of any help on the burners or spots though as I don't know if they have the hole. Here's a pic of the hole. Let me know you guys think.
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  15. #15
    No, that's not phonetic
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    Quote Originally Posted by shanedawg
    I have an 01 RFX and it looks like it has a hole for an e-type ft derailluer ( not sure if that's really what it's for ). Since the heim is so thin maybe I could run the heim and an e-type and it would keep the chain from falling off either side of the rings.
    I kinda think you only go for the E-type when it is the only style your bike accepts. They are supposedly kinda flexy and weird. Yes, it would do what you are suggesting, but so would any peice of stiff sheet metal cut to fit. I'd start with a basic chain guide, and if you still have jamming probs, start getting creative then. There really is no such thing as an adjustable chainline bb which has a flange which would allow you to mount stuff between it and the bb shell. Adjustable chainline bbs have no flange so you can end up positioning it where ever you want. The holes in your RFX are for mounting an IS chainguide. Why not just bolt a chunk of sheet metal to those holes as a chain stopper, for instance. May look pretty ghetto, but if you like to fabricate stuff (I do), you may have the "next big thing".
    My video techniques can be found in this thread.

  16. #16
    Flyin Canine
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    Quote Originally Posted by tscheezy
    I kinda think you only go for the E-type when it is the only style your bike accepts. They are supposedly kinda flexy and weird. Yes, it would do what you are suggesting, but so would any peice of stiff sheet metal cut to fit. I'd start with a basic chain guide, and if you still have jamming probs, start getting creative then. There really is no such thing as an adjustable chainline bb which has a flange which would allow you to mount stuff between it and the bb shell. Adjustable chainline bbs have no flange so you can end up positioning it where ever you want. The holes in your RFX are for mounting an IS chainguide. Why not just bolt a chunk of sheet metal to those holes as a chain stopper, for instance. May look pretty ghetto, but if you like to fabricate stuff (I do), you may have the "next big thing".
    Hmm, I have not had an e-type on one of my personal bikes before, only on friends bikes I worked on so I don't know that much about them. I don't really want to buy new cranks but I think the new X-type stuff from RaceFace has adjustable chainline that might work for this purpose.

    Since I already have new cranks, bb, and fd I guess it would be a lot cheaper to wait and see if I would still have the problem after getting a Heim or similar. The only time I have jammed a chain on the inside was on my Titus QM when the fd was slightly out of adjustment and the chain would overshift from the middle to the granny once in a while while climbing. I think if I can keep the fd tuned while running a heim and a semi-short chain I won't have any troubles at all with downhills causing it. Sorry for dragging this thread out so much It's just that I just got this frame and don't wan't to gouge the pivot area like I did on the Titus and apparantly the previous owner of the RFX did. When it arrived the frame looked new except for a major case of chainsuck.

  17. #17
    Lay off the Levers
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    I have three words...

    Quote Originally Posted by shanedawg
    Yeah I tried to talk her into a Heckler, but she was having none of it. After riding her Juliana at Whistler last year,...I also tried to convince her that the z150SL would save her some weight and still perform great but she wanted coils and nothing else.
    You GO girrrrllllll!!!!!!
    Faster is better, even when it's not.

  18. #18
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    Hmm, my RFX bears similar scars...

    ...what has worked best for me is following (assuming you run granny/middle/basher). I'm not sure if you're more concerned about a) the chain falling onto the CS from above when it is dropped to the inside of the granny, or b) the chain being pulled up from below by the granny.
    1. Be sure not to run too much chain. If you kept your chain the same length from when you previously ran 3 rings it is time to drop several links. Keep this within reason though as extreme(ly bad) chain lines lead to accelerated wear which is worsened by high tension created by (too) short chains.
    2. Keep everything reasonably clean/lubed.
    3. Watch for the "shark-finning" of your granny. If it develops significant "bite" it will tend to keep purchase on the pins (more so if grimy) and pull the chain up a bit vs. releasing it cleanly. This is exacerbated by suspension movement and chain growth/tensioning. To the extent I'm running a granny/middle combo I check the granny for deformation every so often. On steel grannys I've found that I can just flip the granny a few times before it's spent and needing of replacement.
    4. I will often run my RFX in 1x8 (32Tx12/32 XTR stainless cluster) mode using an E-13 chain guide. This is tits but may not help you if you ride in areas with steep/extended climbs.
    5. I've not used them, but you can also purchase various ST mounted pieces that line up below the front mech and alongside the granny to prohibit a dropping of the chain to the inside.
    I've worn out my welcome. Hope this helps.

    Sean
    Professional Amateur

  19. #19
    Daniel the Dog
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    One sucky thing about Turners....

    Quote Originally Posted by MightySchmoePong
    So, I've had an issue w/ the chain getting wedged between the granny gear and the rear swingarm on my XCE. My wife's burner has the same problem.

    I was looking @ this : http://www.cambriabike.com/chain&gui...rame_guard.htm

    Ironically it's a Turner they're using to demo the install


    Has anybody used this? I'm thinking about buying one just to try it out.

    Dave
    You can drop the chain down and have a bear of a time getting it unclogged. It sucks. Let me know if you find a good solution. There seems to be some decent solutions below.

    Jaybo

  20. #20
    DGC
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    Quote Originally Posted by Jaybo
    You can drop the chain down and have a bear of a time getting it unclogged. It sucks. Let me know if you find a good solution. There seems to be some decent solutions below.

    Jaybo
    This is the guide that Tscheezy mentioned of mine. I also run a LRP bash plate only, and not the roller guide of LRP. Reasoning?......chainline and shifting.
    I will run both the guide (shown) and the bash plate and still have all 3 rings I run, 22,32,38.
    Just depends on what I am riding that week or 2.
    There are what seems to be some decent solutions, but be aware of what they might do to your chainline and shifting.
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  21. #21
    oly
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    The power of search! HAHA.... Excuse my lazyness.

    So, here are 2 photos of my first single roller guide. I had a truvativ box guide that I just used the roller, and bottom plate from. It was steel though and was real easy to bend. the banshee also had messed up mounting holes so it hung too low. I recreated it a few times for this bike and the next few i had. Looks pretty much like the HEIM except for maybe how the roller works. Im thinking of adapting my design for the 5spot. Ill post pics if i do.
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  22. #22
    oly
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    Quote Originally Posted by oly
    The power of search! HAHA.... Excuse my lazyness.

    So, here are 2 photos of my first single roller guide. I had a truvativ box guide that I just used the roller, and bottom plate from. It was steel though and was real easy to bend. the banshee also had messed up mounting holes so it hung too low. I recreated it a few times for this bike and the next few i had. Looks pretty much like the HEIM except for maybe how the roller works. Im thinking of adapting my design for the 5spot. Ill post pics if i do.
    Photo2, Ive since replaced the truvativ roller with a LRP roller...... never have issues...... and they only cost me the price of the roller.....
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  23. #23
    Flyin Canine
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    I wound up going with the E-13 DRS guide and bash ring setup and it is working great so far. Went to Whistler and did 2 days at the DH park. Then did 2 days cross XC/Freeriding and didn't drop the chain once and had the use of both front chainrings. It is also very quiet and produces almost no noticable drag. I also shortened the chain a couple of links. Here are some pics:
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