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Thread: Mojo XTR

  1. #1
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    Mojo XTR

    Any one with 970 XTR crank set: how many spacers have you installed on the drive and non-drive side? According to the Shimano instructions - there should be 2 on the drive and 1 on the non-drive for the 68” BB. Is this what you have? Trying to figure out why I get the chain suck from time to time
    Thanks in advance.

  2. #2
    It's the axle
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    I've got 960's. Two on drive side, one on non drive side.

    Chainsuck from middle to granny? I can get it if I shift while pedaling. You have to lift off the pedaling or you'll get chainsuck. At least that's my experience. I'm listening, if there are other opinions on this.

  3. #3
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    thanks for the info

    Quote Originally Posted by Gregg K
    I've got 960's. Two on drive side, one on non drive side.

    Chainsuck from middle to granny? I can get it if I shift while pedaling. You have to lift off the pedaling or you'll get chainsuck. At least that's my experience. I'm listening, if there are other opinions on this.
    i've dropped from the middle to the granny cog while pedaling and got the chain sucked in.
    my bike just got put toghether, so this may be attributed to some gunk on the chain and other factors. First thing that came to my mind - the spacers on the crank. Now that i know i've got it right, i can move on to other usual suspects. I will post what i've found.

    Do you stop pedaling all together to drop from the middle to the granny? That's not good.

    Thanks again for the reply

  4. #4
    It's the axle
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    I'm still trying to figure it out. It may be that brand new equipment has a tenancy to hang onto the chain, versus broken in equipment. It's my belief that by keeping pedal power to the cranks while downshifting, the last links are still getting interference between the chain and chainring. And therefore the chain doesn't release. The only way I can avoid chainsuck is to essentially coast through the gear change. I really doubt it's chainline. That's a very small change in chain angle. I have to say I was surprised when it happened the other day. Everything was brand new. By backing off, it hasn't happened since. I would bet that once a bit worn, shifting can occur even with power to the cranks. I see no other explanation under the circumstances. Note to self- continue working on hydraulic bike. Chains suck, as efficient as they are.

  5. #5
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    i am not entirely sure that this chain suck can be attributed to the newishness of the parts. I am using the transplant crankset that's been transffered from my other bike and has about 500 miles on it.
    I wonder if other people are having the same problem?
    I will hate to have to coast though downshifting. I am in Colorado, so i need my gears willing and able at any time...

  6. #6
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    yucky sucky chain suck-y

    In 100s of miles, I've had three (too many) chain sucks. All recently.

    I run FSA, not XTR.

    Twice I attributed it to over zealous use of my gripshifts (once dropping a whole bunch of gears at one time - and - once dropping a gear on the front and rear almost simultaneously ). The last time was a simple middle to small ring drop while on an incline with the rear on the 34t cog.

  7. #7
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    Quote Originally Posted by jchembel
    Any one with 970 XTR crank set: how many spacers have you installed on the drive and non-drive side? According to the Shimano instructions - there should be 2 on the drive and 1 on the non-drive for the 68” BB. Is this what you have? Trying to figure out why I get the chain suck from time to time
    Thanks in advance.
    That's how I set mine up. I've had a bit of chain suck but it isn't common, just once in a while.
    A bicycle will take you to fantastic places....if you let it.


    Ibis fan since '08 now rolling on the big wheeled Ripley.

  8. #8
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    Quote Originally Posted by jchembel
    i am not entirely sure that this chain suck can be attributed to the newishness of the parts. I am using the transplant crankset that's been transffered from my other bike and has about 500 miles on it.
    I wonder if other people are having the same problem?
    500 miles on the rings would be enough wear to suck with a new chain if you ride strong or climb very much.

    If chain suck is just a rare occurrence, the rings may break in to the tighter new chain in a few rides. Just back off the power more than usual when shifting until it's good again.

    Rings wear faster now than with 7 and 8 speed.

    For me I have to replace at least the granny and middle when the rear cogs need replacing to work with a new chain. I have to replace the big ring also every two rear cog sets.

  9. #9
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    I am going to give it some time and observe

    Quote Originally Posted by derby
    500 miles on the rings would be enough wear to suck with a new chain if you ride strong or climb very much.

    If chain suck is just a rare occurrence, the rings may break in to the tighter new chain in a few rides. Just back off the power more than usual when shifting until it's good again.

    Rings wear faster now than with 7 and 8 speed.

    For me I have to replace at least the granny and middle when the rear cogs need replacing to work with a new chain. I have to replace the big ring also every two rear cog sets.

    BTW, I’ve found the bike to be pretty darn sweet. Not a bad climber for a 5.5” at all What I am most impressed by – the handling. Precise and neutral at the same time.
    I am coming off the 2005 Racer X 100, that is supposedly a benchmark of good handling.
    I got to admit, I am liking the Mojo’s handling quite a bit more.
    Thanks everyone for your response.

  10. #10
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    I initially installed 2 washers on the drive side per the instructions. Occasionally the chain would jump down to the granny gear from the middle chain ring on its own. I moved one washer from the drive side to the non drive side and the problem went away. One washer on the drive side has to stay there otherwise the big chainring gets really close to the swingarm.

    Kenny

  11. #11
    Keep Riding !!
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    I've also experienced the dreaded chainsuck on my Mojo with drive train transfered from previous bike.
    Replaced chain, cassette & chainrings, it was needed anyway, which improved matters however still get chainsuck when shifting from middle to granny ring under load.
    The only way I can get around this is to change down early under light load (back off a little) which means you just have to look ahead more and anticipate changing down, I don't this is a bad thing anyways.

    Still a great ride and very pleased, I tell people its like riding a very efficient couch
    Just Ride !

  12. #12
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    chain suck

    I have also experienced chain suck on my mojo, after having never experienced if before. I have been instructed by LBS to not shift to granny gear under any load. This will take some planning, but it's better than twisting a chain link. I am anxious to see if someone has a different work around resolution.

    I am running full XTR components.

    Other than chain suck, I love my Mojo. Just got back from a week in Moab. What a blast - can it get any better than a carbon bike on miles of slickrock trail and 70 degree weather????

  13. #13
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    Here's a link to good knowledge on the basic chain suck causes:
    http://www.fagan.co.za/Bikes/Csuck/

    I also have had more downshift middle to granny chain-suck on the Mojo than any bike before. It's probably happened 3 times in the last 8 months I've had the Mojo. Not bad but I almost never had downshifting to granny related chain-suck problems before.

    I think it might be caused because the chainline is not centered middle to middle sprockets anymore using the external bearing bottom brackets. And the tooth gap dimension between teeth crossing down the rings hasn't been shortened or lengthened slightly, to compensate for the angle change to the new chainline. However, changing that dimension might screw up the up shifting.

    Is it time for a wider rear hub standard (which would also reduce spoke dish)?
    Last edited by derby; 04-07-2007 at 09:27 AM.

  14. #14
    It's the axle
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    There is one other thought on why this could be happening. New chain, new components.

    Chain length. Ordinarily I go with a tight chain on the largest combination of gears. On the medium frame, Ibis recommends 112 links.

    I'm getting at chain tension. Chainsuck, in the cases we're talking about here, is most likely due to lack of tension. I don't know what the chainline is on the xtr setup. But I doubt it is as significant a factor as tension. The reason being, given enough tension, chainsuck would never happen.

    I suggest fewer links, or increasing rear derailleur tension adjustment.

    This has nothing to do with Ibis or the Mojo. It's simply geometry of the gear arrangement.

    I'm going to drop to 110 links and see if that eliminates the problem.

  15. #15
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    please, let us know if shortening the chain turned out to be a solution....

    Quote Originally Posted by Gregg K
    There is one other thought on why this could be happening. New chain, new components.

    Chain length. Ordinarily I go with a tight chain on the largest combination of gears. On the medium frame, Ibis recommends 112 links.

    I'm getting at chain tension. Chainsuck, in the cases we're talking about here, is most likely due to lack of tension. I don't know what the chainline is on the xtr setup. But I doubt it is as significant a factor as tension. The reason being, given enough tension, chainsuck would never happen.

    I suggest fewer links, or increasing rear derailleur tension adjustment.

    This has nothing to do with Ibis or the Mojo. It's simply geometry of the gear arrangement.

    I'm going to drop to 110 links and see if that eliminates the problem.
    please, let us know if shortening the chain turned out to be a solution....

  16. #16
    It's the axle
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    Well for starters, I've removed two links. And 110 links looks just like the chain on my other bike when it's in the large combo. And I've had chainsuck two times in four years on that bike.



    Less weight.
    Less chainslap.
    Maybe less chainsuck.

    More wear from extra tension, but I can live with whatever minimal amount that might be.

  17. #17
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    Quote Originally Posted by Gregg K
    There is one other thought on why this could be happening. New chain, new components.

    Chain length. Ordinarily I go with a tight chain on the largest combination of gears. On the medium frame, Ibis recommends 112 links.

    I'm getting at chain tension. Chainsuck, in the cases we're talking about here, is most likely due to lack of tension. I don't know what the chainline is on the xtr setup. But I doubt it is as significant a factor as tension. The reason being, given enough tension, chainsuck would never happen.

    I suggest fewer links, or increasing rear derailleur tension adjustment.

    This has nothing to do with Ibis or the Mojo. It's simply geometry of the gear arrangement.

    I'm going to drop to 110 links and see if that eliminates the problem.
    Careful!!! Never ride with a tight chain in the largest gears on any full suspension.

    Shimano recommends no tighter than tight on the big gears PLUS two links. That would be the absolute minimum safe chain length for the Mojo.

    The big-big gear combination should be avoided for longer duration use due to an increased rate of wear to the teeth of both gears from cross chain alignment.

    But if you accidentally shift into that combo with a tight chain you will either break the chain or tweak the swingarms and possibly break the frame, or the least damage would be very rapid wear of the pivots, chain, and gears.

    The rearward axle path during travel effectively lengthens the chain stay measurement.

  18. #18
    It's the axle
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    Derby, you're absolutely right.

    I did check it. 110 is totally at the limit. With suspension bottomed out, and in the big combination of gears, the chain is almost taut.

    I'm going to run it this way. I never ever go into the large large gears. And even the second largest cog on the rear, I'm comfortable with it.

    Having said that, any larger chainwheel, and it's crunch.

    There's a good reason for the 112 links.

    But I"m also fairly certain this is why we are seeing a bit more chainsuck.

    Thanks again!

  19. #19
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    Rock N Roll chain lube blue reduces chain suck compared to other stuff.

  20. #20
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    Quote Originally Posted by Gregg K
    Derby, you're absolutely right.

    I did check it. 110 is totally at the limit. With suspension bottomed out, and in the big combination of gears, the chain is almost taut.

    I'm going to run it this way. I never ever go into the large large gears. And even the second largest cog on the rear, I'm comfortable with it.

    Having said that, any larger chainwheel, and it's crunch.

    There's a good reason for the 112 links.

    But I"m also fairly certain this is why we are seeing a bit more chainsuck.

    Thanks again!
    Good you checked at bottom travel.

    Pulling out two links will only move the rear derailleur forward the distance of 1 link. It's not a significant difference in spring tension. I say better be safe with chain length.

    A medium size rear derailleur cage should give better chain tension too, but in the granny the chain clearance rubbing under the stay might become a problem in all by the largest few rear cogs.

    Longer travel can have more shifting problems. Just plan to ease off a little power when downshifting and there isn't a real problem on the Mojo, as long as the chain and gears are aged together.

  21. #21
    It's the axle
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    Actually pulling two links moves the derailleur cage two links. Not one link. The cage is the only thing moving. The chain distance from the top of the sprockets remains the same. It's the idler that moves to take up the two links.


    Edited to delete a bunch of blabbing. And now it's time to go outside and ride with the crew.
    Last edited by Gregg K; 04-08-2007 at 10:27 AM.

  22. #22
    flow where ever you go
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    solved my chain suck

    Quote Originally Posted by noshortcuts
    In 100s of miles, I've had three (too many) chain sucks. All recently.

    I run FSA, not XTR.

    Twice I attributed it to over zealous use of my gripshifts (once dropping a whole bunch of gears at one time - and - once dropping a gear on the front and rear almost simultaneously ). The last time was a simple middle to small ring drop while on an incline with the rear on the 34t cog.
    After a couple more chain sucks that could not be attributed to sloppy shifts, I finally noticed that the small ring in the front had all rounded teeth. I replaced the small ring and have had no more chain suck.

    "I must not be crazy because I'm seriously questioning my sanity"

  23. #23
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    Hey guys,
    I have had chain suck issues with my wife's bike. It's an 04 epic. I installed one of these http://www.ajsbikeparts.com/ It's a frame guard that prevents chain suck alltogether. I now have them installed on both my wifes bike and my 06 carbon epic. I am not sure if this will fit the mojo. On the website it tells you how to measure for fit. I am building a mojo (just waiting for the fork to arrive). As soon as I get it built up I will let you know if it works. Basically it replaces one of the spacers on the drive side crank. There is also a product called Ronnie Ring (search on google) that actually bolts to the small chainring which might work also. All I know is chain suck sucks major, it totally thrashes the frame and looks like #@$% real quick.

  24. #24
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    This is a killer

    I'm interested in a Mojo but this is a feature that Ibis needs to sort out pdq.

    I had a lovely custom titanium 29er a year or two back and it was a thing of beauty. But it had completetly intractable chainsuck. I replaced everything, tried different spacers and adopted the gear changing techniques listed above. I still got it most rides and the last straw was when I had to walk/coast 10kms home as it was so totally stuck. Anyway, that bike is now a happy singlespeed.

    But I needed a geared bike, and it needed to be well -worked out and properly developed - so I got a 2005 Turner. I swapped all the drive chain kit straight over. Guess what - not a single single bit of chainsuck since.

    I've had it a couple of years now and it's great, but the Mojo may be better, so I'm interested. But not with any vestiges of chainsuck attached to its reputation - the memories are too painful.

  25. #25
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    Does anyone have chain-suck issues on big-to-middle rings on the Mojo?

    I don't use the granny ring whilst clmbing steep hills on my Kona Coiler, so can't see me needing it on the Mojo (when it comes next week). Any comments appreciated...

    I'm a noob so don't shoot me down!

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