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  1. #1
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    What's wrong with my Mojo?

    The frame flexes as with any Mojo. However, it has developed a knock at the end of each flex. It's especially noticable when I'm hammering up a steep climb--when I pedal (left-right), at the max force of each pedal stroke, it flexes and knocks at the peak of the flex.

    I was initially suspecting that the bottom bracket bearings were shot or that the crank arm was coming loose. However, when I push on the rear triangle, I can replicate the flex, which is accompanied by a slight knock/clunk.

    Anyone experience this or what do you think is wrong?

  2. #2
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    Crankarm hitting the swingarm under flex? That could give you a knocking sound but probably would leave a mark that you could see.

  3. #3
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    "at the end of each flex" you mean each time the suspension transitions from compress to extend and back?

    If so: check all your pivots starting with the shock for something that could be loose, missing bushing, etc.
    All your base are belong to ME.

  4. #4
    aka dan51
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    Quote Originally Posted by MinskyBA
    If so: check all your pivots starting with the shock for something that could be loose, missing bushing, etc.
    Do this. ^^^
    I had a similar problem a while back, and one of the bolts in the lower link had worked loose a little bit. I snugged it up and things were back to awesome.
    Those who know, ride a Mojo AND a Mojo HD.
    Quadzilla
    Quote Originally Posted by benja55
    Ok, whatever, cold water on my bike boner right there.

  5. #5
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    Quote Originally Posted by dan51
    Do this. ^^^
    I had a similar problem a while back, and one of the bolts in the lower link had worked loose a little bit. I snugged it up and things were back to awesome.
    Same here, lower link was a little lose causing the knocking/clunking sound. I tightened it up and all was fine.

    Per Hans: "Feel free to tighten it [lower link] pretty tight. We didn't feel the need to specify on those fasteners since they are quite strong and will handle a pretty high torque with no ill effects.
    If you want to break out the torque wrench, 10 ft lbs on the front one and a little less, maybe 8, on the rear should be good. That's 120 inch lbs front, 96 rear, if you have one that reads in inches.
    Hans"

  6. #6
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    Larsey, it feels exactly as if that is what's happening and I initially thought that was the case. It's not making any contact, though.

    Minsky, what I meant by "at the end of each flex" is when the rear triangle flexes (or moves) from left to right, horizontally.

    Dan & Rider, what did you guys notice when the lower pivot bolt came loose? Ironically, the lower pivot bolt is the only one loose, but maybe a 1/4 turns worth at most. You think that will do it? The drive side crank arm was in the way, so I didn't get to hold that side to tighten it.

  7. #7
    MPI
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    Take a look at front triangles lower links mounting axle if it has come loose from carbon fibre. You have to disassemble the lower link from the frame. I had a similar problem while ago. Otherwise it is links mounting bolts or shocks ones.

    Greets MPI!
    http://www.kiva.org - Loans That Change Lives

  8. #8
    aka dan51
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    Quote Originally Posted by alexb650
    Dan & Rider, what did you guys notice when the lower pivot bolt came loose? Ironically, the lower pivot bolt is the only one loose, but maybe a 1/4 turns worth at most. You think that will do it? The drive side crank arm was in the way, so I didn't get to hold that side to tighten it.
    Take the crank off so you can access both sides.
    Mine wasn't very loose, but it made enough of a difference to start clunking.
    Check to see if the lower link is cracked. There was a thread on here about that happening a few weeks ago.
    Those who know, ride a Mojo AND a Mojo HD.
    Quadzilla
    Quote Originally Posted by benja55
    Ok, whatever, cold water on my bike boner right there.

  9. #9
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    Quote Originally Posted by dan51
    Take the crank off so you can access both sides.
    Mine wasn't very loose, but it made enough of a difference to start clunking.
    Check to see if the lower link is cracked. There was a thread on here about that happening a few weeks ago.
    tightening the lower link bolt only helped slightly but the problem is still there. No cracks in the link. What do you think is next in the elimination process?

  10. #10
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    Quote Originally Posted by MPI
    Take a look at front triangles lower links mounting axle if it has come loose from carbon fibre. You have to disassemble the lower link from the frame. I had a similar problem while ago. Otherwise it is links mounting bolts or shocks ones.

    Greets MPI!
    thanks for your input MPI. How do I determine what 'loose' is? Meaning, I can't move it by hand or anything. What would I do if the mounting axle is loose?

  11. #11
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    Mojo SL

    Iím on my third front triangle; the first one had sever flex that made the pedals contact the rear chain stay. The second one developed the same as the first and also had a creaking noise while pedaling. There was also a white powdery substance on the inside portion of the top tube that would build up over time. The powdery substance would accumulate in a straight line and could be rubbed off.

    I took the bike to my LBS and Ibis sent in a replacement front triangle, They never said what that powdery substance was, but I think maybe it was where two areas failed to bond. I still love my Mojo and so far so good with this last frame, it been two years or so. So look for an unusual white substance under the top tube area.

  12. #12
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    Quote Originally Posted by alexb650
    tightening the lower link bolt only helped slightly but the problem is still there. No cracks in the link. What do you think is next in the elimination process?
    I think you should still remove the crank and make sure the pivot is snug.
    milesW

  13. #13
    MPI
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    Quote Originally Posted by alexb650
    thanks for your input MPI. How do I determine what 'loose' is? Meaning, I can't move it by hand or anything. What would I do if the mounting axle is loose?
    You will see a crack round the axle if it is loose. You can normally also feel it by hand. If it loose it is matter of Ibis great CS. I am sure they will take of the problem. Be sute to check all the other issues mentioned in thread. You might also check that the shock is tightened properly and there is nothing wrong with shock bushings by twisting the shock for examle with glove. Take a good grab with your hands ( do not use any tools, pliers or etc ) and try to gently twist the shock sideways.
    http://www.kiva.org - Loans That Change Lives

  14. #14
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    Hey Boyo

    The issue could be that the main axle bonded into the frame has begun to separate. A known issue on a few early Mojo's.

    When you grasp the back of the bike and flex it left and right, put your other hand on the front triangles main lower pivot. Feel for play. Got something? Cracks off, remove bolt and link. Check the alloy pivot which is meant to be bonded into the frame. It may be the culprit. It may be difficult to move it with your fingers without the added leverage of the rear end, but you might see the gap around the axle and with a tool through the hole, you can exert enough force to see the axle's movement.......

    ....or maybe not.

  15. #15
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    Quote Originally Posted by Big Wave Dave
    Hey Boyo

    The issue could be that the main axle bonded into the frame has begun to separate. A known issue on a few early Mojo's.
    I'll try and check it out later today. How would I tighten the axle back up if that's the problem? I assume the frame is toast if that's the culprit?

  16. #16
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    1st check all hardware to make sure it's tight
    2nd if the above does not solve the problem check:
    rear hub, free hub in particular, quick release as well
    main pivot integrity is a pretty obvious one. the crank arm to chain stay gap changes a lot even to the point to the cranks hitting the stays if the pivot tube is loose. Possibly very worn lower rear bearings...

    Let us know what you find and if you need any help getting it fixed or with further diagnosis.

    The local dealer is usually helpful as well...

    H
    Hans
    Ibis Cycles, Inc.

  17. #17
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    Thank you all for your help. Found and fixed the problem. The axle that the lower pivot bolts go into had detached from the carbon.

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