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  1. #1
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    New Mojo owner with drivetrain question

    Hi,
    Had my mind set to buy a Titus Motolite 2 but went to another bike shop to take a look at a Felt MTB that was highly recommended. Thought about a Santa Cruz but wasn't convinced about the single pivot system. I had been out of mountain biking for 10 years, I still own a 96 Klein Mantra Pro with its unitized rear triangle if you are old enough to remember that. My friend owns several Iron Horse bikes and swears by the DW Link system. Anyway, I was awestruck when I saw the custom built up Mojo with no shimano components. I just couldn't get it out of my mind. Not being an implulsive buyer, I bought it the following week. My friend bought another one that same day and we walked out with 2 Mojos.

    The bike was great, what a difference from the Klein which I still like but not as much as the Mojo. I've got a problem with the Mojos drivetrain. The Crankset is a Truvative Stylo Team, the bottom bracket is an external bearing Truvative (but not the Howitzer model), pedals are Crank Bros Candy SL, Top of the line SRAM chain and cassette, SRAM XO triggers and rear der, next gen front der. The problem occurs when the driverain is placed under load such as climbing. It is a grinding sensation throughout the rotation felt through the pedals and bottom bracket that is annoying. When I am spinning it is not so noticable but still present. The grinding is felt through both pedals but mostly through the left pedal. Kinda feels like no grease in the bearings. The pedals a brand spanking new, the bottom bracket isabout a month old. I took it to the shop where I bought the bike and they said that one of the pivot bolts was loose and they tightened it up. That's it ! They're only explaination for the problem. Needless to saylel, that did not solve the problem and I doubt I'll recommend that shop after spending 5G.

    Along with my Klein, I ride my Litespeed Ultimate so I have shelved the Mojo until I can figure what the problem is with your appreciated help and any workable components. Since I'm from the Monterey Peninsula, I was happy to learn that Ibis is a local company nearby in Scotts Valley. Thanks in advance for your input.

  2. #2
    flow where ever you go
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    Sounds to me like the bottom bracket needs to be taken out and inspected for grease, alignment, and proper installation.

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

  3. #3
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    Try your dealer again. A loose pivot bearing bolt could allow the suspension to mis-align under load and throw the chainline off center further. Repairs are sometimes a mysterious and tedious process of elimination. Make sure your mechanic can feel the problem.

    When my '06 Mojo was brand new with FSA cranks with external BB, Sram cogs, and Wiperman chain, it had some grinding feel under load especially with cross chained gear combinations until the drivetrain broke in after about 10 rides. Perhaps it was the sharp new gear teeth and more offset chainline due to the external BB. But I blame it mostly on the Wiperman chain, it is the crappyest chain I've ever used, rusting visibly overnight after every washoff and wore out quicker than my Sram chains using the same lube.

    I don't know if this is your problem. Since it happens in every gear under load it's probably either a chain than still is loosening up (sideways) or BB.

  4. #4
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    I'd check the BB as well.

    I was running a Truvativ Stylo (Carbon) crankset on my Mojo until one of the external BB's seized up after a few weeks.

    I've since switched to an M970 XTR and have no complaints. Smooth as silk.

  5. #5
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    Thanks and comment

    Thanks for the replies from "hans", "noshortcuts", "derby" and "carbonken".

    I thought it could be the bottom braket. The mechanic took it out for a spin with the brake on to simulate load and said he felt it too. He just tightened a pivot bolt and gave it back to me and said it's fixed. Which it wasn't. Disappointing service from an Ibis dealer. Anyway I will look into all of your suggestions.

    I was wondering if anyone has heard anything good or bad about the FSA, Truvativ, XT and XTR bottom brackets that have been reworked by a company with larger ceramic bearings, lube, rings and dust seals? That way you could still use your crank. I'm thinking of that as an option.

  6. #6
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    You can get Enduro bearings to replace your current ones, I wouldn't spend the cash for ceramics. I'd still go back to the shop, if the bottom bracket is bad it should be a warranty issue. Since your buddy has a Mojo you could try swapping bottom brackets and see if it fixes it. If you have the tool it's a five minute job.

  7. #7
    Wzl
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    chainline issue

    I am having a similar issue. I have two rides on a new mojo. I am running an XT crank with outboard bearings using a 22-36 chainring combo. I was noticing some drive train noise that sounded a lot like a very dirty dried out chain when I was up in the 30 and 34 tooth cogs and in the 36 tooth chainring. The sound goes away when I am in the 22 tooth chainring on down lower on the cassette. I took a good look at the chainline and I can see that it's crossed up pretty good between the 36 tooth ring and the 34 tooth cog. Then I noticed that there are two spacers on the drive side of the crank. So the question is do I need both those spacers or can I take on out to effectively movemy chainline inward by about a mm? I believe this will cure the problem but how do I know if the 22 tooth cog is too close to the frame? Looks like it will still clear the nearest pivot bolt.

    What's the word the the Ibis folks? 1 spacer or two?

  8. #8
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    Quote Originally Posted by Wzl
    I am having a similar issue. I have two rides on a new mojo. I am running an XT crank with outboard bearings using a 22-36 chainring combo. I was noticing some drive train noise that sounded a lot like a very dirty dried out chain when I was up in the 30 and 34 tooth cogs and in the 36 tooth chainring. The sound goes away when I am in the 22 tooth chainring on down lower on the cassette. I took a good look at the chainline and I can see that it's crossed up pretty good between the 36 tooth ring and the 34 tooth cog. Then I noticed that there are two spacers on the drive side of the crank. So the question is do I need both those spacers or can I take on out to effectively movemy chainline inward by about a mm? I believe this will cure the problem but how do I know if the 22 tooth cog is too close to the frame? Looks like it will still clear the nearest pivot bolt.

    What's the word the the Ibis folks? 1 spacer or two?
    Have a read about chainline on this website - http://www.sheldonbrown.com/chainline.html

    Basically you shouldn't be using the largest rear cogs with the largest front chainrings. The idea is to keep the chain as straight as possible. Generally this means use the 3 largest rear with the smallest chain ring, the 3 middle rear one cogs with the middle chainring, and the 3 smallest rear with the largest chainring. Of course with is only a guide, but you'll put a lot of strain on the chain & wear out the chainrings & cassette very quickly if you go to the extreme.

    Do a search on mojo chainline, as the issue has been discussed previously, and it discusses the spaces for XT cranks too - Mojo chainline.

  9. #9
    Wzl
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    I agree that running a big ring over to the biggest cogs would be bad but I am talking about a middle ring here. I do it on all of my other bikes without this issue.

    I will check the link you provided. Thanks.

  10. #10
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    Oh yeah, my mistake I saw 22-36 & thought for some reason you meant 22-44 (I hadn't had my coffee yet).
    Anyway, I wouldn't be using the middle chainring with a 34 on the rear. You may still have a bad chain line. Actually I've got an XT 11-32 cassette & never use the 2 largest anyway. Still, I did find my chain line from the middle ring to the 3rd largest on rear wasn't that great.

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