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  1. #1
    MC MasterShake
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    ML & chainrub on large tires.

    I finally figured out what that noise was on this bike. My chain is so close to my tire that when I bounce the bike in full granny the chain rubs my tires. I'm running some worn down Kenda Nevegal 2.35's which easily fit the chainstays. I also had to dremel down my front derailleur a bit because it was rubbing as well. Is there any way to push the drivetrain out a few mm's or so on the crankarm?

  2. #2
    MC MasterShake
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    Duh! I could just get wider BB. I'm currently running a 113. What size are you guys riding?

  3. #3
    FM
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    Quote Originally Posted by woodyak
    Duh! I could just get wider BB. I'm currently running a 113. What size are you guys riding?
    The BB spindle width you should use depends on your crankset. The BB shell width is determined by the frame.

    You should be able to run pretty frickin' huge tires before the chain rubs on them- at least true DH 2.5's. Bigger than the motolite can take in any case. So it sounds to me like yoru BB spindle is too short. Post what kind of cranks you are running and I will try to help you figure out the correct spindle length.

  4. #4
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    Strange

    Quote Originally Posted by woodyak
    I finally figured out what that noise was on this bike. My chain is so close to my tire that when I bounce the bike in full granny the chain rubs my tires. I'm running some worn down Kenda Nevegal 2.35's which easily fit the chainstays. I also had to dremel down my front derailleur a bit because it was rubbing as well. Is there any way to push the drivetrain out a few mm's or so on the crankarm?
    I've been running WTB 2.3 Timberwolves in the back all summer, which has real knob to knob width of 2.43 inches, and my chain clears my tire with a lot of room to spare. I'm running a Shimano X-type BB.... I don't know what the spindle length is.

    What kind of BB are you running? The only thing I can think of is maybe you are not running the right combination of BB spacers (if it requires them).

    Regards,

    EndUser
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  5. #5
    MC MasterShake
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    Here are a couple pics showing how close the chain is. The camera is about 5" away in these pics.

    I'm running XT cranks and XT BB. The cranks are FC-M572's and the BB is a BB-ES71 size 73x113. Here's a picture of how close it is. These came off my XS Quasi which came off my XS Loco and now it's on my XS Moto-lite.

    I see they make a 73x118. Would that be long enough? It's only 2mm more on each side.
    Attached Images Attached Images

  6. #6
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    I can't imagine why you couldn't.

    I can't imagine why you couldn't run a 73x118. The two things it would change is the chainline and the Q-factor. Regarding the chainline, pushing out the cranks will cause a little more wear on the drivetrain when using the middle chainring and biggest cogs. The chain will contact those lowest gears at a higher angle causing more friction thus more wear and tear. Most chainlines are optimized around the middle chainring for obvious reasons, but I don't think there will be an issue of decreased performance junt an increase in equipment wear.

    The Q-factor, or the distance between crank arms, will increase which may cause some initial "getting use to" but I don't think that will be a problem. When I started using the new X-type BB system, which has a longer q-factor, my knees hurt for about a month before they got use to it. No big deal.

    Hope this helps.

    Regards,

    EndUser
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  7. #7
    FM
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    I am stumped by this, since I run a 113x73 with shimano octalink XT cranks on my other bike and have no problems. The frame doesn't really mattter if the BB shel width is the same.

    You could go to a 118 width but I would avoid this, as it will compromise your chainline..... it might work fine, but you might be more prone to dropping your chain especially when running middle ring/ big cog.

  8. #8
    MC MasterShake
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    Crap. Figures this kind of stuff always happens to me. Maybe if I take a couple links out of the chain it won't bounce so much. Or I could just live with it...

  9. #9
    the 36 year old grom
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    well. I think my chain might be that close in the grany gear, too. but I make a point about shifting into the middle front ring and out of the rear grany when I'm going down hill and taking big hits.

    in my experiance you'll drop your chain taking big hits in the granny. ie, if it bounces off while you are in the granny it will drop to the frame and you'll have to get off the bike to pull the chain back up. if you are in the middle ring you have more tension on the chain and if it does jump off it will land on the grany ring and next time you pedal the chain will shift back onto the middle ring. I've also been known to run a chain guide.

    And in the rear, the chain can bounce and end up between the spokes and the biggest cog. which can be a PTA to get out. so I do my best never to do nasty stuff in the 34 tooth cog.

  10. #10
    MC MasterShake
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    Ideally, that would work but it's real tough to do on the trails we have here. We don't have long uphills and downhills we have rollercoaster trails with rocks on them. So by the end of the quick technical climb (when you're about to puke) the trail goes straight down, turns real quick and then back up again. You rarely even get a pedal stroke in during these downhills. You might have time to shift twice in that time and you don't want to be caught in you're middle ring when you're at the bottom of the steep climb. And it's not that I'm a slow rider. I'm usually in front.

    I run a 2x9 setup and it's rare that I even use the middle ring unless I'm cruising on the fireroads. I guess I need to look at more narrow tires

    It's pretty strange because I never had this problem with my Quasi or my Loco.

  11. #11
    FM
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    Quote Originally Posted by woodyak
    Maybe if I take a couple links out of the chain it won't bounce so much. .
    Absolutely. This is the main advantage of running a 2x9 set up is you can runa shorter chain which means less bouncing around. are you running 2x9 or 3x9? Eitehr way, shorten the chain there is just enough to allow the biggest chainring and biggest cog combination. maybe 1 extra link for SRAM stuff.

    I don't think I have any mroe rear tire clearance then you do, based on your picture looking down at the chainrings...

  12. #12
    MC MasterShake
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    Yup. 2x9. I'll try shortening the chain. I wonder if the Loco and Quasi had longer chainstays thereby stretching the chain more??? Maybe that's why I never had this problem with those frames.

  13. #13
    the 36 year old grom
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    Quote Originally Posted by woodyak
    Ideally, that would work but it's real tough to do on the trails we have here. We don't have long uphills and downhills we have rollercoaster trails with rocks on them. So by the end of the quick technical climb (when you're about to puke) the trail goes straight down, turns real quick and then back up again. You rarely even get a pedal stroke in during these downhills. You might have time to shift twice in that time and you don't want to be caught in you're middle ring when you're at the bottom of the steep climb. And it's not that I'm a slow rider. I'm usually in front.

    I run a 2x9 setup and it's rare that I even use the middle ring unless I'm cruising on the fireroads. I guess I need to look at more narrow tires

    It's pretty strange because I never had this problem with my Quasi or my Loco.
    sorry just thought it never helps to point out the obvious

    yeah i know the feeling..... do i risk throwing the chain vs risk missing the shift/drop the chain while shifting to granny???

    on my free ride bike i just adjust the lower stop until it gently rubs the chain. It's already a noisy beast with the chain guide so.... it bugs me.... but the chain stays on better.


    depending on what is going on back there at the cassette, you might try a spacer between the hub and cassette. silly sigestion... forget I said it.

    just some ideas.
    how is the dish on your year wheel. is it true? is there any play in the rear end?

  14. #14
    MC MasterShake
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    I don't think I can deal with the chain rubbing the stop sound. That sound bugs me more than the tire rubbing sound. I actually did try the spacer thing. That didn't work so well. The dish is solid. It's a fairly new DT5.1 and there isn't any wobble whatsever in it now. No play either. Everything looks solid except for the stupid tire/chain rub.

    I took a couple links out last night. We'll see if that helps at all. I think I'll just deal with it until this tire goes and just get a smaller tire. The Kenda's are big and wear quickly. I think I'll go for a Fat Albert next time. According to Shiggy's site it looks to be good bit smaller.

  15. #15
    MC MasterShake
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    Well I just got an e-mail from Titus. They spec 73x118 as the BB size for Moto-Lites. I'm pretty siked because my LBS actually has one in stock. I'll throw it on today and say goodbye to chain rub. Yeah!

  16. #16
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    come on Hobbit

    [. You might have time to shift twice in that time and you don't want to be caught in you're middle ring when you're at the bottom of the steep climb. And it's not that I'm a slow rider. I'm usually in front.

    the only reason you think you're not slow anymore is cuz you went and dropped a couple pounds with a new frame. I'd be in front too if I was riding with geriatrics. Geez!

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