Bottom Bracket Axle Width- Mtbr.com
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  1. #1
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    Bottom Bracket Axle Width

    I might try going back to square taper as I've picked up some white industries cranks.

    I just wanted to ask about bottom bracket axle length, since they come in a wide variety of sizes.

    I'm guessing if you've converted a freehub to singlespeed it kind of doesn't matter in terms of chainline, since you can tweak that at the other end, but my only concern would be about flex on a longer axle, and how much to spend. Does it make a huge difference? I'm sure, as with all thing s that not all makes are created equal , and without spending a fortune I'd like to gauge what people thought were good BB shells.

    cheers chaps,

    Pete
    Last edited by Pudgerboy; 03-12-2007 at 04:08 PM.

  2. #2
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    Quote Originally Posted by Pudgerboy
    I might try going back to square taper as I've picked up some white industries cranks.

    I just wanted to ask about bottom bracket axle length, since they come in a wide variety of sizes.

    I'm guessing if you've converted a freehub to singlespeed it kind of doesn't matter in terms of chainline, since you can tweak that at the other end, but my only concern would be about flex on a longer axle, and how much to spend. Does it make a huge difference? I'm sure, as with all thing s that not all makes are created equal , and without spending a fortune I'd like to gauge what people thought were good BB shells.

    cheers chaps,

    Pete
    Yo Pete,

    I've never used anything but square taper. (Okay, I lied. I have an ancient Bullseye crank, too.) Anyway, square taper is bingo, IMO. But spindle length varies more by crank than by frame. Well, sometimes.

    I recently busted my 10 year old Caramba cranks, which employed a 113mm spindle. So I ordered some High Sierra Cycles custom cranks, which arrived complete with a 113mm spindle from the manufacturer. Well, with the 113mm spindle, the new cranks hit the chainstays and so did the spider. Bad. So I ended up having to use a 122.5mm spindle. (I ~might~ have been able to get away with a 118mm spindle, but anyway...) My point is this: same frame but different cranks in this case required almost a 10mm difference in spindle length.

    So check with your crank manufacturer for their advice on spindle length.

    As for BB recommendos, I've never been dissatisfied with a Shimano UN72. The UN73, with its plastic adjustible cup, is almost as good. Whenever I get one of those, I just reuse the aluminum adjustible cup from the old UN72.

    --Sparty
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    We don't quit riding because we get old.
    We get old because we quit riding.

  3. #3
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    the white industries cranks usually use a 113mm spindle, although your frame may need a different length. It really depends on the bike, but a 113 or 115 is a good place to start with that crank.

  4. #4
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    Quote Originally Posted by Sparticus
    So check with your crank manufacturer for their advice on spindle length.
    +1. Guessing sucks when you're wrong and have to return BBs, do this and save yourself some grief.

    Quote Originally Posted by Sparticus
    As for BB recommendos, I've never been dissatisfied with a Shimano UN72. The UN73, with its plastic adjustible cup, is almost as good.
    +1, and you can't beat the price for the quality.
    pete

  5. #5
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    Hi Guys,

    Thanks for all your replies, they're really helpful. Its funny, as previous to my current external bearing hone cranks, I have only ever run square tapers - but never as a singlespeed. So the notion of chainline never even cropped up. I'm thinking that as i'm running a converted back wheel with spacers ill have a bit of room but ill just have to watch it clears the frame at the crank end and i'm running a slightly fatter chain too. Im trying to find some info on the WI cranks but havent turned up anything so far. The WI website seems to be different than the last time i looked and looks a bit like a low res product catalogue with not a lot of info.

    Cheers!

    Pete

  6. #6
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    I'd like to follow up on this thread a bit, but with relations to some Shimano XT square Taper Cranks vs. some XT hollowtechs.

    Right now I've got a 68x113mm bb in my Inbred 29er with XT hollowtech cranks (but the pedal threads are in crappy shape on them), but I've been considering using a set of XT square tapers (same bolt pattern too) instead - but the only 68mm bb I have is a 107mm spindle. will that 6mm of difference be too much? I think it could work, but was wondering if anyone could chime in. What would be the next longest 68mm Shimano bb to look for if you think the 107mm one would be too short?

    Thanks in advance!

    Mark

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