120 hub in a cross check (132.5mm)- Mtbr.com
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  1. #1
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    120 hub in a cross check (132.5mm)

    I have a 120mm hub in my cross check frame which has a frame spacing of 132.5, so I bended the frame a little and added some spacers to fit it all.
    But now, I'm facing some chain slack, but not on all positions of my crank. So in some position the chain tension is fine, but in other positions the chain is to loose.
    I'm wondering if bending my frame can cause this problem? I'm sure that my sprockets are fine (not oval or something).
    I don't understand why I can't get the correct chain tension, and keep facing this problem. First I thought that my crank's where not that good anymore so I replaced them.

  2. #2
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    I ran a 120 hub in a Crosscheck frame for years, I added a 5mm spacer on each side since it was a solid-axle Surly hub this was pretty simple to fit in underneath the locknuts. Works fine. I ran a standard Shimano road crank with the ring in the inside position.

    Intermittent loose/tight on a SS or fixie setup is normal, and is not caused by a slightly off chainline. Cogs and Chainrings are not perfectly round, and they are also not perfectly oriented around their axis of rotation. As long as you are using SS-specific cogs and chainrings with a tall tooth profile not designed for shifting, you adjust so the tightest point is not binding on your bearings, and ignore the loose spots. If it seems really bad or you want to improve it, you can try "truing" the chainring's bolt-on position by slightly loosening the chainring bolts, rotating the cranks, and adjusting the ring position at the tight spots as good as possible. Some people tap the ring, the technique I like is to grab both sides of the chain halfway between the ring and the cog and squeeze to apply rearward pressure where the tight spot is while tightening the chainring bolts with the other hand. Normally this is too much work and I just ignore the loose spots.

  3. #3
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    or maybe he "bended" his chainstays unevenly and is now facing not only a damaged frame, but also an off-centered wheel that in all likelihood isn't running perfectly inline with the front wheel either.

    t-8one, in the future, just use spacers like canyonrat suggested, don't bend frames.
    a couple mm is ok, like say 130-135 or 126-130.
    but you just reefed the metal collectively over 12mm. (132.5 to 120)
    that's a huge amount of movement for something that was designed to NOT be moved in that direction.
    If steel is real then aluminium is supercallafragiliniun!

  4. #4
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    Make sure you align the dropouts too. I recently cold set (bent) the stays on my old singlespeed from 126 to 135, and then dropout misalignment messed up the drive side bearing in the rear hub.
    I just used a piece of threaded rod to approximate the fancy park tool version.

  5. #5
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    Ok, tnx I'll try to find out if my frame and/or chainstays are bent to much if there is no wheel in the frame.
    The axle in the current wheel is just a little to short to fit for 130/132.5mm with the spacers, is it possible to replace it with a longer axle?
    It's a wheelset that original came from a Specilized Langster.

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