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Chain Rub Near Rear Dropouts

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Chain Rub Near Rear Dropouts

Old 07-09-19, 05:28 PM
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Chain Rub Near Rear Dropouts

I'm having some some problems with my chain rubbing my frame when it's on the smallest sprocket. My bike's an old RB1 that I'm in the process of overhauling. I read over Sheldon Brown's article on frame/hub spacing, but I'm not sure if this will solve the problem. I measured my rear dropouts and they are a hair short at 129mm instead of the usual 130. I recently replaced my chain with a KMC 9 speed one. Not sure if this is the cause as I didn't notice this contact in the past. The chain isn't always in contact with the frame. At rest, there's probably about 1mm between them, but while moving, it'll bounce around enough to rub it. Any suggestions?



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Old 07-09-19, 05:42 PM
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Not sure what is going on with the nds of the axle, but you need an additional spacer on the drive side so the chain can clear the stay.
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Old 07-09-19, 08:36 PM
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Is there a spacer on the non-drive-side you could move to the drive side? Failing that, a thinner locknut and a spacer added to the drive side? Both these would call for re-dishing the wheel.
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Old 07-09-19, 09:10 PM
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The frame guys will see this as a frame issue. Rescallop the stay end a tad. Most wrenches see a component issue. Add spacers or use fewer cogs. Both are right. Andy
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Old 07-09-19, 10:55 PM
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If you think that's bad, try setting up a vintage mixte with a modern drivetrain. There's a whole 'nuther stay end to interfere with the chain if you don't build enough clearance into the axle.
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Old 07-10-19, 02:02 PM
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Ok, so I took one more pic to confirm. There's no spacer on the drive side, but one on the non-drive.

So the best way to handle this would be to swap the spacer to the opposite side and re-dish? Would it be better if I used smaller spacers on either side so the shift isn't so extreme? I probably only need a couple more mm's on the drive side to get the chain clear.

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Old 07-10-19, 02:07 PM
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Originally Posted by G_I_B_B_O_N View Post
Would it be better if I used smaller spacers on either side so the shift isn't so extreme? I probably only need a couple more mm's on the drive side to get the chain clear.
Yes, one other possible solution would be to run an 11 speed chain the narrower width may give the required clearance(or not) shifting the rear wont be an issue the front may be a little finickier(or not)
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Old 07-10-19, 04:35 PM
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Originally Posted by Andrew R Stewart View Post
The frame guys will see this as a frame issue. Rescallop the stay end a tad. Most wrenches see a component issue. Add spacers or use fewer cogs. Both are right. Andy
Agreed, except to the degree that there is not enough of the axle's lock-nut, that extends beyond the last cog, (or freehub locknut). Otherwise, no matter how much one indents the frame, he will still be clamping against the freehub, (or the chain when it's on the bottom ring), rather than the axle locknut when closing the qr. Can't be sure from the pics, but I doubt there's much.

If you really get satisfactory clearance by going halvsies on both sides, you might be able to skip re-dishing. Worth taking a look, perhaps...
Is it correctly dished now? Wouldn't be the first wheel that wasn't.

Last edited by Last ride 76; 07-10-19 at 04:45 PM.
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Old 07-10-19, 05:32 PM
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Originally Posted by Last ride 76 View Post
Agreed, except to the degree that there is not enough of the axle's lock-nut, that extends beyond the last cog, (or freehub locknut). Otherwise, no matter how much one indents the frame, he will still be clamping against the freehub, (or the chain when it's on the bottom ring), rather than the axle locknut when closing the qr. Can't be sure from the pics, but I doubt there's much.

If you really get satisfactory clearance by going halvsies on both sides, you might be able to skip re-dishing. Worth taking a look, perhaps...
Is it correctly dished now? Wouldn't be the first wheel that wasn't.

The Op never said his freehub contacts the drop out, only that his chain when in the small cog contacts the end of the DS seat stay. His photos confirm this although there isn't a good shot of how far the DS lock nut is extending out past the cassette/lockring. Enough for this to not be mentioned though.

I was only trying to bring a different view of this problem. Andy.
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Old 07-10-19, 11:37 PM
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Thanks for the help everyone. As this might require some consideration to handle properly, I decided to see what my LBS would say today.
Initially the mechanic was worried that re-dishing too far would put it out of shimano's spec, but ended up getting it done the same day. He said the wheel was off center (to the frame) to begin with and ended up adding a small spacer to the drive side and re-dished it. He said it was going to be a hair off center just due to the wheel being matched with this old frame, but it was almost perfect and the alignment was much improved from before. There's about a 3mm gap between the frame and chain now, so no contact. Only charged me $16 and it's dished perfectly, so I'm happy I passed this one on to them.

Thanks again for the help.
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Old 07-11-19, 12:02 AM
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Is that a real 9 sp chain? Says Z chain. Usually KMC 9 sp will have something else on it.
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Old 07-11-19, 12:08 AM
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Originally Posted by trailangel View Post
Is that a real 9 sp chain? Says Z chain. Usually KMC 9 sp will have something else on it.
What does this even mean?

It's a ******g KMC Z-Chain 9 speed.
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Old 07-11-19, 12:11 AM
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Old 07-11-19, 02:28 AM
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If you can put a couple of @ 1mm washers on the drive side - and you may have to ream them out a bit first so they'll fit - that worked for me with an old frame spaced out to accept a 130mm wheel.

Don't mind the cleanliness of the components here... what some people call "dirty", I call "patina" This is my "old heavy" Bianchi Sprint 76 , which is not far off being a ratrod bike, with a modern 9 speed wheel and DT friction shifters.



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Old 07-11-19, 12:55 PM
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Originally Posted by G_I_B_B_O_N View Post
Thanks for the help everyone. As this might require some consideration to handle properly, I decided to see what my LBS would say today.
Initially the mechanic was worried that re-dishing too far would put it out of shimano's spec, but ended up getting it done the same day. He said the wheel was off center (to the frame) to begin with and ended up adding a small spacer to the drive side and re-dished it. He said it was going to be a hair off center just due to the wheel being matched with this old frame, but it was almost perfect and the alignment was much improved from before. There's about a 3mm gap between the frame and chain now, so no contact. Only charged me $16 and it's dished perfectly, so I'm happy I passed this one on to them.

Thanks again for the help.
Always love a story that ends well.
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There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
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