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Old 02-13-08, 12:40 AM   #1
Albinus
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Upgraded cluster now wheel misaligned?

G'Day guys!

I've recently replaced all the running gear on my old, but reliable MTB. Absolutely every bit of running gear has been changed (yes, may have been cheaper to buy a new bike but I love the frame). My problem is now that the rear brakes seem off center, no amount of adjustment can keep them off the rim on one side. I've upgraded from a 13-28 5-speed Shimano SIS cluster to a 7-speed Shimano Megarange 11-34 model. The wheel also seems a little harder to place in the dropouts (presuming slightly wider since the upgrade). My question is, do I need to dish the whole rear wheel one way by tightening the spokes on one side and loosening them on the other, or do I need to "persuade" the frame to widen somehow?

I've resurrected the front wheel - the V-Brakes are within 2mm of the rim on either side and yet don't touch the rim during normal operation (only a negligible lateral wiggle), but the rear seems to be stubbornly over one side, requiring some very tricky counter-adjusting on the rear brakes (and keeping them looser than I'd like)

Any ideas gratefully received

[EDIT] Should note that I upgraded from a yum-cha cheap set of post V-Brakes that were a PITA to adjust, to a brand new set of alloy bosses with studs instead of posts. Don't think that's got anything to do with it though?
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Old 02-13-08, 10:03 AM   #2
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Since the 7 cog "stack" is wider than the 5, you wheel has been moved to the non drive side. You'll have to dish it toward the drive side to re-center it..
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Old 02-13-08, 08:04 PM   #3
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So to dish the wheel, do I need anything special apart from a spoke key and patience? Should I just loosen all the spokes on the non-drive side by a third of a turn, then tighten the drive side up by the same amount? Then repeat as necessary?
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Old 02-14-08, 03:04 AM   #4
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If it were me, I'd try and centre the brakes on the wheel as it is. I'm not an experienced wheel builder, and redishing a wheel sounds too drastic. Maybe you could add a bit more of a spacer on the non-drive side. Or fiddle with the spacers on the brake blocks.

If you ignore the brakes for the moment, how far off centre is the wheel rim in relation to the frame?
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Old 02-14-08, 07:02 PM   #5
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The rear brake arms are on such an angle that they look like a slight trapezoid. Instead of both brake arms being vertical when the brakes aren't applied, both are bent to one side with one being drastically moved over. I've also had to pull the brake arms off and place them on the next hole down on the brake bosses to provide additional spring loading on one side, and not to retract them so much on the other side. Also one of the adjustment screws is all the way in and the other is all the way out. With this setup I can get the brakes working, but they are really, obviously off center - the perfectionist in me would like to see the wheel centred more in the frame

I needed to take a thin spacer off the non-drive side of the axle to place on the drive side, so the 7th sprocket when engaged doesn't get the chain rubbing on the drive side dropout. I'm wondering whether I should get another thin spacer to place on the non-drive side, although that would mean it would be very tricky to get the rear wheel back in the spacing between the dropouts.
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Old 02-14-08, 09:14 PM   #6
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Quote:
Originally Posted by Albinus View Post
So to dish the wheel, do I need anything special apart from a spoke key and patience? Should I just loosen all the spokes on the non-drive side by a third of a turn, then tighten the drive side up by the same amount? Then repeat as necessary?
Yes - that is what you do. You can check that the dishing is correct by putting the wheel in backwards, and the rim will be in the same position relative to the brakes. If you have a steel frame, Sheldon Brown's website tells you how to spread the rear traingle.
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Old 02-18-08, 12:54 AM   #7
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OK - here goes

After following the advice of one of my online buddies who incidentally happens to be a member here, I spaced the wheel so it was exactly in the middle of the frame. Nice! But for some bizarre reason the brakes are still leaning heavily to one side, and I have no idea on what I'm doing wrong. This is a photo taken of the rear brakes, adjusted the most they can to one side!

Any further ideas?

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Old 02-18-08, 08:12 AM   #8
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1. I'm thinking that when you installed the 7 cog freewheel you added a washer or something to the right side of your axle. Try to find one the same thickness on the left side and take it out. That'll make your wheel fit more easily in the dropouts.

2. Your wheel is out of dish due to the freewheel change. Redishing is easier than you think. Loosen every left side spoke 1/4 turn and tighten every right side spoke 1/4 turn. If you're careful and accurate about doing that, it won't affect the wheel trueness or anything else. After doing that test fit your wheel in your bike frame and flip it over the other way. When it looks even, you're done.

3. Adjusting the brakes to fit your out-of-dish wheel and spreading the frame to fit a wheel that has been modified to be too wide - those are examples of the tail wagging the dog.
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Old 02-18-08, 08:19 AM   #9
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Albi, I have seen more than a few frames that have the brazed-on bosses off-center from the factory.

If the wheel is centered, the only other fix for the brakes is to swap the washers around. Look closely and you will see that there is a thick and a thin pair of domed washers. Swap them around until the brake arms are relatively upright and parallel. Sometimes you can add a few extra to get the brakes straight. I save the extras when I swap pads to fix this very issue.
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Old 02-18-08, 09:48 AM   #10
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1. I'm thinking that when you installed the 7 cog freewheel you added a washer or something to the right side of your axle. Try to find one the same thickness on the left side and take it out. That'll make your wheel fit more easily in the dropouts.

2. Your wheel is out of dish due to the freewheel change. Redishing is easier than you think. Loosen every left side spoke 1/4 turn and tighten every right side spoke 1/4 turn. If you're careful and accurate about doing that, it won't affect the wheel trueness or anything else. After doing that test fit your wheel in your bike frame and flip it over the other way. When it looks even, you're done.

3. Adjusting the brakes to fit your out-of-dish wheel and spreading the frame to fit a wheel that has been modified to be too wide - those are examples of the tail wagging the dog.
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From the picture your wheel appears to be way out of dish, assuming the axle is mounted squarely in the frame.
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Old 02-18-08, 11:36 AM   #11
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Take a brake arm off and put end of the return spring in the next hole on the frame. Then do final adjustment with the little screws on the side of the arms near the pivot points.
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Old 02-24-08, 06:59 PM   #12
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Well here's the end result, no dishing required:

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