Bicycle Mechanics - Bent dropout or something else?
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07-22-08, 01:56 AM
A few minutes ago i was re-attaching my rear wheel and noticed that it was rubbing the brake. When i looked down to align it using the chainstays as a guide it appeared to be centered. Basically, it seems like the wheel is leaning to the left a bit. I spent a lot of time looking over the frame and dropouts and nothing looks bent to the naked eye.
Any guesses or suggestions?
EDIT: The "lean" is pretty major. It's actually pushing the left brake over as far as it will go.
07-22-08, 02:17 AM
Does it change when you spin the wheel?
07-22-08, 02:33 AM
no....the reason i took the wheel off in the first place was to true it
07-22-08, 03:51 AM
How much did you have to true it? Could the "Dish" be off? i.e. the hub is now set to far to one side?
07-22-08, 11:57 AM
The wheel was in terrible shape. It took quite a while to get it corrected. I'm not sure what you mean about the hub or dish. Could you explain how to check if there's a problem with it?
Thanks for the help
07-22-08, 12:19 PM
Dish is the lateral positioning of the rim over the hub and axle. The rim should be centered between the axle-ends, which means it won't be centered over the hub-flanges. To test this centering, take out the wheel and flip it around (swap left-right sides). The cogs will be on the left and the chain will be resting on the hub-shell.
How centered is the rim now? I take it you have horizontal dropouts if you can adjust centering between the chainstays. With the wheel flipped and centered between the chainstays, how are they between the brakes? If they are rubbing on the other side, then the wheel needs to be dished (centered between axle-ends). If they are still rubbing on the same side, the rear-triangle may be mis-aligned or the brakes may be off-centre.
07-22-08, 12:24 PM
If you turn the wheel around in the dropouts, and the rim pushes the brake in the other direction, your wheel is out of dish, which means that the rim is not centered properly in relation to the hub.
Check out Sheldon Brown's website for further (better) explanation - http://www.sheldonbrown.com/gloss_da-o.html
Edit: DannoXYZ beat me to the punch...
07-22-08, 12:34 PM
You get the prize!
When I flipped the wheel, it rubbed on the opposite side. I did a search for dishing and the threads that came up make it seem pretty complex and precise.....I guess I'll just take it to the lbs. Thanks for the detailed responses Danno and Malthus.
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