Rear Wheel Troubles...

[navybeetle]

I posted this on the general discussion thread but then realized there was a maintenace section. Anyway, I am getting back into this sport. I have a mountain bike that I use on the road, on trails and anyplace else I have to. Yesterday when climbing my chain went right over the largest sprocket (?) closest to the spokes. This happened twice. I was able to get it back on. Once I got home I notice a little play in the chain. On the same ride I noticed my rear brake was rubbing on my wheel, only at a certain part of the wheel. So, I think my rear wheel may be off kilter. If you can help me or know a good book/site that can help me with little issue like this I would love to hear about them. My bike shop is downtown and I can only get there by car (until I get in better shape!), there is a shop down the street but I did not buy my bike there and don't want to dole out unnecessary $$$$. I want to learn to fix it myself. Thanks .

[tulip]

Were you in your big front chainring by any chance? If so, being in the big front/big back combo is a no-no, and can lead to the chain jumping off. You should shift to the middle or smaller chainring in front before shifting to the largest rear sprocket while in the biggest front chainring.

If this does not apply, then your chain may be stretched or your derailleur may need adjusting. You can start by cleaning and lubing the whole drivetrain. Sometimes that will help all by itself.

Be sure to check that your rear wheel is properly seated and is not misaligned in the dropouts. It might be best to remove the wheel and reinstall it fresh. Your brake might be crooked, too. Cleaning the drivetrain will help regardless.

[Thorn]

Tulip's right....clean and lube the drive train and make sure the rear wheel is in straight. If it is offset it could be causing your problems.

But look at topics on the rear derailleur limit screws (e.g., http://www.parktool.com/repair/readhowto.asp?id=64 )

If your bike does not have a spoke protector (aka dork disk) having the chain jump over the largest cog and into the spokes can destroy your wheel. The chain will wear on the spokes, weakening them leading to failure.

So, Park Tool has a good site. The BicycleTutor.com site is also good. Doing your own repairs is not just fun but also gives you a confidence on the road knowing you can fix it if you have to.

[navybeetle]

Were you in your big front chainring by any chance? If so, being in the big front/big back combo is a no-no, and can lead to the chain jumping off. You should shift to the middle or smaller chainring in front before shifting to the largest rear sprocket while in the biggest front chainring.

If this does not apply, then your chain may be stretched or your derailleur may need adjusting. You can start by cleaning and lubing the whole drivetrain. Sometimes that will help all by itself.

Be sure to check that your rear wheel is properly seated and is not misaligned in the dropouts. It might be best to remove the wheel and reinstall it fresh. Your brake might be crooked, too. Cleaning the drivetrain will help regardless.
I think I was in my big front chain ring,maybe the middle. Good to know about the big front/big back combo... I had no idea. The chain did seem "loose" that was one of the first things I looked at, it had alot of play. I agree, the wheel may be out of alignment. I am getting great feedback and i really appreciate it.

[DebW]

Check for damaged spokes behind your cassette. If some spokes are bent or gouged, those spokes should be replaced and the wheel trued. You most likely need to adjust the lower limit screw on your rear derailleur to prevent this happening again. And if the chain is worn/stretched, consider replacing it.

[navybeetle]

Check for damaged spokes behind your cassette. If some spokes are bent or gouged, those spokes should be replaced and the wheel trued. You most likely need to adjust the lower limit screw on your rear derailleur to prevent this happening again. And if the chain is worn/stretched, consider replacing it.
I have a plastic thing between my spokes and the sprockets (?) so I don't think the chain hit the spokes. I just bought this as a refurbished bike, used but all fixed up. I will check the lower limit screw, I dont know what a worn r stretched chain looks like. Thanks for your help.

[Owlie]

Here's the Sheldon Brown article on chains:
http://sheldonbrown.com/chains.html#wear
Scroll down a bit to get to the part about chain wear.