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Old 07-18-06, 08:39 AM   #1
philaaay
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Questions on my Trek Alpha Aluminum 6500...

I recently bit the dirt road and bent my rear derailleur. The bike still rides but when I ride hard downhill, the chain pops in and out as well as the rear derailleur messing up my shifts. Ultimately, in the end, the chain got locked by the messed up derailleur and ended up snapping my chain. My bent derailleur is a Shimano Deore LX. The guy at Performance Bike says that he can "bend" it back into shape but I'm not sure if that'll be the best way. Also, I have a spare rear derailleur that I took off my old Specialized (a Shimano STX) and I'm wondering if that will be compatible with my Trek. Also, I fear that I may have bent my front rim because when I spin the wheel, it kinda rocks slightly to the left. Any help will be greatly appreciated! Thanks!
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Old 07-18-06, 08:43 AM   #2
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1. You can have the derailleur bent back in place. This often works fine, but not always.
2. The old derailleur probably won't work if you have a 8 or 9 speed cassette. I could be wrong.
3.Wheels can be trued. Your LBS can true that wheel up to near perfect for you. Or you can learn to do it yourself with a spoke wrench.
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Old 07-18-06, 08:58 AM   #3
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Is the derailleur bent or the hanger on the frame?
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Old 07-18-06, 09:21 AM   #4
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it looks to be the derailleur...
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Old 07-18-06, 12:22 PM   #5
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[QUOTE=Jason222
2. The old derailleur probably won't work if you have a 8 or 9 speed cassette. I could be wrong.
[/QUOTE]

The derailer is a robot. It just does what the shifters tell it to. An old 7 spd STX should work well enough with an 8 or 9 spd cassette.

But if you, philaay, crashed hard enough on the derailer side to bend the derailer, I'd suspect that you toasted the hanger. Look and see if it is still parallel to the frame. If not, you'll need a new hanger.
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Old 07-18-06, 03:50 PM   #6
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The hanger is supposed to bend before the derailleur. I'd make sure that it isn't just the hanger that is bent. They are easily straightened or replaced.
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Old 07-18-06, 07:29 PM   #7
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Quote:
Originally Posted by cyccommute
The derailer is a robot. It just does what the shifters tell it to. An old 7 spd STX should work well enough with an 8 or 9 spd cassette.

But if you, philaay, crashed hard enough on the derailer side to bend the derailer, I'd suspect that you toasted the hanger. Look and see if it is still parallel to the frame. If not, you'll need a new hanger.
I thought that this was true for 8/9/10 speed parts, but not for the older 7 spd parts -- as the overall width of the 7spd cassette was different.
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Old 07-19-06, 08:19 AM   #8
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Quote:
Originally Posted by downbycoleslaw
I thought that this was true for 8/9/10 speed parts, but not for the older 7 spd parts -- as the overall width of the 7spd cassette was different.
Generally, the cable throw is determined by the detents in the shifter. The derailer doesn't really care what it's attached to...as long as you don't mix brands. Some Sram derailers require different cable throw (Grip shifters) while some are made to work with Shimano.

I have put lots of very old derailers on bikes that have modern shifters without problems. If I do have problems it's usually because the derailer is worn out, not because of cable issues.

As with most things on a bike, try it. If it doesn't work...well, try something else.
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Old 07-19-06, 08:33 AM   #9
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geesus what did you hit to bend your detrauiler? Mine is LX too and it's so strong I can hang my bike on it.
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Old 07-19-06, 02:25 PM   #10
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Thanks for all the input guys! For Jiiiim, I was haulin' @$$ on a downhill where I bit the dirt and there was a log on the ground that out of all places, hit my derailleur. The physics of this is all very messy, but I must say that I'm glad I didn't go tumbling down the cliff.

As for the derailleur, my friend at Performance Bike is checking it out, to see if my old one will work, and if not, I'm picking up a new Shimano Deore LX for $50.00. I'm trying to get most repairs done before I head out again this weekend on Whidbey Island - any Washington heads here?
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