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Replace Rear Derailleur
I bent my rear derailleur and wheel during a fall. :-( I don't know much about repairing bikes, but i need to get a new rear derailleur. What kind of rear derailleur must I purchase for an 18-speed mountain bike?
Hard one to answer without more information. The derailleur is part of a system of components that need to match with other things on the bike. If you can trade like for like that would be the easiest way to go. Otherwise we would need to know more about the components on your bike to make any recommendations.
What information can I give you to help me find the correct part? This bike is a p.o.s. from Toys R Us. I am trying to buy a rear derailleur online to save money. And my neighbor said he can fix it for free. Bike shop wants $40/hour labor and their cheapest derailleur is $70. I don't have the means to pay a bike shop. It would be cheaper to buy a new bike.
The main questions are do you indexed (click) shifting where the shifter pops into place, or do you just move the shifter around until it's in the right spot? Then: what brand shifters do you have, what brand is the current derailleur, and does the deraileur have a hook that hold it on (like this: ) or does it screw straight into the frame (like this: )

I don't know for sure that either of these would work. But you should be able to get something for <$20.

Is the wheel OK? If that needs to be replaced, more expensive than the derailleur.
Twist shifters that I move, I assume are made by Power because Power Index System is the maker of the rear derailleur that has a hook. I don't know who Power is. The bike is an off brand called Rallye.

I bought a new wheel from the bike shop for $53. That was before I saw the bent derailleur that can not be bent back into position.

Appreciate your help.
If the shifter does not have specific clicks for each gear position (click 1>gear1, click2>gear2, etc.) you can use any derailleur that has a hook. If the shifter does click into place for each gear, you can probably use just about any, but might be safer with a shimano brand shifter. Pretty much everything low end uses shimano compatible. Using the "wrong" kind would mean that it might be hard to get the shifting adjusted to work well. Good luck
Thanks DaveM. My shifter does have specific clicks. I was thinking of using SRAM, but if you recommend Shimano I'll try them. Along with the rear derailleur, do you think I should change the left and right shifters?
A SRAM derailleur may be fine. I'm just guessing on compatibility. But I wouldn't buy something better than just a cheapo one unless you're upgrading other parts. It won't make any difference in how it shifts.

I wouldn't change shifters unless there's something wrong with what's on there. This is not a bike to "upgrade". It just won't pay off on a bike like this. If you want a better bike, start saving up and buy a better bike from a real shop. Replacing parts one at a time is much more expensive than just buying something decent. And you get a new bike with a warranty and a shop that will take care of you, etc.

(My only exception to the anti-upgrade attitude is brake pads and tires. These are worth buying good quality once the ones you have wear out.)
What speed do I get? SRAM has 9 and 10 speed rear derailleurs.

I have a 30-year old Schwinn Mountain Bike, too. It's to big and heavy. :-)
You want a 6 speed derailleur. Don't bother with a SRAM. It won't have the mounting hook.

Something like:


You might just call local bike shops and ask if they have a cheap rear der with a hook. Most shops have something like this on hand.
Once again, thank you DaveM. You have been of great help during my time of need. Have a pleasant evening.

this will work well with what you have.

SRAM rear derailleurs required different shifters.
I already ordered Derailleur Shimano Rd-Ty18 Tourney Gs 6-Speed, W/Bracket.

Will this work okay?
(09-09-2011, 04:59 PM)sha2nanigans Wrote:  I already ordered Derailleur Shimano Rd-Ty18 Tourney Gs 6-Speed, W/Bracket.

Will this work okay?

Yes, should work with no problems. It is old stock, discontinued years ago, but it is a fine rear derailleur.

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