Mountain Biking - Will 7spd RSX rear derailleur work with 7 speed Mt. bike.

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bigp399
08-02-04, 09:43 AM
I have a pretty low end Trek (4100) whose rear derailleur and hanger are pretty much toast after a strange mishap. It has 7spd components on it presently, I was wondering if I could use my old 7 spd RSX road rear derailleur on it, if not for single track then at least for campus riding and the like. My instincts tell me this won't work, but my wallet hopes that it would. Any advice is welcome. Thanks.

a2psyklnut
08-02-04, 11:40 AM
Maybe yes, maybe no. What is the size of your rear cassette? IOW, how many teeth does the big cog have?

A road cassette has a tighter gear ratio, so the cassette will have a much smaller big cog. Correspondingly, the rear derailleur for a road bike has a much shorter cage on it, so when you shift into the big cog, it will do so easily and will also provide for adequate chain length.

Most mountain bike derailleurs are available in long cage and short cage.

Compare the two derailleurs if the RSX is similar in size to the damaged one it may work.

BTW, the "cage" is the metal portion between the two jockey pulleys. O.k., the jockey pulleys are the two little chain roller guides of the read derailleur. Does that make sense???? I hope so, because I'm getting a headache trying to explain.

L8R
Hopper
08-03-04, 03:03 AM
Heaps of the really good, and weight conscious DH riders in my local series run road derailleurs for there weight and presision shifting.

Sometimes funny seeing a hardcore rider with an M1 or V10 trying to save that little bit of weight on such a big bike.

But back to your prediciment(sp) it very well could work, but you may need to try it.