Plow13

I have a 04 lemond alpe d'huez with a 50/34 compact and 11-27 in the back. I am going on a trip and we are doing some serious climbing. I'm no mountain goat as it is so i was wondering...Can i put on a mountain rear derailleur and and 11-32 cassette and it still work properly with my STI? Oh it's a 9speed cassette

LarDasse74

Yes. If you have Shimano shifters then you can swap to a Shimano mountain rear derailleur without a problem. THe only exception is if you have 8 speed dura-ace sti levers - these are not compatible with other groups.

Shimagnolo

The other exception is the 10s Shimano mtn RD.
They have drastically increased the cable pull and it is no longer compatible with any road shifters.

pacificaslim

Yes, just get any "9-speed" era Shimano mountain bike derailleur and it will work great with your road shifters. You may need to lengthen your chain.

(in case anyone is wondering, shimano has changed the geometry of their mountain bike derailleurs such that the new 10-speed mtb derailleurs don't work perfectly with 10-speed road shifters. But you can still use an older mtb derailleur from the 9-speed era with 10-speed road shifters).

edit: it took me so long to type my post that shimagnolo covered the last point already. thanks!

Shimagnolo

Agreed.
After seeing someone report that it worked, I upgraded the 9s parts on my touring bike with a 9s Shadow RD, a 10s 11-36 mtn cassette, and 10s road shifters, and they worked together like a charm.

pacificaslim

I'm a fan of the mix-match as well. On my 'cross bike I've currently got 10speed campy shifters with campy front derailleur but shimano xt 9-speed era "low normal" rear derailleur and 9-speed sram cassettes! Works great (though rather than use the alternate clamping style, i wimped out and put on the appropriate jtek shiftmate).

Chris_W

This change is becoming very popular. I hope it will urge Shimano to continue to produce a high-end MTB rear derailleur that works with road shifters. All their better 2011 stuff won't work, but at the moment the older 9-speed stuff is still readily available, when this ceases to be the case, I hope Shimano see the demand and release a special model of RD for this purpose. Maybe they'll then release a more road-appropriate cassette with closer spacing that still has the big cog, like a 12-32 or 13-32.

OK, I'll quit dreaming now.