jmeans53

I recently bought a cx bike and have broke my rear derailleur (Shimano Tiagra) on a pretty challenging trail ride. After doing some research, I thought it would be a good opportunity to upgrade and I also read some posts about switching to a MTB derailleur. I have a new Shimano RD-M772 XT Shadow. I guess I don't fully understand and am having issues b/c I can't shift to either gears 1 or 9 with this derailleur. Do I need to put a different cassette on? Currently I have a SRAM 9-speed, 11-26T. Is there any other modifications I need to make for this to work?

Crankset: FSA Vero Aluminum Forged crankarms, 50/39/30T Chainrings, 130BCD
Shifters: Shimano Sora 9-speed

I'm new to this cx thing (really I'm new to cycling in general) so I appreciate everyone's thoughts/help.

dnuzzomueller

In general switching between any single manufacturers stuff is alright with a few exceptions.

In your case as long as the new derailleur is not labeled as being Dyna-Sys then you should see no problem going to a mountain derailleur. The one thing a mountain derailleur will give you that you could take advantage of IF you were to swap to swap to a different rear cassette is a larger range so if you wanted to you could get something like a 11-32 (hypothetically speaking, you still need to check the max range and gear capacity on your derailleur)

If I am wrong though about any of this someone is free to correct me (As I know someone will )

fietsbob

neither 1 nor 9? suggests the limit screws, Hi & Low, are too tight. and the travel is limited...

LarDasse74

The derailleur is compatible. I can't say why the deraileur is not working, but I have two suggestions for you -

1. Takethe bike to a shop and have them check the deraileur hanger alignment. If it is misaligned by only a tiny bit your shifting will be crap, and possibly cause your deailleur to get stuck in the spokes and torn off.

2. Go to parktoool.com and follw their step-by-step instructions on setting up a derailleur. If the hanger alignment is correct and the derailleur is compatiblle with the shifters and cogs (yours is 100% compatiblle, by the way) then setting up a derailleur is dead simple if you follow their instructions.

jmeans53

Thanks for the replies...I'm glad to know that everything is compatible...now I just have to figure out what I've done wrong

Bezalel

I wouldn't reccoment using a Mountain Derailleur with a road cassette. In the lower gears the guide pulley will be further away from cogs and shifting won't be as smooth.

jmeans53

If I do decide to go with a mountain cassette what type should I use? I've read some poor reviews on the shimano m770 but I don't want to spend the $$ for the m970. Are there any alternatives? Does anyone have experience riding either of the two I mentioned?

Shimagnolo

You didn't adjust the Hi and Low limit screws.
In my recent experience, Shimano has been shipping RD's with both cranked in, so both need to be backed out when adjusting at installation.
(I just installed an M772 yesterday).
And due to the relatively small size of your large cog (compared to a mtn cassette) I am sure you will also need to adjust the B screw to bring the upper pulley 5-6mm away from the large cog in the lowest gear.

CCrew

It'll work just fine though.

jmeans53

Thanks for the help...I adjusted the limit screws and it's shifting great (so much better than the tiagra that was on there originally).