sean1515

Hello, I have a Cannondale Caad X Cyclocross bike with Shimano 105 components. I want to put on a 11-34t MTB cassette for some touring trips I want to do with weight and up steep hills. I have a Shimano Deore 11-34t cassette, and I know that will not work with my Shimano 105 rear derailleur. I need a new long cage derailleur that works with the capacity of a 34t cassette, and also would be compatible with Shimano 105 road shifters. I know a 11-32t cassette would open more doors in terms of derailleurs, but I like the idea of having the extra bit of gear with 34t. The deore long cage looks promising, but I have heard it may not work with 105 shifters. Does anybody have knowledge or suggestions for my idea?

jimc101

Which 105? 5500, 5600, 5700 or 5800? and which Deore M530,590,610 etc?

If 10 speed 105 (5600 or 5700) can you wait till Tiagra 4700 comes out (due this/next month), which out the box has a 34t cassette & RD option?

pickerd

Hi
I guess you are looking for a long cage rd? Although you may get away with a medium cage if you are running a double chainset rather than a triple - this may be your preference given what I have to say below?

As regards a long cage rd .... I tried a 10 speed MTB rd with 105 STI levers and it didn't work. It would only shift 9 cogs for 10 clicks of the lever - it never reached the top sprocket regardless of adjustment.

The answer to use a 9 speed rd with 10 speed STI levers.
I have tried an Acera and now a RD M591 - both work fine.

Tim_Iowa

pickerd is absolutely correct. Shimano changed the pull ratio for 10-speed (and 11-speed) MTB rear derailers, so they no longer work with road shifters.

You can use a 9-speed MTB rear derailer, which has the same ratio as all road shifters. The shifter controls the speeds/indexing; the RD doesn't care (so long as the ratio is the same).

My favorite RD for this situation is the XT M772. $80 new, much cheaper used.