Can anyone tell me what the capacity of the Shimano RD-M750s are? Per this tech doc there are two versions; a medium cage and a long cage. I have a used one of each on hand.

I’m trying to replace a RD-M772-GS (mid cage shadow) that is worn out (play in the pivots causing ghost shifting). I know that the M750 SGS (long cage) will work, but I think that I’d need a longer chain.

I’m thinking of going 2×10, so I want to avoid spending anything at this point if possible.

chain length is set without the derailleur. It is just the capacity that matters for the RD.

If you click the next PDF over on the techdocs page it will have the installation instructions with the capacities.

Installation instructions were what I needed. They show that the shorter cage M750 has the same capacity (33T) as my current one. So I guess I’ll try the short cage since it should work.

Thanks andyl.