only have medium in stock at CRC . Is that because most of us use a long?

I have searched for a mech length thread and cant find any advice on which to but.
Thanks

It’s based on the number of teeth difference between the biggest and smallest possible ratio’s and thus how much ‘slack’ the mech has to take up at the extremes.

As a rule of thumb – if you’re running a triple you need a long cage mech.

thanks i will get a long

Yeah, Shimano will say that if you run a triple then you need long cage. However if you never run big-big sprocket combinations then a medium will be fine. I run all my bikes with a medium cage and an 11-32 cassette and don’t have any problems.

You don’t need a long. The Shimano Shadow “medium” cage is very long- about the length of an old long mech. You only need the Shadow long (or rather “extra long” if you’re running a 36T cassette out back with a triple of run big touring chainrings.

ah, sorry OP, I didn’t know that 🙁