Evening all,

How do you know which length rear mech to run?? It’s going on a 2010 Heckler.

Cheers
Carl

How many rings up front?

And what cassette on the back?

Cassette doesnt really make a difference. short cage should work with any cassette.

If your running 1×9 then go for a shortcage mech, otherwise a medium would be ok i think

3 up front
Sram PG980 11-34 but looking at getting a PG980 11-32

Preferably long with 3 up front. Med if you don’t go too mad with gear combo’s.

Cage length is purely about capacity (nothing to do with rear cassette). For a conventional triple up front, you need a long cage mech, for a single ring a short cage and for a double, somewhere in the middle.

Each mech will have a maximum rear cassette size it can cope with. This is a separate parameter to cage length. Most MTB rear mechs can cope with 34t, shadow mechs can apparently cope with the new 36t cassettes, although I’ve not personally tried this.

Cheers

Long it is