Mech sizing

David Lund

Im running two chainrings up front with an e13 bash guard, 9 speed cassette at the back 11 - 34t.
Which shimano mech size so i want?
Extra Long?
Long?
Medium?
Why do they have to be different to other brands :evil:
Cheers in advance
David

supersonic

You need to find out the capacity of the mech, and compare it to your set up.

You need:

34-11 plus the difference in teeth of the rings.

David Lund

Right youve confused me even more! lol
I always asumed that medium was simply for 2 rings and large was for 3.
David

supersonic

Usually, but can't hurt to check! Mechs have a capacity stated in teeth. The capacity you require is calculated from what i said above.

David Lund

Thanks supersonic, i checked the XTR mech im looking at and it said fits 11-34 so i assume thats correct as my cassette is 11-34.
Cheers
David

supersonic

They also have a high and low cassette teeth rating which is not capacity - capacity is the abilty to take up chain slack in all gear combos.

The RD-M971-GS has a capcity of 33t
The RD-M971-SGS has a capacity of 43 teeth.

You would probably be ok with the former.

David Lund

Ah i see thanks very much!