Shimano XTR rear Mech question , advice needed

Hi , i've just purchased a M980 xtr rear mech ,

so i need to upgrade my cassette, now i'm wondering which type of cassette i need . or how i work it out.
not sure if :

11 - 32
11- 34
11- 36

?

All of the will work, it really depends on the ratios you want, which intern depends on how hilly your intended ride is and how tree trunk like your legs are.

...and what you are running up front, triple/double/single?

Im running a triple slx crank with a matching front mech,

if you go for an XTR Block, its only 11-34 or 11-36 in 10 Speed, I am running the 11-34 and it works like a dream.

If it's a long-cage mech, it has a 43T capacity.

43T means that the sum of the differences between smallest and largest cogs may be 43 teeth at most.

Sorry if that sounds confusing, I'll explain with an example.


If your crankset is a 24-32-42 tooth affair, that's 18T already (42 minus 24 = 18 )
If you have a 43T capacity mech, you need to take 43 and subtract 18.
So 43 - 18 = 25

Conclusion -> The difference between smallest and largest cogs on the rear must be 25 or less. In this case an 11-36 cassette would work.

Using a 41T setup (11-34 in my example) won't hurt, but with a 45T difference, the mech won't be able to handle the extreme ratios



You'll need to figure it out for your own bike, but once you get the hang of it, it's simple.

err , i've just tryed making sense of that after a few beers , i'd better read it again in the morning