Long or short cage derailleur?

ExplosivoUK

Hey, I have a Kona Scrap '06, it currently has a Shimano Alivio rear derailleur but doesn't select certain gears and skips a bit so I'm thinking of upgrading to an XT shadow. Only problem is I don't know whether I need short, medium or long cage. I'm running a single ring Truvativ Hussefelt crankset, and I don't know what the cassette is but apparently the bike has a Shimano CS-HG30 11-32 8 speed freewheel.
Anyone know which I need?
Thanks for any help
Jon :]

nicklouse

http://www.bikeradar.com/forum/viewforum.php?f=20020

read.

ExplosivoUK

Thanks, I've looked at the calculation but I can't work it out
My front ring have 38 teeth
Largest rear sprocket's 32
Smallest rear's 11
But unless I'm just being dumb that means the overall capacity has to be 59, and even the long cage XT shadow says it has a total capacity of 45T

supersonic

You need a capacity of:

32-11 = 21

dave_hill

ExplosivoUK wrote:

Thanks, I've looked at the calculation but I can't work it out

:shock:

ExplosivoUK

Oh, oh my lord that was dumb of me =P
Thanks for the help :]