How to change a casette?

[Pedal Wench]

I just swapped out cassettes for the first time this weekend. If I'd known it was so easy, I would do it more often. Now that I've got the tools (gotta LOVE that chain whip!) I'll remove the cassettes to clean them too - much easier to clean them off the wheel.

[DebW]

On this particular bike, I have an XT dearilleur, longer chain, and 11-34. But, its not clear the chain will have too much slack when I move to the 12-27, since it seems to me that since 12 and 27 are both contained within my 11-34 casette, then the slack should be the same when in those gears. But, I'll see when I go to do it.

Your XT derailleur should wrap up the extra chain just fine. If you wanted the fastest and crispest possible shifts, you'd shorten the chain and the derailleur cage. However, since you want to swap between 12-27 and 11-34 cassettes, far easier to stick with your current chain and derailleur. Try it and see how you like the shifts.

[SadieKate]

I swap cassettes all the time. The bike that gets this treatment the most has the chain length set for a 32T cassette but I'll swap to a 25T when I want closer-spaced gearing. I use the same chain for both. Works just fine.

Bubba does the same with his cross bike, swapping a 30T for a 25T.

[Triskeliongirl]

Thanks for all the great advice! I went to my LBS to buy the tools, and the guy ended up changing it for me as he showed me how to do it, but it really did seem easy. I was glad he showed me though, cuz the tricky part was lining up the cogs correctly and it was just easier for him to show me than tell me. I put the wheel on, and it shifts smoothly without any derailleur adjustments. I think I'll take apart a really old wheel to practice on this weekend, to be sure I will remember what to do when I have to do it again.