Originally Posted by
cxwrench
First, the cassette is not a great place to save weight. Very little moment of inertia so the only time you'll notice it is when you lift your bike off the ground. Second, NOTHING will shift as well as a Shimano cassette and chain. This is especially true w/ the new 12 speed drivetrains.
Agree with this - OP, your shifting performance will only be degraded by a non-system cassette. For me, I would first consider laying out for the XTR cassette - but they are very expensive and hard to find, and the weight savings vs the cost is hard to justify. But you will save weight and shifting won't suffer. A possibility - and I am only spitballing here - if you race and are looking for the lightest bike on a particular day, get the Garbaruk and put it on for races, falling back to the XT when not racing. I would designate a separate chain for that setup, and you may also need a new driver body (not sure which it uses), so that would be part of the added cost - likely approaching XTR cost. Full disclosure: I have not done this, and have no idea how well it would work, but could be passable for a few hours after proper adjustment - the flipside to that though is that having a mechanical issue during a race is a big bummer. Wheels and tires is where I would look first though, if you haven't already done it.