I'm lucky enough to have built a second wheelset for my commuter over the Winter. Originally, my thought was to save the new/better set for Summer, and use the originals for salty Winter use with my studded tires. No need to swap tires, I thought originally...but then that cassette thing came up.

Do you folks change the cassette to the wheelset that's about to be installed, or do you have a cassette on each rear wheel?

Seems to me the chain and crankset would be worn to match the old cassette, and it would be the best option to use, but I've guessed wrong before! I've replaced the chain and cassette recently once, but still running the chain rings that have more mileage. If I bought a second cassette, now would be the time to do it, but I can't see the usage of the two cassettes working out evenly....howzit done, folks?

May as well go all the way to a complete second bike, no?

If I were going that route, I'd probably use a dedicated cassette and chain for each rear wheel.

Each wheelset has its own tires and cassette. Yes, they will wear at different rates, but it's really not that big of a deal. The cassette on my race wheels will probably last a couple seasons; the cassette on my training/commuting wheels needs replacing several times a year. I replace the chain once every two or three cassettes on the training/commuting wheels since those are the ones that receive the most wear. Chains are relatively inexpensive so you can error on that side of too often without spending too much or breaking anything.

You could be really precise and track mileage for each wheelset but that's too much like math for this old liberal arts major. When shifting gets crunchy or sloppy, I change the chain.

Say what??! Don't you have this back to front? A cassette will outlast 2 to 3 chains in my experience.

On this I fully agree. Chains are cheap (and you really only need to use the cheap ones). Replace often.

Yah, n+1, till you run out of money (or wives)...

I put a cassette and tires on the wheels that I swap. The reason for having swapable wheels is convenience which is much less convenient if you have to swap tires and cassettes each time you swap wheels.

My commuter is fixed, so I've got the same size cogs on both sets of wheels. I got the second set because I was breaking spokes on the OEM pair and just wanted a backup pair, but I do think of one set as the winter set and one set as the summer set just so I rotate them once in a while. And one set will take 37mm tires but the other won't, and 37mm won't fit under my fenders (which I remove in summer).

I could probably justify more frequent chain changing.

Sorry, you're right. I had that exactly backwards. 2 or 3 chains per cassette, whichever cassette wears faster.

I swap wheels, & don't worry about wear.

Each wheelset has its own cassette- they all work fine.

Might be better, like rotating chains to get longer life.