mixing 8/10 speed cassettes on trainer?
 

We just picked up an indoor trainer cheaply for my wife and I to use. I was thinking about getting a cheapo rear wheel and an old tire to use on it, but my question is what cassette to use? Her bike is an 8-speed rear, while mine is a 10. Would it be OK to split the difference and put a 9-speed cassette on the trainer wheel? Or just get a 10spd and worry about replacing her tires when necessary (they were stock to her bike, and she rides outdoors only rarely.)

Any advice appreciated- thanks.

If you're getting a special trainer wheel to be used in multiple bikes, you might as well just swap the cassette when you're making the wheel swap. It doesn't take that long.

I would just use the wheel and tyre that's on your wife's bike now, unless they are some really expensive tyres.

You'll want to match the cassette to the setup on your bike. If your bike is set up for 10 speeds, use a 10 speed cassette, etc. You'll probably find you are using only the middle few cogs, say 13-19, so you can pretty much use any cassette range -- I use (relatively) inexpensive steel cassettes for my trainer wheels.

Your answers were much as I had figured- thanks for the advice and clarification.