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.