Hi all, I have just bought a cheap rear wheel to use on a turbo trainer so I can switch back and forth between indoors and out. Current set up is an 8 speed 12-26 index, the wheel I have bought is a screw on and am struggling to find a cassette that matches. Is it more important to match the index or speed? I am near enough a beginner and have a beginner road bike, only plan on keeping it a year before upgrading, any help would be great!!