Just got the Kickr, and in setting it up we have 3 bikes, wife's road bike and my new tri, both 11 spds, but for simplicity we would like to use her older Trek Edmonda on the trainer, as it somewhat "fits" both of us and we can swap our bikes in as we get closer to race days. Question is the Trek is a 9 spd, and won't work with current cassette(wants to jump, or climb gears as chain is thicker?). I searched forum and Googled it, answers vary from a simple spacer to changing cassettes is required. Anyone with first hand knowledge? And thanks!