Whenever I use my CycleOps magnetic trainer (like the one pictured below) my knees always end up hurting.
I don't have this problem when riding out on the road. My cadence is the same for the most part. I usually keep it on a medium resistance and the bike is level. The trainer itself rides really smooth and feels pretty similar to riding on flat ground.
Is there a reason why the trainer would cause pain in my knees?