Do you guys do your interval training on a turbo trainer, or on the road? Most coaches / books seem to advise doing them on a trainer for consistency. I have no problems with 85-90% MHR intervals on the trainer (and keep them consistently within my targets HR zone) but I have a hard time getting my HR above 90% on the trainer. On the road I don't have this problem, even though perceived intensity is about the same. Any thoughts?