depends how you climb a hill........personally i sit and spin then stand the last 1/3 up over the peak.....i haven't used a stairmaster in years so i can't really tell you what muscles they're using....thighs and ass i would suspect so it wouldn't hurt.....but if you really want to train for hills....you'd be better off training on hills. i also suspect you'd do better training with intervals, sprints etc to get your power up.