stonecrd's experience seems to agree with my limited experience. I had a MHR over the winter on my trainer - it was the top end I could hit by standing on it and working until I thought I was going to fall off. When I got the bike out on the road I blew right through the limit and now find I spend most of my time at 85% of my new limit - I can stay there for an hour or more which is not consistent with what should be anarobic output. I must admit I am new to a HRM and I am really beginning to question the value on the road. Although I know it helped on the trainer.