After my bypass I was on Betablockers (Atenolol) and it affected my Bike riding. I could not get my HR above 130, and even at that low rate I was shatterred. I was taking it daily in the mornings so hit on a regime of taking one the night before a ride instead of in the morning. 9 weeks after the bypass I did a 40 miler on the road and it took in quite a few hills but kept HR to 140 and I was fine. On one of them I decided to go for it and got my HR up to 165, and then passed a roadie, so pushed harder to stay in front of him. Reached my Age Max of 172, and waited at the checkpoint at the top of the hill till my HR dropped to 120. Seemed to take ages but it did come down. Then over the next year I cut the Beta's until I was off them completely. No problems, and still get HR up to my current max of 165 somewhere on a ride, but cannot compete with the youngsters who have a max of 200ish