Originally Posted by
rollin
I don't / can't maintain high HR throughout the ride so I consider slight downhills as respite.
Is the most efficient approach to keep power constant?
Good question. I think the truth lies somewhere in between. In 20-40 minute TTs I sustain an average HR of over 170 (175 or so), which is very high relative to my max of about 185 (that's about 95% of max HR). So you probably can sustain a higher HR than you think you can. There are some longer downhill stretches in some of these TTs, and you do need to keep the hammer down.