Time Trial / Time Trialling / TT

Quite right too, HR is a poor proxy for all sorts of reasons. It can help inexperienced riders with pacing, but eventually you have to learn to ride on "perceived exertion" to get the last few percent on any given day. I doubt whether any top tester looks at the computer for anything other than reassurance during a race.

Riding a 24, watching the numbers gives you something else to put your mind to.