I let it all hang out on hills I am familiar with, but back off a lot on hills I am not. My max a few years ago was 59 mph on the back of a tandem,
a hill I have hit 50 with a singleton. Having the experience of going down at 38 mph due to a front flat on a curve 6-8 yrs ago, I am more
circumspect (and fragile) now. Since my neck is stiffer than it used to be a fully tucked position is no longer possible so I have a built in
airbrake that I used to not have. There are very few hills in my area that allow much over 45 mph, steep ones are too short, longer ones
too gentle.