57 and max HR I can hit is 155.

That only happened once that I am aware of. I don't know how you guys get up into the ranges shown here. I'd pass out long before I got there for sure. On the hills I ride regularly I max out at about 150 and have to cut back at that point. Nothing wrong with my heart just am pooped at that point.

I'll keep working on the engine but I have no worry about ever hitting the ranges of you heavy hitters out there.