[Retric]

Rare as in what percentage of the time is someone on a bike going 45+ MPH?

I’d be surprised if it’s more than 1% for more than a handful of people. An ultra elite athlete on a normal bike can hit that on level ground in an absolute sprint, but you can’t sprint for very long. Going downhill requires time spent going up the hill.

The women’s 1 hour speed record is 30.6MPH, the men’s is 35.3 MPH. So sure downhill, rolling start, or motor-paced people can reach extreme speeds but they really aren’t doing so for hours a day. Streamlined recumbent bicycle can do it far more easily but that’s niche territory.