I was in a Canadian school zone today and thought that the posted speed, 40 km/h, should simply be referred to as "fast." It's 1.6× the speed of a four-munute mile and 10× walking speed. It's fast.

Stroads would be fast-and-a-half.

Intercity highways, ie. "back roads," would be double-fast.

Expressways, 2.5 fast. Triple-fast and beyond is certainly too fast.

The point is: anything that is fast is doable on a bike. Faster than that should be on rails or have a professional, full-time operator — not anyone who can pass an eye exam, and hold a No.2 pencil or click a mouse 40 times.

Fast is fast enough. If you need to go fast, go alone. If you need to go far, or faster than fast, go together.