@Axtremus Have seen "bikes" on the Tucson bike trails that use a motion like an elliptical machine for propulsion. They passed me, which does not mean they are fast.

There are many miles of bike trails here. One trail goes over the pass to Vail. A company takes tourists to the top of the pass so they can zoom down. It is a nice climb.
The Katy trail in Missouri was started when I was a student. It draws people from around the world.