I disagree in the strongest possible terms. I have seen numerous accidents caused by speed on a multi-use trail.

To assume that everyone knows -- or should know -- what "on your left" means is unrealistic. What if they are hard of hearing or don't speak English? What if they haven't used a trail like that before? What if they are six years old and using training wheels?

Twenty mph in an area that's even slightly crowded is way too fast.