Here's a great illustration of why it is not necessarily safe to ride on sidewalks

This accident occured yesterday between two bicycles, one was on a multi use trail and crossing the street (legally on the green) the other on the sidewalk and crossed his path perpendicularly.

[q] I was crossing with the green on the crosswalk going westbound to work, upon getting past the street another rider came down the west sidewalk going south, but she didn't stop, and there was a bus waiting on the southbound lane so she just "appeared"[/q]

This can of course happen with cars too! In fact the same intersection where this happend is kind of nasty as many cars do a right on red without stopping (illegal!) and seemingly without looking (stupid!), even though there is a very well known bike path that crosses the street there.

Even though it was at a slow speed (he said about 12mph) the cyclist who wrote about the accident broke the frame of his steel bike! and the other person involved had taco'd wheels and took a trip to the ER.

Never assume that sidewalks or bikepaths are automatically safe!