Seems to me that lately the commuting hazards have not been vehicles but rather other cyclists...

For example, this morning:
1. young woman on bike, no helmet, earbuds, goes flying past me as I'm stopped at a stop sign, I pass her once through the stop, she zips past me at the next stop sign, then I catch up to her zipping in and out of a lane that is blocked because a part of the road is under construction;
2. guy on bike, no helmet, comes flying out from a side street, crossing the (fairly busy) road RIGHT IN FRONT OF ME! Did not stop at stop sign, did not see me. Fortunately, I was able to brake & swerve to avoid crashing into him. Guy seemingly oblivious - I admit, though, I did yell at him.

Sheesh!!