After observing hundreds of bicyclists, myself included, the numbers say that bicyclists are either traveling at 10 mph or, when they get all cozy and comfy with each other out there in traffic, they slow down to 7 mph and shoot the breeze.
Once in a great while, a bicyclist may reach 35 mph going downhill with the wind, but 99 percent of the time they are not exceeding 10 mph.
As far as velocity times mass, when a drunk hits a bicyclist from behind at 50 mph " and the bicyclist is doing the average 10 mph " the cyclist is in serious trouble.
If a bicyclist is riding, facing traffic and against the curb " where they should be " then the cyclist has the opportunity to see the drunk coming and jump the curb to avoid being hit. The impact is zero mph.
We have been studying the "out of sight, out of mind" psychological effect of turning one's back to traffic. Just visualizing riding against traffic makes one very aware of the oncoming danger. Turning one's back to the traffic, so as not to see the traffic, gives some people the belief that the dangers no longer exist.
It is amazing that many people believe that if they don't see the cars coming they don't exist. Personally, it has the opposite effect on me. I imagine dozens of them coming at me.
Although motor vehicles are required by law to have two rearview mirrors for safety, the majority of bicyclists are against mounting rearview mirrors on their bicycles because, as we found out, that destroys the out-of-sight, out-of-mind illusion.
It isn't a matter of bicyclists against the world. We have the option of getting on a bicycle and traveling around in traffic. It's just that 95 percent of us feel the dangers outweigh the benefits.
Yes, it's a good cardiovascular workout, but so is off-road mountain biking and hiking, plus a thousand other things that cause much less stress.