Correct me if I'm wrong, but I think that you really can't have a society without some sort of law enforcement.
I say this because no matter how perfect a society is, the people will always designate certain actions as criminal, as a way of providing a standard of actions. Think about the Amish: they exist in a society without crime as we know it, so they designate acts like building a barn in an unconventional way as a serious offense.
Here's my point: A community bike ride is by nature much safer and less disruptive than your average motorized rush-hour. Butlaw-enforcement will still invent problems with it, as a way to keep you under their control. The unfortunate fact is that when you use a more perfect mode of transportation, you'll be held to surprisingly more strict standards of behavior, even when they're unreasonable.
That's just the nature of deviance in our society, and the only way around it is to fly under the radar. Unfortunately, that makes it pretty much impossible to get through a community / CM style ride without being harassed by the police, because the very nature of their role in society relative to yours dictates that they find something wrong with you.