I'm a year-round bicycle commuter. 8 miles round trip, about 90-percent on roadway shared with cars. By and large, the motorists are courteous and give me plenty of room to operate. For which I'm grateful.
I feel that the biggest threat to bike commuters are "loose cannon" cyclists. And there are two types. One is the uppity "lycra weenie" cyclists who seem to thumb their noses at traffic laws... swerving through traffic, ignoring signals, and in general behaving as if they are a superior life form. The other is the incompetents - those who shouldn't be on a bike. They are the ones who ride against traffic, ride totally unpredictably, swerve back and forth between sidewalk and roadway, etc.
Motorists see these antics and it gives cyclists in general a black eye. As a result, some motorists seem to resent sharing the pavement.
I've contacted my local police department on several occasions, asking them to step up enforcement, but they, too, seem to regard the lowly bicycle as a toy, and not worthy of their attention unless an accident is involved. A couple of times, angry physical confrontations have broken out between enraged motorists and cyclists (likely cyclists from one of the groups mentioned earlier, but who's to say?)
So... WHAT CAN BE DONE by responsible cyclists, to minimize the negative impact of the loose cannons?