In reply to DancingOnRock:
> As another poster pointed out, apparenty the cyclist knows best when the car driver should overtake. Frightening.
What's frightening about that? It is the cylist who will come off worst when a driver attempts to pass where it isn't safe. We know how close cars come to us when passing, and we know how they often cut in and brake sharply immediately after overtaking. We know that these are unsafe manoeuvres.
The really frightening thing is that
some drivers seem to think that it's safe to pass when it certainly isn't; when passing 'traffic calming islands' where the roadway is less than 2.4m wide; at the approach to any junction or roundabout (especially mini roundabouts); where there are cars parked at the side of narrow roads; where there is oncoming traffic; when the cyclist is stopped at a zebra crossing to allow pedestrians to cross; when there is no space in front of the cyclist. All of these situations result in the car encroaching into the safe gap around a cyclist, often requiring evasive action to avoid getting hit.
You may be surprised to learn that good cyclists have very good road sense; that's how they're still alive. We can see hazards ahead of us, and we can see where it will be safe for a car to pass us, and where it won't be safe. By adopting the primary position when it isn't safe, and dropping back to the secondary position when it is safe, we try to give clues to drivers to help them decide when to pass. We're not doing it to piss drivers off; we're doing it to try to stay alive.
The other thing about cyclists is that we're generally good at looking at the road ahead, and adjusting our speed to accommodate the gap to traffic; if we can see that there's an obstruction ahead, we'll slow down a little to allow time for the obstruction to clear. The last thing we want to do is come to a dead stop. The same technique is taught for Advanced Motorists and Police drivers. Sadly, many drivers seem to have trouble with this concept, and will advance into any gap, however small, before hitting the brakes. It's amazing how many times I'm coasting to an obstruction, only to have an impatient driver overtake into the gap, and then slam on the brakes (forcing me to brake too). What is the point of that; you're not going anywhere, and you're just wasting fuel and brake pads? Why not adopt a smooth driving style as used by Advanced motorists and Police drivers?
BTW, you do understand that cyclists can be car drivers too? So they also know about how to drive a car, and how to judge distances involving cars?