Originally Posted by Helmet Head

I commute every day on a 45 mph 6 lane arterial with curbside parking on which motorists often drive 50-60 mph, while I'm doing 15ish in the center of the outside lane (if I ride just outside of the door zone, faster traffic is tempted to squeeze in next to me to my left). I watch faster traffic approach me from behind in my rear-view mirror. They see me and try to merge left, but sometimes cannot and are forced to slow down. My body language and lane position communicate quite clearly that this is the appropriate place for me to ride, and I'm not budging. They respect that. This is confirmed by drivers who know me and see me riding on their way to work (including my wife). I think most cyclists don't realize how normal it looks, and how acceptable it is, for a cyclist to ride this way.

Originally Posted by Ken Kifer

In looking at the specific problems of cycling, we see that the greatest problems are the volume and speed of the traffic:

1) On roads with little traffic, the speed limit is not important, although motorists approach more slowly on roads with lower speed limits. Therefore, these roads can be freely used by cyclists with only minor changes if any.

2) On roads with heavy traffic flow, cycling is impractical except for short distances unless the speeds are very low. Even if the cyclists have a separate lane, turning left is impossible and intersections are highly dangerous. Cyclists need alternatives to these roads.

3) On roads with average traffic:

a) Bicycles can travel in the automobile lanes when the speed of the traffic is about the same as bicycle speed, as occurs on crowded downtown streets or in residential neighborhoods. No change is needed.

b) When the speed of the traffic has increased to double the speed of the bicycle, then a widening of the lane by a couple of feet provides adequate room for motorists to pass when necessary. Motorists and cyclists need to be taught not to ignore each other, however, as doing so leads to accidents.

c) When the speed of the traffic reaches three times the speed of a bicycle, the room needs to increase to four foot. Again, the vehicle operators should not ignore each other.

d) When the speed of the traffic reaches four times the speed of the bicycle or more, the cyclist is in danger, even if given a wide or separate lane, due to the greater danger at intersections.

In summary, then, we need to provide alternatives only when the speed of the traffic is high (3d) and/or the volume of traffic is heavy (2). Unfortunately, the densely packed, high-speed road is on the increase, often leaving the cyclist no safe place to travel. A purist might insist that the cyclists continue to use the road anyway; others may want an independent bicycle path. I don't like either solution. Few cyclists are going to be willing to risk the busy roadway, and deaths might result. The bike path, on the other hand, is going to be taken over by joggers, dog walkers, roller bladers, and others, so that a practical cycling speed is impossible; in fact, bike paths have a much higher accident rate for cyclists than the road.