California Motor Vehicle Code 21202
Operating a Bicycle on a Roadway
Vehicle Code 21202 is applicable to slow moving bicyclists and is similar in meaning to section 21654, which applies to slow moving cars and trucks. California Vehicle Code section 21202 states that bike riders must stay as close to the right side of the roadway as possible while riding in the same lane as cars. This law is intended to provide a safe and pleasant traveling experience for all persons using California roadways. This rule does have many safety exceptions, however.
First, if you can bike fast enough to keep up with the other vehicles, then you don't have to stay close to the right side of the road. For those bikers who cannot keep up with the flow of traffic, you must stick close to the side of the road unless there is an unsafe circumstance that prevents riding too close to the side.
Second, if the lane you are riding in is too narrow for a bicycle and a car to travel next to each other safely, then you should not ride too close to the side. Traveling too close to the side of the road will give the driver of the car the false sense that it is safe to pass you when it may not be. This could create a car accident that would cause serious injuries to the bicyclist.
Finally, you don't need to stay next to the curb if (1) you are preparing for a left hand turn, (2) you are passing other bikes, animals, or vehicles moving slower than you, (3) you are approaching a right hand turn, or (4) you are riding on a one-way street. If you are riding on a one-way road and there is more than one lane traveling in the same direction, you may also ride closer to the left hand curb if you so desire.
By following this traffic law, and considering safety to both yourself and others, the streets can be an enjoyable place for everyone using them.