Originally Posted by
SactoDoug
Here is a good summary that cites the actual law. If you want to read the actual wording of the law, just copy the cvc into findlaw.com.
http://www.bikelink.com/law_safety.htm
In other words, you can only be abreast if you are in the act of passing the other bicycle. Otherwise you must ride as close to the right edge as practical. Riding side by side without passing is not riding as close to the right edge as practical and is in violation of the law.
SactoDoug- So it sounds like you would take the position that it is fully permissible to ride two abreast in either of the following circumstances (because there is no obligation to right as far right as practicable):
1. if you are moving with the flow of traffic; or
2. if the lane is of a substandard width.