I'm not sure why you say that, RF. The vehicle code clearly states that we can:

> 257.660b Operation of bicycle upon highway or street; riding more than 2 abreast.
>
> Sec. 660b.
>
> Two or more individuals operating bicycles upon a highway or street shall not ride more than 2 abreast
> except upon a path or portion of the highway or street set aside for the use of bicycles.
>

I'd go further and say that this does not prohibit *passing* two riders that are abreast, only that it prohibits any more from staying in that configuration. Therefore, two more riders, dropping back, makes a max of 4 riders abreast at any given time, but since two of those are not *riding* alongside the others but being passed, it's allowed. I'm sure car drivers would not recognize the distinction, though; so it would be best to not rotate while cars are behind - even if an unoccupied 2nd lane exists.