Riding in groups, whether on the street or in the dirt/sand, requires special attention and modified behavior. You not only need to look out for others in your group, but also for other groups or individuals.

While group riding on the street, motorcycles should ride in a staggered formation, with the lead motorcycle on the left side of the lane, the next on the right side, then the left and so on. This will increase the safety cushion between riders, allows everyone to see ahead, and prevents the risks of side by side riding.

Keep in mind that it's not illegal (in Ca) to ride side by side, (i.e. share lanes) with any other vehicle that fits safely in that lane with another vehicle. (This is the reasoning behind the fact that it is legal for motorcycles to split lanes, under certain circumstances and if done safely.) I often ride side by side, but only with riders I've ridden with for a long time. So far that includes only my wife and my brother. I don't trust anyone else.