One reason I seldom participate in the many charity rides that are currently popular is because I don't trust riding so close to some stranger, especially the sort of weekend warriors who go on these things in hope of getting their picture in the news.
Group riding is best left to established, well organised clubs who strictly follow a set of well defined rules.
Here is a typical rule set:
1. The road captain will research the route for every planned club ride, planning stops based on the bike with the shortest range and the physical needs of all the members.
2. The formation is, road captain at the front left. Prospective and new members near the front, as it is easier to avoid someone who gets stupid than to get out of their way. The best mechanics ride at the rear to stop and help anyone who has to drop out.
3. The formation should be staggered with enough spacing to be able to avoid a chain reaction pileup, but close enough that idiot cagers won't break in. Side-by-side riding is for parades and such, not fun rides.
4. There should be an established set of signals that everyone understands. Signals should be passed along the ranks to make sure everyone sees them. Radio intercoms should not be used, one broken radio could cause a disaster.
5. Everyone should be briefed on the route in case they are separated for some reason. The ride pace should be slow enough to allow separated members to safely catch upp.
6. Lane changes for the purpose of passing slower traffic should originate with the road captain. After passing, the pace should be adjusted to allow the rest to pass safely and fall back in line. The road captain should make sure everyone is back in line before picking up the pace.
7. Lane changes for the purpose of turning onto another roadway should start at the rear of the group. This is so that the rest have a clear lane to move into.
