If a group start, keep with the group pace at the beginning. Slower or faster than the group leads to accidents. After a few miles most groups break up and spread out. Then you can ride in the gaps with more control.
Be aware of the other riders around you, especially on who is coming up from behind. A mirror helps.
Keep your line and stay straight as much as possible. Don't swerve sideways unless you have to and only if you know that it is clear behind you. If you need to swerve, signal or shout out.
Signal when you are stopping or slowing. Also signal road hazzards. Watch for signals from other riders.
Watch the road ahead. If a rider ahead of you goes down, they can take you and several other down with them. Look ahead of the rider ahead of you for upcoming hazzards.
Listen to what is going on around you.
Keep right unless passing. Don't block the left lane. If you are slower than the group pace, move to the right edge.
If you find that you can't handle the crowd, move to the side and wait until the crowd thins.
Group rides aren't bad. The biggest I've been in was 40,000 at Bike New York, but it thinned out quickly. The densest pack was at a 8000 rider Bike DC with several bottlenecks near the start.
Keep in mind that there is a wide range of experience levels on rides like this. Watch out for the other guy and ride defensively.
ps - being able to do a track stand or a very slow roll helps in a stopped crowd.
Last edited by cc_rider; 01-09-06 at 09:41 PM.