I ride on Sheridan Rd. all the time, and on a nice Saturday morning it's sometimes hard not to get caught up with a few other riders or a group. I frequently chit-chat with the other riders I end up with, and the vast majority of people don't mind if you sit on their wheel for a few minutes. Use your best judgement on how close to ride. You can usually tell pretty much immediately how squirrelly someone is. I've also noticed that people tend to pick up the pace when you catch them from behind, so I may sit on their wheel for a minute or two to catch my breath and let them settle down a little bit before I pass and say something friendly as I go by. If I get caught by a group, I'll ease up for a few minutes, let them go, and continue on solo. I have no interest in group rides, but if you do, there are plenty of groups on the Northshore of all levels of fitness for you to join.