Just did our local century a couple of weeks ago. 2000 registered. It was not a mass start, but everyone seems to go at a similar time. Ran into much traffic. Had a few people blocking the whole road, and not having the acceleration as I do on my single, we had to pick and choose when to go. No one wanted to work together either. They were all happy to jump on our wheel on the flat runs, but then didn't want to let us draft and catch a break. Very frustrating. There were a few tandems on the ride this year, and we ended up hooking up with one team for the last half of the ride. 2 of the other teams were just way to fast for us. Ran into a lot of traffic again this week at the start of the local club ride. Just some real ignorant riders blocking the whole road, and/or never checking their mirrors to see who was around them. We call out when we are overtaking, but some just don't care.