Odd. Most of the group rides I see here are the opposite in terms of speed. They are polite, and usually give you enough space to around if you are heading the other way. But, get stuck behind them and getting past is a nightmare. Most of the rides are on MTBs - I ride one myself but these guys cruise along at 24km/h and there are usually enough of them in the cycle lane to make getting past difficult. I like to ride at a little over 30km/h cruise and always get caught. I usually have to take to the traffic lane to get around. They are all kitted out with the nicest gear, really nice titanium bikes etc. There is surely the potential for a much higher pace but 95% of the groups I see just crawl along for (relatively) short distances 50 to 100km.

I much prefer to ride alone just because of the sheer number of bikes involved. I'm sure they are nice people and have similar goals to my own, but after a few (unintentional) riding in single file at slow speed experiences I'd rather ride my own pace. They also all start out late in the morning and take the entire day. This is a problem with a family of young kids. I need to get out before dawn, get my century in and get home within 6-7 hours maximum. Not going to happen in those group ride scenarios.