En masse bicycle commuting The area I live (NE United States) doesn't have a very large infrastructure for biking. There are scattered bike paths and they've finally completed a bridge that allows me to commute to work, but there's nothing like these in London or this one in Denmark. In fact, most of the time I'm sharing roads with typical American drivers ("Ooh! Look! A bicyclist! Let's swerve into him! I won't even have to put the cel phone down!"). In general, I like the solitude and the fact that often I'm the fastest vehicle on congested city roads (nothing like zipping by a line of cars stuck behind a clueless driver) but I've started wondering lately what it's like riding with a lot higher volume of other cyclists on the road. In general I avoid the bike paths in the area on the weekends because there's a disproportionate number of folks who seem ignorant of riding etiquette (slower traffic keep to the right, don't let your children lurch blindly into the path of other cyclists, etc.) but these aren't regular commuters.

Folks who ride in areas with much better infrastructure (doesn't even have to be a bike "superhighway") - do you find that higher volumes of commuters mean a worst commute for you personally? Does having a larger commuter "culture" help with other riders or is it just as frustrating as being stuck behind them in a car as they apply lipstick and chat away on the cel phone?

EDIT: based on some discussion below, an additional (yet related) question - are there considerations built in to the larger bikeways to allow riders to keep a faster pace (i.e., multiple marked lanes)?
It all depends on the riders that you encounter, actually. I've been in group rides of 40+ where everyone was an experienced cyclist, and it was smooth sailing. People were able to move in and out of various parts of the group at will, road safety and laws were observed, etc.

I've also been in rides with 6 people where the handling was sketchy, they spread out across the road, ignored traffic laws and it was generally not a pleasant experience.

The "commuter culture" is pretty much going to be just like the car commuters. You'll have quite a few that obey the laws and operate in a safe manner, then you're going to have the few that ignore the laws, people around them, and generally make it unsafe for everyone else. My favorite lately was a college "hipster fixie" rider that was riding no handed, cigarette in the right hand, cell phone glued to the ear with the left.

Operate your bike in a safe manner, watch out for the cars and the unsafe riders, and you should generally have a pleasant commute (And yes, there is nothing better than zipping past a long line of stopped cars! :D )