On Saturday, the roads of west Marin and southern Sonoma counties were rife with those two-wheel vermin known as cyclists. Nearly 2500 of them. No, Critical Mass didn't make a drunken wrong turn on Friday night. This was an impressive gathering of the tribes known as the Marin Century.

Organized by the Marin Cyclists Road Club, the Marin Century is actually six different marked courses, including 50k, Metric Century, Mt. Tam Century, Marin Century, 200k Double Century, Mt. Tam Double Century options.

Always popular in the Bay Area, the profile for this year's event was even higher due to promotional commercials for it that appeared on Versus during its coverage of the Tour de France. In fact, by Wednesday, the Marin had already reached its rider limit of 2500 cyclists and online registration was closed. But Event Director Michael Sexton, showing his dedication to grass roots cycling rather than the almighty dollar, wisely held back some of the 2500 rider slots for walk-up same-day registration. Brilliant idea. More event organizers need to realize that they should never, ever, under any circumstances turn away somebody who has made the effort to physically show up to their event. Despite warnings to the contrary on the event website, nobody who wanted to ride was turned away from Saturday's fun because of event size restrictions.

The Marin Century is meticulously organized, but also forces the riders to accept responsibility, just as they would on their normal weekend rides. There are no signs or markers out on the courses. Riders receive a course map at check-in and must follow the turn-by-turn directions from start to finish. Neither are the courses roped off or protected from regular traffic, so cyclists must brave the dangers of automobilia, such as riding a rail along the edge of the pavement, with maybe an inch of shoulder to work with on a windy uphill while uptight and frustrated motorists stack up behind, honking and jockeying for their opportunity to roar past.

Under cover of darkness, the double centuries rolled off the start line at 5:00 AM, followed by the first groups of century riders at 6:30 AM. Event organizers instituted 10-minute interval starts this year to eliminate some of the crowding at the start, but even a small pack of bicyclists traveling in close formation at 5 mph and making all traffic stops will get tangled up. Group starts quickly weed out those with poor cycling etiquette and those who need work on their track stands and clip outs.

The temperature was a bit chill, but clear blue sky foretold of beautiful conditions for the day. Pockets of dense fog dotted the courses during the morning hours, creating some visibility issues out along the coast and in some of the low-lying areas. Especially treacherous was the technical descent down Marshall-Petaluma Road to Dillon Beach. It never really got hot-hot, but in the afternoon, on the exposed rolling hills of Novato and Petaluma, it got hot enough to make proper hydration critical. The redwood canopy coming back through Lucas Valley offered a cooling respite from the afternoon sun.

Also offering respite were a multitude of aid/feed/comfort stations strategically located along the courses. We say strategically because event organizers smartly placed the stations with increasing frequency (less distance between them) as riders progressed further along in the courses. And these weren't just a couple of card tables with some warm Gatorade, these were full-scale feed zones, with all manner of food and drink from Coke to Clif Bars, from to bananas to pasta salad -- they even had good, old-fashioned water. And lots and lots of everything.

Many event participants were locals who ride these routes as part of their regular training or recreational rides. What made Saturday's ride different was the opportunity for cyclists to ride with thousands of other like-minded folk. For cyclists, it was a glorious opportunity for the tribe to gather together, check out each other's bikes, revel in the mosaic of multicolored jerseys, and feel saftey in numbers out on the treacherous asphalt. Many of the courses shared routes, so a color-coded system of bracelets let riders know who else was riding their course.

From the long sightlines of Nicasio Valley to the painful pull up to Pan Toll Station could be seen the flash of jerseys, the glint of titanium and carbon fiber, and long lines of riders parallaxing up the side of the road and into the horizon. Everywhere one looked, riders were pulling off, pulling through, pulling ahead.

This is a "ride," not a race -- as many a pucker-faced weekend warrior will announce during the scrum that is the rolling start out of the Vallecito Elementary School parking into the streets of San Rafael -- there are no official results or podium presentations. While not a race, such a gathering afforded everybody the opportunity to learn something about their own fitness and ability by comparing themselves to other riders. In an event this large, there's always somebody to catch and somebody to hold off -- but no matter how fast or how strong you think you are, there's always somebody faster and/or stronger.

Mass quantities of riders also present plenty of opportunities for Tour style fun and games. Drafting, sprinting, cornering, pace lines -- this was a chance for the recreational cyclist to experience what competitive cycling is like, without the anxiety of actually competing. It looks mundane on TV, but not until you actually latch on to the wheel of a 10-rider train and feel the momentum and windblocking of the group pull you forward do you really get the concept of the peloton.

Speaking of pro cycling, SFist talked with many of the day's participants to see if the doping scandals of the this year's Tour de France had any effect on their interest in cycling or in the Marin Century. Some cyclists did admit to being a bit depressed about the professional manifestation of the sport they love, but to a person, everybody that we talked to said that what goes on at the pro level has no impact on their recreational riding. Are you listening cycling industry?