The long ride over the weekend and the prospect of longer rides two days in a row in just two-and-a-half weeks has been making me think more about distance lately.

We’ll do 100 miles the first day of the MS 150, and 77 the second day. That’s a lot of riding. But for some folks, those are just walks in the park.

I’m talking about randonneurs.

Randonneuring is marathon cycling. But not only do you have to complete long distances, you have to complete them within a certain time frame. In that way, it resembles an auto rally more than a race.

Randonneurs will go 200, 300, 400, 600 or 1200 kilometers in one ride. For the metrically-challenged, 200k is 125 miles, more or less. I’ve done 100 miles once, and thought that was as far as I’d ever care to go. That’s the kind of ride randonneurs stage to introduce new riders t0 their sport.

At first blush, randonneurs don’t look much different from the typical club ride. They’ve got bikes, and helmets, and lycra jerseys, and spandex. But upon closer inspection, there are some notable differences.

Randonnees, the rides put on by randonneurs, are unsupported. So each rider has to carry food and drink, and enough in the way of tools to make roadside repairs if the bike breaks during the ride. The rides start before the sun rises, and keep going after the sun sets. So the bikes are equipped with head and tail lights. If it’s really long, arrangements might be made for rooms at motels along the route, and riders take turns flopping on the beds for only two or three hours of sleep.

As the day warms up, riders will likely shed some layers of clothing, so they often use large saddle bags or rack-mounted bags to carry their extra stuff. Many carry smaller items, such as energy bars, a cell phone, a camera, and tire repair kits, in a handle bar bag. Because they ride rain or shine, randonneuring bikes are usually equipped with fenders, and perhaps somewhat wider tires than most club riders. And because it’s important to stay comfortable after being in the saddle for 12 hours on end, many randonneurs use the old-fashioned Brooks leather saddles, sometimes even sprung versions.

The bikes themselves are a little different, too. Speed is not the aim, although some are fairly speedy. Durability is of paramount importance, because of the lack of sag support. And to add to comfort, a certain style of frame is sought after.

The resulting bike looks like a throwback to earlier cycling times. But if form does indeed follow function, the randonneuring bike is a highly functional machine. Most often, it has a steel frame. It has drop bars, but they’re often mated to a threaded headset, and the bars are up at saddle height.

During a ride, cyclists have to check in at “controls” to have their brevet (bruh-VAY) cards stamped and signed. Sometimes, ride organizers slip in a “secret” control, to assure that riders don’t try to shorten the course. Failure to reach a control results in disqualification.

If you’re interested in randonneuring, you might start by checking out Randonneurs USA, the governing body of randonneuring in the United States. Their web site will point you to rides and to area clubs.

If you really get the bug, and want to do the big daddy, it’s the Paris-Brest-Paris (PBP) ride in France, run every four years. Next year, 2011, is one of those years. You have to qualify to ride PBP, and you do that by completing brevets of 200, 300, 400, and 600 kilometers during 2011. A brevet is a ride for which you are certified to have finished, and the record of your finishing goes to Paris. Even that might not be enough, though. Because of the popularity of the ride, each country is assigned a quota of riders, and once it’s filled, it’s filled.

For me, the allure of randonneuring is in the thought of covering so much ground on a single ride. But thinking about it and doing it are two different things. Talk to me after the MS 150 and we’ll see if I’m up for something longer.