These races take place at a single venue with racers making multiple laps around a carefully laid out course. The schedule usually runs from noon to noon, with racers continueing to make laps over the nighttime hours.
Now, before you get too excited, some people do race these 24 hour mountain bike races alone (Solo), but most people race in a team. Racing in a team requires you to send out a single rider at a time to ride a lap on their own.
Depending on the race rules, teams are usually made up of 4 or 5 members with each member running multiple laps in whatever schedule they choose to run. Some races allow much larger teams allowing most of the team members to only race a single lap.
The only significant new equipment required for 24 hour mountain bike racing is a good light system for the nighttime laps. These aren't cheap but well worth the money if you plan to get into 24 hour races.
A 24 hour mountain bike race can not only be a lot of fun, but it can be a mountain bike cultural experience. Seriously, these races are worth doing even if you have no intention of trying to win.
With hundreds team members sitting around waiting for their turn to ride, there are plenty of good times to be had in and around the venue. There's nothing like hundreds of mountain bikers with lots of time to spare to create some good old fashioned mountain bike mayhem.