Scared by the idea of a 24-hour race?
Get a grip. It's a relay, man. Only a handful of diehard soloists go round the clock alone. If you're on a five-man team and your team averages 90-minute laps, like most people, you'll ride four times, max. So you don't need to train 20 hours a week for a year straight. Still, good planning, fitness, choice of partners, equipment and food will go a long way.
How much to train depends on your goal. Just want to finish? Better be at least a beginner-level mountain biker with a couple all-day expeditions under your belt. Even if you're on a molasses-slow, 10-man corporate team, you'd better be able to handle technical trails, single-track and fast descents. Beginner riders might spend two hours or more on a lap.
Want to compete? Better hammer for months. Otherwise, your speeds will radically drop off as fatigue sets in. Generally, train with an eye on the amount of time you may be in the saddle on race day. Those on five-man teams—a popular category that often has coed and all-women squads—might ride four to five hours total.
Riders on high-performance, four-man teams often turn sub-hour laps, six times each. Two-person teammates usually do a total of 12 hard hours, usually broken into two laps at once so their partners can rest and eat. Top solo riders usually don't sleep and try to make brief food and equipment stops.
You and your bros better be compatible: ability-wise, goal-wise, attitude-wise. After all, you're stuck together for a whole weekend. If you want to push hard and Izzy only wants another nap, tensions will flare. It'd help if you had a mechanic along, too. If none of you can fix a flat or remembered to bring chain lube, big trouble.
Also, pick the right category to compete in. The 24 Hours of Adrenalin series offers two-person, four-person, five-person and corporate (six to 10 people per team) categories in all-male, all-female and mixed variations. If you can't stomach a partner, try the solo category, which is limited to 30 riders.
Don't be a couple bulbs short. Unless you've been locked in a cave since birth, it's no secret that about half of the 24 hours will be in darkness. Bring well-charged 6-watt-minimum lights and know how to use them. Don't make the race your first night ride.
In addition, arrive early enough to pre-ride the course in daytime, so you'll be aware of major obstacles that night. There are two possible lighting set-ups: handlebar-mounted and helmet-mounted. Better riders use both.