The start of an off-road motorcycle or all-terrain vehicle endurance race is like a freight train rolling through an earthquake. Open courses stretch over grass tracks, woods and streams. Spectators are unfazed as, inches away, racers fly by. There’s a lot of dirt.

Dirt antagonizes the riders, too. But grit and stamina prevail, along with humor and kindness. Racers need pit crews, so families spread out to refuel riders. Local spectators, mud fleas, as they are affectionately called, gather at mud holes with drink-filled coolers and music, ready to pull machines out of the mud when they’re stuck.