THE ONLY ROUTE through the Carrizo Gorge, a 1,000-foot-deep rift in California's Anza-Borrego Desert, is an 11-mile stretch of abandoned track that ducks into 17 tunnels and crosses 13 bridges, including the 180-foot-high Goat Canyon Trestle. It's an ideal venue for railbikes (bikes tricked out to ride the rails with awning pipe, hose clamps, and skateboard and shopping cart wheels), mainly because it's just about the only venue. Almost all of the nation's thousands of miles of decommissioned track are still privately owned—and off limits to railbikers, who stay off active rail for lethally obvious reasons. Enter Carrizo Gorge Railway vice-president Gary Sweetwood. He sees opening the otherwise-inaccessible gorge to railbikes as a way to foster the growth of the sport and get outdoor enthusiasts interested in his company's struggle to restore the line. So, on one hot weekend in May, he invited 15 railbikers to spend three days pedaling their rigs on the rusting iron. "This is in the raw right here," says Sweetwood. "These people, they're the first of their breed."