The 31- and 33-mile nordic-ski marathons at the Birkie are the largest in the U.S., with 5,000-plus entrants snaking through thick pine forests from Cable to a tent city in Hayward, where finishers are rewarded with local beer and brats. Although racers set off in ten waves, based on prequalifying times, the start is still no picnic.

FORUM: RACE SMACKDOWN

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The waves go five minutes apart, so be at the adjacent warming tent an hour early to get a good position. "Give yourself space," says 25-time competitor Marcia Engebretson. "Crashes occur, poles are broken—be sure to wear eye shields." Start slow: The highest elevation, about 1,700 feet, is in the first third of the course. Near the end, the wind can be blasting on the mile-long section across Lake Hayward. Draft off of someone if you can. From $70; birkie.com

GO FOR GOLD
GT wants to give you a mountain bike. And a pit crew. And cheerleaders. All you have to do is be the highest-placed amateur at one of the seven events in the Golden Bike Series, which begins with April's Sea Otter Classic. Your reward: Either a GT Zaskar hardtail or Marathon full-suspension bike—in a one-off gold—plus mechanics, eight cheerleaders, and both your entry fee and round-trip airfare for two to the next race. Win again and the good times continue; lose and it will all be taken away from you at the finish line and given to the victor—your old bike now the pumpkin in your Cinderella story. (Don't worry. At year's end, all winners receive a bike to keep.) gtisgolden.com