Gauthier, who rides for the Colavita/Sutter Home women’s cycling team, taped her race number onto her helmet early Sunday morning. She was there to train, she said, because the distance is longer and the terrain is rougher than any of her professional competitions.

She lined up with about 250 racers who rolled out from St. Francisville, about 30 miles north of Baton Rouge, La., under a foggy sky to test themselves on the back roads. Despite the ruts, few wanted to trade shocks or knobby tires for speed. Almost all rode lightweight road bikes, although at times, many pushed them.

The last stretch of gravel, through the Tunica Hills, tends to do this to people. The land here evolved over thousands of years, forced up as if by a lever by a subsiding Mississippi Delta, its steep grades carved by river tributaries slicing through silty soils.

Racers who were able to stay on their bikes spun slowly through these hills, dwarfed by hardwoods and tall moss-coated embankments veined with exposed tree roots. A man in a blue and white jersey threw his bike frame over his shoulder and plodded uphill.

“Bike racers suffer from this problem,” said Christophe Jammet, 25, an analyst for a hedge fund who came from New York to race. “They like to do things that cause them pain.”