CYCLISTS in the 2011 Tour of California are up against what race analysts are calling the most difficult tour yet—and it’s because of the hills.

This year’s tour—the sixth rendition of one of the world’s youngest yet most acclaimed stage races—features more climbing than in years past, plus an unprecedented element of competition: two mountaintop finishes.

Wednesday’s Stage 4, an 82-mile run beginning in Livermore, finishes at the summit of Sierra Road after a 1,700-foot ascent. On such grades, climbers emerge from their respective pelotons to showcase their strength.

Unlike the compact and muscular sprinters, climbers are lean athletes of slight build and tremendous lung capacity. Some of the most acclaimed cyclists in the game have been climbers. Greg LeMond and Lance Armstrong were two of the most gifted climbers of their respective eras. Current star Levi Leipheimer of Team RadioShack, now 37, is also a climber, as are Samuel Sanchez of Team Euskaltel-Euskadi, Serguei Ivanov of Katusha Team and Jesus Hernandez of Saxo Bank Sungard.

Local cycling coach Matt McNamara, of the Sterling Sports Group in Sunnyvale, notes that Stage 4 features one of the biggest climbs in the race—the 1,900-foot ascent up Mt. Hamilton—relatively early in the stage, finishing at mile-55. For most of a race, climbers—as well as sprinters and other key riders—pedal behind the protection of their teammates, who ride in a peloton formation that provides protection from headwinds.

“As soon as a climber puts his nose into the wind, he’s saying, ‘I’m going for it,’ and they have to be confident that they have enough steam to last and stay ahead on their own all the way,” McNamara says. He doubts that any climbers will be bold enough to break away from their pelotons until the final miles, when Sierra Road rises to meet them.

2011’s Amgen Tour of California was scheduled to begin on Sunday amid the peaks and passes of the Lake Tahoe basin but was cancelled by wind, rain and snow. The second stage led the race’s 18 teams to Sacramento. Stage 3 ran a relatively flat course from Auburn to Modesto—a playground for the Tour’s sprinters.

Though Stage 4, which begins Wednesday at 11:45am, bodes to be a thrilling one, McNamara guesses that the teams will collectively “save their matches” for later stages. On Thursday, for instance, the cyclists are facing 139 miles. And Stage 7, the second to last, will subject them to perhaps the most pain of all with two huge climbs, including a dramatic finish at the summit of Mt. Baldy in San Bernardino County.