Armstrong, riding for Team Radio Shack, got caught in a crash at the head of the peloton involving fifteen or twenty riders shortly after the start of Stage Five.
Armstrong remounted, but the bleeding and swelling from the cut under his left eye became serious, and he pulled aside and entered the team car at the 13-mile mark.
Several other Radio Shack riders were involved in the crash, including José Luis Rubiera, Levi Leipheimer, and Jason McCartney. Bissell’s Ben Jacques-Maynes and Daniel Holloway went down, as did Saxo Bank’s Stuart O’Grady, Fly V’s Jay Thomson, Cervélo’s Heinrich Haussler, and HTC-Columbia’s Bernhard Eisel. 
O’Grady, Hasussler, Thomson, and Holloway also withdrew after the accident.
Stage 5
The stage ended with two laps of downtown Bakersfield, with the 10 percent China Grade climb at the start of each lap. The climb slowed the true sprinters, allowing the General Classification leaders to battle head-to-head for the stage win.
Garmin-Transition's David Zabriskie made his move too early, and faded 100 meters short of the line. HTC-Columbia's Michael Rodgers passed Zabriskie, but 20-year-old Liquigas rider Peter Sagan surprised the veterans with sudden burst of speed, taking the win by two lengths.
Zabriskie and Rodgers ended up with identical overall times, but Rodgers was awarded the yellow jersey based on better prior results. Levi Leipheimer finished the stage in seventh, maintaining his third place overall, 10 seconds behind the leaders.
Peter Sagan remains in fourth overall, 21 seconds back.
Friday's stage is 135 miles of hard climbs with a mountaintop finish at Big Bear Lake. This will be the first true test of endurance. Expect a lot of gaps to open in the General Classification, and a lot of riders to fall off the back tomorrow.
