Lots of spandex and skinny tires passed through town earlier this week, as the USA Pro Challenge rolled through Aspen on its seven-stage tour of Colorado. Nicknamed "America's Race," the road-biking event features more than 100 professional cyclists on a grueling race through some of the state's toughest terrain. Coming into Aspen from Copper Mountain for Stage 3, riders climbed and descended 12,095-foot Independence Pass. On Thursday, they grunted back out of town toward Breckenridge. 

Today, they have a time trial in Breckenridge before heading to Fort Collins for a race to Loveland and then a final culminating stage from Golden to downtown Denver. In its fifth year, the return to Independence Pass was an exciting shift for Colorado residents. The iconic climb is one of the "queen" stages and the highest point in the race. 

Up top the pass on Wednesday, about 1,000 spectators gathered to cheer on riders as they reached the crest. Hundreds biked up there from both the Leadville and Aspen sides on Highway 82, braving the chilly temps and strong winds to show their support for the cyclists who had ridden much further than them. Coming into Denver on Sunday, the same competitors can expect to whiz by hundreds of thousands, having been seen by more than 1 million in their cycling sweep of the state.