Flobots' "Handlebars" is one of the most unlikely hits in recent years. The tune morphs from a gentle acoustic rap-along about human ingenuity into a turbulent, distortion-tinged testament to the destructive power that mankind now wields. The song's swift takeover of modern-rock radio has resulted in newfound acclaim and demand for the Colorado band, which will be one of the main acts at Seattle's Bumbershoot music festival later this year. Tonight, Flobots warm up for the big gig and make some new fans in South Florida. Backpack-rap maven Busdriver lends support.