Thule “Big Mouth” Rooftop Bicycle Carrier $25 Looks like a set of bolt cutters. “Jaws” of bolt cutters goes around the “downtube” of bike. Tires rest in channel secured to top of Thule car rack. Wheels/tires are easily clamped to the channel. “Big Mouth” opens to slightly over 3” so it will handle large diameter downtubes. The jaws are clamped by a handle that is at the level of the car rack, so you do not have to climb on the roof to close the jaws. Complete with channel, clamps, end caps, and mounting hardware for rectangular Thule load bars. Two carriers available.