The Challenge Gravel Grinder is designed for gravel-specific 'cross racing or riding. Featuring a center file tread paired with raised side knobs for low rolling resistance on straights confident traction while cornering. With unpredictable terrain in mind, Challenge also reinforces the nylon casing on the Gravel Grinder with its Double Puncture Protection System (PPS2) to get you through your rides and races without losing time changing flats. This clincher model was designed to be the best option for cyclists racing on aggressive terrain. The Gravel Grinder fits on most rims measuring between 17 and 23mm wide (though its healthy girth recommends it most on the wide end of that spectrum), and weighs in at a claimed 375g.