Challenge's MTB One 650B Tubular is an amazing XC tire. It rolls fast and corners great, and is nice and light for effortless speed and super handling. But most of all, you'll love the awesome ride quality of this trick tubular. It boasts Challenge's supple 300tpi hand-made SuperPoly casing, with an anti-puncture strip under the grippy tread and polyester in the sidewalls for flat protection and excellent durability. Plus, it has a latex tube, which is thinner, lighter and more supple than ordinary butyl tubes, which adds even more pedaling ease, comfort and reduces your rolling resistance even more and also helps fight flats.