With a little less carbon and a little more weight than its top-shelf brother, the Fury, the Mavic Chasm XC Race Shoe provides top-shelf performance without costing an arm and a leg. The Chasm dishes out all the thrills with a carbon fiber outsole, a synthetic microfiber upper, and Mavic"s ultralight and ultra-reliable Ergo-lite Ratchet closure, but leaves with enough cash left over to refuel at the pub.Mavic started with astretch-resistant micro fiber upper. Then it built in a thermo polyurethane (TPU) frame they call the Energy Frame Plus. This gives the shoe a bit more shape while keeping the upper soft and comfortable. You"ll see this wrapping the shoe from the arch on the inside to the ratchet on the outside. The large ratchet buckle is easy to use for fine adjustments, even with gloves on. The strap has deeper valleys between the teeth for better, more confident grip. The Ergo Strap Carbon runs through integrated, two-position nylon lace guides for both better fit and smoother action. The Chasm comes with an Energy Lock heel and an integrated, wrap-around Ergo Tongue for a secure fit, cool, breathable comfort, and freakishly light weight. The chasm uses a Ergo Fit 3D insole. Not only is the insole is three-dimensional, rather than two, but the three different density materials give some cushion on the top layer, a crushable bottom layer, and added shape from the heel cup through the arch. Mavic uses a uni-directional carbon fiber outsole for the Chasm. They still employ the Contagrip rubber, but have replaced the toe spike screws with short studs that sit flush with the rest of the sole and add a little toe grip in dry conditions. Mavic Fury Shoes are packaged with removable traction studs. The shoes come in both whole and half sizes from 4.5 to 12 UK. Claimed weight is 370g for a size 8.5.