With Shimano's Dynalast technology and a hollow channeled, carbon reinforced composite outsole, the SH R107 Men's Shoes bring the power transferring stiffness, low weight, and general feel of pro level shoes to a price point that won't cost you one of the legs you'd like to attach them to. Dynalast is the big story here, as it's the same design featured in Shimano's flagship SH R321 model. It involves re shaping the footbed in order to limit the dead time of the pedal stroke. Shimano claims . 56% more efficiency on each pedal stroke a gain that adds up to figuratively save your legs over the course of a 40 mile group ride, 50 mile race, or a charity century.