If the torpedo faced profile of Five Ten's Kestrel Clipless Shoes reminds you of a shark's nose, then you're being pointed in the right direction. With a combination of a durable upper and what Five Ten claims is its stiffest sole, the Kestrel certainly hits rock bench laden climbs and root lattices with all the voracity of an all mountain land shark. The enduro heart of the Kestrel is actually a spine: a carbon infused shank spanning the midfoot in the shoe's sole that serves as a conductor to direct power more efficiently into the pedals. More efficiency equals more speed equals more time to either line up another run or get the first choice of beverages from the cooler at the trailhead. The stiff spine is housed in an outsole comprising two different compounds. The first, Stealth C4, is hard enough for rock climbing. In fact, it was developed for rock climbing, but Five Ten imports it to the cycling world by ringing the Kestrel's cleat mount with the stuff. The same material that, according to Five Ten, rendered the world's hardest rock climbs climbable by dint of its unyielding strength shows up on the Kestrel to make sure there's no watt wasting outsole squish where rubber meets pedal. The other compound, Stealth Mi6, is a softer, tackier compound that dissipates impacts while navigating the lumpy ups and downs of enduro cycling and provides grip while scrambling across un rideable talus slopes and rock walls. The Kestrels are finished with a synthetic toe box mated to a mesh upper, with the former providing structure and protection while the latter keeps the heat down when the trail and temperature both go up. Gusseted stop gaps also bridge the distance between tongue and upper, so enterprising gravel and goat heads will find it that much harder to get in and get irritating. The whole thing is strapped down with a Boa IP1 wire buckle, something we're used to seeing on high end road shoes and more than happy to welcome to our off road wardrobe.