FSA proudly proclaims that the bottom bracket in the FSA SL K Light EVO386 is the last evolution of the BB standard. Given the multiplicity of so called bottom bracket standards these days, this is a bold claim. It may have a point though, as the BB386 is really a series of adapters that plug into the most common versions of bottom brackets in order to accommodate the EVO386 cranks. Like its K Force relatives, the SL K's crank arms are molded around two tubular bladders, so the structure is buttressed up with a thin, central sheet of material that runs the length of the crank. The cross section resembles a peanut, and the result is a lightweight crank arm that doesn't skimp on power transfer. This power transfer is further complemented by the SL K's impossibly smooth and durable ceramic bearings. Ceramic can withstand even industrial applications without flinching, so for a bicycle, they're the bearing equivalent of spinning up on clouds. The wider, 86 millimeter spacing pushes the contact point with the pedals out slightly. Since the bottom bracket extends further, the crank arms don't have to bend as much to provide ankle clearance on the frame. That means less material, so it saves grams, and higher torsional stiffness because the crank arm itself is straighter. You know how bowed seat stays provide compliance to absorb road impact The same is true of bowed crank arms, but the extra compliance works against you by flexing, which hampers efficient power transfer. Given the flexibility of BB386, the SL K Light cranks are future proof. They'll travel with you from frame to frame, and by installing your choice of FSA chainrings designed to work with Shimano, SRAM, or Campagnolo drivetrain to drivetrain. No matter what changes you make to frame or groupset, you'll never be without the SLK Light's lightweight efficiency again.