Shimano designers first started down the path of creating a total performance lightweight cycling shoe with the original S-Phyre design. This second version of S-Phyre shoe, the SH-RC901, continues the evolution by with improved ventilation and new insoles. The S-Phyre follows Shimano's ethos of total integration with every component of the shoe designed with other in mind. This means the shoe was designed as a whole with the upper and sole being created at the same time for total fusion and synergy, resulting in top performance and comfort.

The shoe is based off the stiff, lightweight and surprisingly thin Dynalast carbon fiber sole. This refined sole design features anatomical curvature to serve up proper foot support. it has a unique toe lift position (called toe-spring) that increases leveraged power with less strain forward of the metatarsal zone. The seamless mid-sole construction process eliminates the board last, which reduces both weight and stack height. The sole also features active forward ventilation, a definitive graphic cleat set-up system, and 11mm more fore-aft of the cleat adjustment.

Attached to the Dynalast sole is the Teijin Avail synthetic upper. This magical Teijin material is incredibility supple and smoothly wraps around the curvature of your foot, while offering maximum support. The upper's sides are guided together in the Surround (no tongue) method for less seams and volume reduction. The back of the upper has a rather large one-piece molded external heel cup which does a good job of wrapping your heel and providing stability. The micro adjustable and dual independent Boa IP1 dial/wire closure delivers incredible fit and are strategically placed to asymmetric Powerzone wire anchor locations for performance optimization.