Whether sprinting for a WorldTour win, racing on the track, or going for your best time trial finish of the season, just fractions of a second can make all the difference. Mere millimeters can separate winners from the rest of the field. Wasted watts become wasted opportunities.
It’s these razor-thin marginsโand the unrelenting need for optimal power transferโthat drove the development of Shimanoโs new S-PHYRERC903 PWRย road cycling shoes. The same shoes that will adorn the feet of some of the worldโs fastest riders this summer at the biggest races of the season.
Designed for powerful track racers, speedy sprinters, and pure time trial specialists, the S-PHYREย RC903 PWRย (as in power) utilize a host of unique features to assure you get maximum forward propulsion out of every pedal stroke. Taking initial cues from the S-PHYRE RC9T track cycling shoe, theย RC903 PWRย provides what Shimano Lifestyle and Gear Product Manager Jessie Gascon calls โthe feeling that your foot is in a pillow thatโs in a vice.โ
Indeed, theย RC903 PWRย delivers superb all-day ride comfort while assuring that your foot is completely secure without any unwanted fore-aft or up-down movement. โItโs that stable foothold with no heel lift or twisting that makes these the most efficient shoes Shimano has ever produced,โ explains Gascon. โThey are engineered to help you go fasterโperiod.โ
To reach this pinnacle of efficient energy transfer Shimanoโs design team utilized pressure mapping sensors to determine how various racers applied pedaling force during their pedal stroke. The resulting data revealed three core rider types with three very different cycling footwear performance needs.
There were the lightweight climber types who generate most of their force on the downstroke. There were the fast twitch sprinters who create power almost all the way around their pedal stroke. And there were riders somewhere in between, who were usually all-arounder types.
With this information in hand, Shimano shoe designers constructed three different shoe upper structures to meet the unique and specific needs of each rider type. One features extra mesh to help keep weight low and enhance cooling (for the climbers). Another has a more traditional balanced design (for the generalists). And oneโfound on the new S-PHYREย RC903 PWRโutilizes a 360-degree surround wrapping upper that delivers the enhanced rigidity and stability required by the sportโs most powerful sprinters, track racers, and time trialists.
โThis shoe,โ says Gascon, โis for racers who can put out huge power numbers.โ
To ensure none of that output is wasted, the S-PHYREย RC903 PWRโsย midsole-wrapping upper is made from reinforced and breathable anti-stretch microfiber thatโs 50% thicker than regular microfiber. Thatโs combined with a traditional padded tongue that together provides a comfortable and cool glove-like fit for maximum pedaling stability and efficiency.
But whatโs truly unique about the new shoeโs upper, says Gascon, is its embedded thin, pliable plastic reinforcement layer that helps maintain comfort while also delivering the rigidity racers need to generate force throughout their pedal stroke. Thatโs combined with the midsoleโs low stack height that further stabilizes the foot, and a stiff carbon sole that helps the S-PHYREย RC903 PWRย achieve a 12-out-of-12 rating on the Shimano stiffness scale for even greater power transfer efficiency.
Shimano shoe designers also increased heel cup stiffness, which prevents unwanted twisting and assures optimally secure foot positioning during intense accelerations and sustained high cadence efforts. Foot security is further bolstered by a robust BOA Li2 metal dial closure mechanism with power boost guide cable routing. This provides perfectly even tension across the top and middle of the foot, plus increased cable leverage so riders can achieve the truly cinched-down fit thatโs critical when winding up your sprint or driving to the finish of a tough time trial.
Below the S-PHYREย RC903 PWRโsย single BOA dial is a Velcro strap that reduces foot movement, enhancing power transmission and enabling the use of clipless pedals with toe-straps, a popular choice among Olympic-level track racers.
To top it all off, Shimano employed a new optical coating surface treatment that yields a dazzling color-shifting crystal finish on the outsole and heel of the S-PHYREย RC903 PWR. Itโs the perfect finishing touch for a shoe thatโs sure to be at the front of races across the globe in 2024.
Efficient Power Transfer
Reinforced surround wrapping upper with tongue delivers glove-like fit for enhanced rigidity and stability, while the stiff carbon sole and low stack height midsole promote maximum pedaling efficiency for optimal power transmission.


Ultimate Foot Security
Heel cup with anti-twist stabilization enhances foot hold during intense accelerations and sustained high-cadence efforts, while BOA Li2 dial with power boost cable guide provides perfectly even closure tension for secure and comfortable pedaling performance.
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