With the goal of satisfying sprinters, time trialists and track cyclists alike, Shimano has developed a hybrid version of its S-PHYRE RC903, relying on the extensive use of pressure mapping sensors and several prototypes before arriving at a final design.
However, unlike its S-PHYRE RC903 counterpart, the RC903 PWR forgoes a dual BOA retention system, a set-up that’s become de rigueur with most premium road shoes, in favor of a single BOA Li2 dial along with a velcro strap that’s designed to reduce foot movement, enhance power transmission and enable the use of clipless pedals with toe-straps, a popular choice among Olympic-level track racers.
“It’s that stable foothold with no heel lift or twisting that makes these the most efficient shoes Shimano has ever produced,” explains Shimano Lifestyle and Gear Product Manager Jessie Gascon. “They are engineered to help you go faster—period.”
“This shoe is for racers who can put out huge power numbers,” adds Gascon.
Elsewhere, to further ensure that no pedal output is wasted, the RC903 PWR’s “midsole-wrapping” is made from reinforced, breathable anti-stretch microfiber that’s 50% thicker than regular microfiber, creating a glove-like fit that ensures maximum pedaling stability and efficiency.
But, what’s truly unique about the new shoe’s 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. That combined with the midsole’s low stack height further stabilizes the foot, while the stiff carbon sole helps the RC903 PWR achieve a 12-out-of-12 rating on the Shimano stiffness scale for even greater power transfer efficiency.
Additionally, 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 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 that’s critical when winding up your sprint or driving to the finish of a tough time trial.
On top of it all, Shimano employed a new optical coating surface treatment that yields a dazzling color-shifting crystal finish on the outsole and heel of the RC903 PWR. Unfortunately, this treatment seems to have limited Shimano’s color palette to just white. So, gone are the groovy bubblegum blue and traditional black colorways – as if the peloton isn’t already awash with white cycling shoes.
So, how does the RC903 PWR perform?
For starters, the placement of the BOA dial is now attached to the main body of the shoe, making for far greater stability by anchoring the ankle much more securely than the standard RC903, which places the BOA dial on top of the shoe’s surround. Moreover, the closure system is further bolstered by zig-zag lacing that stabilizes the mid-foot via its own separate surround, while the velcro strap does do an effective job of securing the toebox area – something that will surely win plaudits for cyclists who hit the boards.
In sum, lightweight, ample ventilation and superb power transfer are accolades that foremost describe the new RC903 PWR, elevating the shoe into a new category of performance for Shimano, offering a level of comfort and stability that exceeds the RC903, a shoe that I previously gave a very favorable review, while rivaling the best of what the competition has to offer.
The new S-PHYRE RC903 PWR is available in sizes ranging from 40m to 48, with half sizes in 41, 42, 43, 44, 45 and 46 for $475.00.
Specs:
Shimano
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