Test Shimano S-Phyre RC-903 shoes

For the fourth version of its high-end S-Phyre shoes (after the RC-9 released in 2017, the RC-901 in 2019 and RC-902 in 2021), Shimano seems to have definitively solved the yeartagUsual mismatch between performance and comfort on the new RC-903s, thanks to an upper and tightening dynamics that promote firm support but without creating the slightest pressure point. Shoes appreciated by pros as well as amateurs or fans of long-distance outings.

By Guillaume Judas – Photos: @3Bikes.fr

The S-Phyre RC-903 retains the features that made the first models successful, namely a very rigid outsole directly linked to the upper and its enveloping fit, an insole with adjustable arch support, a low arch and a thin heel with an anti-torsion shell to limit unwanted foot movements when pedaling. On this new model, already used by pros like Mathieu van der Poel from the 2022 season, Shimano has mainly reworked the interweaving of the layers of microfiber leather in the upper part, for an even softer and more progressive tightening than on previous models. This same coating also seems slightly more flexible to us (without being stretchable when tightened) than the previous version RC-902, and significantly less steep than 901 RC-2019s.

Shoes that are truly different from the competition

One of the main specificities of the S-Phyre concerns the type of assembly of the shoes, with the absence of a midsole normally devoted to fixing the upper between the outsole (carbon) and the comfort insole. The upper is directly fixed under the carbon sole, which allows both sides of the shoe to gradually close on the foot at the same time when tightening, and to gain a few small millimeters of height between the foot and the outsole, for theoretical additional stability of the foot on the pedal.

On the S-Phyre, we also find a very rigid sole (index of 12/12 on the Shimano scale), fairly low camber and relatively wide at the cleat location, for a large adjustment range with less risk of overhang when placing the cleats, also facilitated by numerous markings. If you opt for this model coming from another pair of shoes, it is likely that you will have to lower the saddle by a few millimeters to find your marks.

The S-Phyre also retains the insole with adjustable arch support, with the choice between two thicknesses of pads (provided with the shoes), which allows you to support the midfoot and provide evenly distributed support throughout the shoe. Note however that we would have liked a thickness of more, for a more important support if necessary. Indeed, the "high" support (the red one) corresponds more or less to the blue sole sold after-sales at Speclialized (the intermediary), and in our opinion it lacks an additional level for the very marked arches of the foot. Nevertheless, the effort of the brand to provide a customization of the supports is already commendable compared to other brands.

The S-Phyre RC-903 retains the two Boa Li2 dials for tightening, with a low thickness and tightening/loosening notch by notch. At the instep, the dial is placed on the main flap of the shoe, unlike most shoes on the market. This theoretically allowsimprove foot wrapping, as the two Boa tighteners pull the wires in opposite directions. The Boa Li2 are precise and powerful, but less so than the Boa S3 found on Specialized shoes for example. On the other hand, they allow the tightening to be completely released by a simple pull, which is not the case with the S3.

One of the main differences with the first three generations of S-Phyre concerns the Boa tightening wire on the forefoot, which now runs directly through the fabric rather than following plastic guides. This has the effect of lightening the shoe, reducing the risk of feeling hard points when tightening, and better distributing the pressure. Unlike the RC-902, we can distinguish a mesh part on the front, designed to improve the superposition of layers when wrapping the foot and tightening. Shimano has sought to stiffen the rear part of the shoe, particularly at the instep and heel, but at the same time using more flexible and elastic materials and design on the forefoot to optimize comfort. The heel is particularly thin and tightly encloses the entire rear part of the foot, thus preventing any lifting or slipping of the foot when pedaling. Ventilation of the S-Phyre RC-903 is provided by the thin, perforated microfiber leather on the upper, and by an air inlet under the front part of the carbon sole. Small holes for ventilation are also visible on the inner soles, at the front and back.

Finally, regarding weight, The RC-903s are lighter and weigh 218 g each in size 39., compared to 230 g for the RC-902, a gain of 24 g on the pair.

The S-Phyre RC-903 are available in four colours (white, black, blue and red), and from 36 to 48 (with half sizes from 37 to 47, in wide model (with an additional 3 to 4 mm of width on the forefoot) and in women model narrower from 36 to 44 (only in white).

The finish is superb, and completely compatible with a high-end sale price of €349, however slightly lower than many competing models which now flirt with 400, or even 450 €. We can also notice a replaceable pad at the heel, and a rubber protection plate at the front end of the sole, to limit damage in the event of friction with the front tire.

S-Phyre RC-903: comfort and performance

The fit is comparable to the RC-902 version, with a fairly narrow entry, and therefore excellent heel support, but with a front part where the toes have enough room to spread comfortably without overlapping. When tightening, the part on the instep is always quite surprising, because the very placement of the Boa wire offset from what is usually done eliminates this feeling of a strap on which one can lean when pulling on the pedals. Here, maintenance is globalized, without any hard points, and you have to rely solely on the progressive adjustment of the shoe around the foot to have the impression of being completely one with the whole bike. From our point of view, Acting on the two Boa dials is essential for tightening.

The very flexible material of the upper offers a lot of freedom at the front of the foot if the tightening is not properly done. But conversely, A powerful tightening is quite bearable over a long period of time thanks to the design of the shoe itself. It remains to be seen, however, how this softened microfiber leather will age, and whether it can continue to provide such good support and fit after being subjected to many difficult climatic conditions, which we were unable to verify after 1200 km of test.

The carbon sole is very rigid, but again it must be associated with the overall tightening, because it is not enough to ensure performance if the foot is not sufficiently maintained at the level of the upper. But once the correct tightening is applied, the sole, the well-closed heel and the wrapping of the upper around the foot literally pin it to the shoe to a very high level of performance.

We also appreciate the low arch of the sole which offers a very natural movement when pedaling. And above all, with Shimano cleats, we note that the placement of the cleats is done without the slightest deformation when tightening them, whereas it can happen that on certain other shoes they deform slightly and thus provide contact on the pedal with play.

Our opinion on the Shimano S-Phyre RC-903 shoes

Lightweight and comfortable, the S-Phyre RC-903 offers a minimalist fit that feels like wearing slippers, but can be significantly stiffened by applying a strong tightening, so as to truly become one with the shoe. The outsole provides good stability and natural pedaling that does not restrict ankle movements. The insole offers support customization options that are not so common even at this price point. And even if it's subjective, we find them very beautiful. It remains to be seen how the microfiber leather and mesh portion of the upper will age, both aesthetically and in terms of functionality.

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