Shimano S-Phyre RC910 review: still just as stiff, but wider

Shimano is updating its top-end road shoes with the S-Phyre RC910. What’s new: a reworked cleat adjustment range and a wider forefoot that gives the toes a bit of breathing room. Otherwise, the Japanese brand isn’t tampering with a winning formula. The ultra-stiff carbon sole, the dual Boa dials and the wraparound upper are all still here. After several weeks of use, the verdict is positive overall, but this new last shape won’t suit every foot.

By Guillaume Judas – Photos: ©3bikes.fr

Straight out of the box, the RC910 clearly shows its lineage from the RC903. The styling barely changes, and neither do the materials or the closure mechanism. Two Boa Li2 dials independently control the instep and the front section, while the upper wraps around the foot as it tightens. Up front, the small mesh window is still there. It follows the deformation of the upper under tension, although its real role depends a lot on the shape of your foot and how tight you do the shoe up.

No revolution underneath the shoe either: the upper attaches directly under the sole, with nothing in between. As a result, the shoe’s stack height is lower and the foot sits as close as possible to the pedal axle.

As for materials, it’s familiar territory with a microfiber upper that is easy to clean. Only the white mesh tends to go a little grey with the miles.

Inside, the insole keeps its adjustable arch support thanks to interchangeable wedges (medium or high) supplied in the box. In short, Shimano is refining its benchmark model without starting entirely from scratch.

A Sole That’s Still Just as Stiff

Underfoot, the carbon sole keeps its signature characteristics: flat profile, wide support surface and maximum stiffness. No surprises compared with the previous generation. It doesn’t flex a hair when you stamp on the pedals, whether seated and grinding a big gear or out of the saddle. Still, an ultra-stiff sole isn’t everything. The foot also has to stay put inside the shoe.

A Noticeably Wider Forefoot

This is the real novelty of this model year: the volume gains 4 mm of width at the front on the standard version. You feel it from the first pedal strokes. The toes can breathe, a real plus for those who normally feel cramped in race shoes. The catch is that this freedom has a downside.

Out on the road, my narrower right foot tends to slide around a little too much once the pace picks up. In endurance mode, the comfort is superb. But when it comes to putting out watts, the hold starts to break down. Pushed to my limits on that right foot, I ended up cranking the front Boa dial to the maximum to try to lock everything down. The system quickly shows its limits: there is so much space that extreme tightening crumples the upper into ugly, stiff creases that end up irritating the foot. I had glaring proof of it in Italy, on a climb with ramps above 10% over five kilometers. At that pace, the difference in hold between my two feet becomes a real handicap. A caveat, though: my right foot is 4 mm narrower across the metatarsals than my left, a chronic imbalance of mine.

I have no doubt that this roomier fit will delight many riders. But it means being surgical when choosing your width, among the three versions offered in the S-Phyre range: standard, narrow (a slimmer cut) or wide (even wider!).

Excellent Hold Everywhere Else

This reservation about the forefoot shouldn’t overshadow everything else. Instep and heel, the fit here is a textbook example. Once the Boa is adjusted, the foot is locked in place, with no unwanted movement. Provided, of course, that the overall volume matches your anatomy.

A Wider Cleat Adjustment Range

Under the sole, Shimano has lengthened the mounting slots so the cleats can be moved back or forward more easily. A real plus for setting up the new SPD-SLR system (like the Dura-Ace PD-R9300), whose mechanism is different. With this new system, fore-aft adjustment is no longer made in the same way, directly at the cleat. It therefore becomes especially important to have enough positioning range on the shoe.

This change has raised questions about compatibility with other brands’ shoes. I tried it with Q36.5 Unique Pro and Nimbl Ultimate shoes. In both cases, the adjustment range seemed sufficient to fit the new cleats and find a suitable position, as long as you aren’t looking for a particularly extreme setup.

A Contained Weight

On my scales, the new S-Phyre in size 40 and standard width comes in at 219 g per shoe. That’s competitive, even if at this level of the range, stiffness and hold far outweigh a few grams saved.

Priced at €379, the RC910 sits at the lower end of the very top-end bracket. The price stings, but it is consistent with the level of finish.

Choosing the Right Version

The S-Phyre RC910 keeps the brand’s DNA: an ultra-stiff sole, impeccable instep hold and a perfectly judged closure.

But the wider forefoot may change the benchmarks. While it will delight wide feet, it penalizes slimmer builds like mine that are looking for surgical precision. Offered in three widths (Narrow, Standard, Wide), these shoes demand a careful fitting to find the right version. At €379, it’s best to make sure your foot doesn’t swim in the shoe before investing in a model that is known to be effective and durable given the materials chosen.

The Pros

• Finish
• Stiffness
• Instep hold
• Effective Boa system
• Available in three widths

The Cons

• Require a careful choice of width to avoid discomfort at maximum tightening

SPECIFICATIONS

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