The Shimano S-Phyre RC903 shoes are easily spotted in the professional peloton, such is their presence. Of course, there are those riders obliged by their Shimano-sponsored teams to wear them, but their take-up among those WorldTour riders able to choose their own shoes is testament to their performance.
That’s not a new phenomenon, with Shimano’s top-end shoes an ever-present in their various guises over the last nine years. Not too much has changed in a style sense, the RC903s still featuring a wrap-around upper with two Boas, a heel cup for stability, a low-stack sole, and vents at top and bottom.
It is proof of the quality of the range that they have subtly evolved over time rather than chopped up and started from scratch. The additions to the RC903s (launched in 2023) include reduced weight compared with the RC902s using a new layered build in the upper, along with a more rigid rear and new heel cup. Shimano described the make-up of the shoe as providing a “slipper-like fit” that “maximise power transfer while maintaining comfort”. But how exactly do the S-Phyre RC903 shoes shape up in the real world?
Ride impressions
Shoes will always be one of those areas in which it’s simply a case of finding what works for you. I’ve invariably stuck with my old S-Works 7 shoes despite having tested numerous alternatives over the years, enjoying the slightly wider toe box and the extremely secure lock-down of the Boa dials.
Out of all those shoes tested, I can safely say that the S-Phyre RC903s are some of the most supple uppers I’ve ever used. Whereas most shoes I’ve worn (including my old reliables) have come new with a certain rigidity that requires working in over time, it felt like the microfibre synthetic leather upper of these shoes conformed quickly to top of my foot with no irritation to be found.
I did however find the toe box slightly too narrow. That is a criticism that was levied at the RC903’s predecessor, the RC902. Shimano supposedly rowed back on this version to create a wider fit once again, but if I had the choice again I would opt for the wide-fit versions that are also available.
The nicest part about the wrap-around upper and the two Boa Li2 dials used here is that it’s very easy to find the right fit given the amount of adjustability. I can often find with Boa-equipped shoes that I end up overtightening to try and find a fit, but the forgiving nature of the upper felt like you could get away with that to a certain extent. The flipside of that is the fit didn’t feel quite as locked in for high-power efforts or sprints (perhaps why Shimano also has a ‘PWR’ version of these shoes), but over long endurance rides I couldn’t fault the fit provided by the Boa/upper combination and the heel retention was excellent.
The curse of white shoes, despite looking the best, is that keeping them clean and perfectly white can be an impossible job. I found the main part of the upper here (which extends under the midsole) held its colour over the short time I've been wearing them, although there was some immediate discolouring on the small upper vent after getting caught in one unfortunate shower.
There’s a noticeably low stack to the sole of the RC903s thanks to the way the upper and sole are constructed together, and there is certainly a distinctive direct feel to the pedals because of it. The carbon sole is, as you might expect, Shimano’s stiffest (rated a 12/12 on the brand’s own scale) and there’s more than enough here to handle whatever power I can muster. Likewise, they weren’t so stiff as to be uncomfortable over long rides.
There’s nothing particularly exceptional about the weight of the RC903 shoes compared to competitors, weighing in at 250g per shoe in a size 45, but they aren’t advertised to be a weight-weenie shoe. I can’t say while riding the weight was any concern to me, and they felt as good as anything I’ve used on long, hilly endurance rides.
Verdict
I think the Shimano RC903 S-Phyres are exceptional and well-constructed shoes with a lot of thought put into small comfort details without compromising on performance. I think the upper is one of the most comfortable I’ve used, however I would say that it came with a trade-off of not being quite as locked in on top compared to other more rigid shoes. That being said, the heel cup does an excellent job of keeping your foot in place during maximal efforts.
The main gripe has to be the width. Thankfully Shimano provides heaps of sizes, but it may take some trial and error to find the right fit for your foot. I’d say if you suspect you have feet on the wider side, the wide versions of these shoes should be the first port of call.
Nonetheless, despite these shoes being billed as full-on racers, I actually think they are possibly some of the most versatile in that category. They’re comfortable enough to be worn over challenges of any duration, while the performance characteristics lend them to even shorter track efforts.
At an RRP of £349.99, they’re a significant investment, but it’s unlikely you’ll be left disappointed by this nicely balanced pair of shoes.
