Specialized S-Works Ares 2 vs Shimano RC9 S-PHYRE: Road Shoe Comparison
Both are flagship, sprint-focused road shoes from brands that dominate triathlon bike setups, but they solve the same problem — maximum power transfer with a genuinely secure fit — in different ways. Here’s how the Ares 2’s twin-BOA sprint shoe compares to the S-PHYRE RC9’s stiffness-first approach.
At a Glance
- Specialized S-Works Ares 2 — 224g (size 41), all-new Body Geometry last, twin BOA Li2 dial closure, claimed 7W power gain and 44% less forefoot pressure vs the outgoing Ares, ~£479
- Shimano RC9 S-PHYRE (RC903) — 496g/pair (size 43), dual BOA Li2 dials, full carbon outsole rated 12/12 on Shimano’s stiffness index, £299.99 at Tredz (RRP £349.99)
Specialized S-Works Ares 2
The second generation of Specialized’s sprint-focused race shoe brings a new BOA dial system paired with a wider toe box and reworked last for a more forgiving fit than the original Ares, which some riders found narrow. Specialized’s own claims — a 7-watt power increase and 44% less forefoot pressure — come from an updated closure that increases contact surface by 20%, plus an enlarged heel counter designed to eliminate heel lift during hard, high-cadence efforts. It’s genuinely one of the lightest race shoes on the market, but that comes with a price increase over the previous generation.
Shimano RC9 S-PHYRE
Shimano’s range-topping shoe prioritises raw stiffness and heel retention above all else — its full carbon outsole tops Shimano’s own stiffness index, and the anti-twist heel cup is built to hold your foot dead still under maximum power. It’s a favourite among WorldTour sprinters and puncheurs for exactly that reason. The dual BOA Li2 dials give precise, independent adjustment across the forefoot and midfoot, and at £299.99 (discounted from £349.99) it undercuts the Ares 2 while remaining one of the stiffest shoes you can buy.
Which Should You Choose?
If minimum weight and Specialized’s Body Geometry fit philosophy matter most to you — and you’re happy training and racing exclusively in Specialized shoes and cleats — the Ares 2 is the lighter, more race-specific choice, at a real price premium. If you want the stiffest possible platform for the money, with a fit that tends to work well for wider feet than the narrower Ares last, the RC9 S-PHYRE is both cheaper right now and arguably the more versatile shoe for long training rides as well as race day.
See our best triathlon bike shoes roundup for more options at every price point.
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