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Swiss Side Hadron 625 wheels available to pre-order

New model offers a performance advantage over the world’s best aero wheel, according to Swiss Side

Swiss Side’s new Hadron 625 aero clincher wheels, which the brand claims to offer a 1% performance improvement over ‘the world’s best aero wheel’, will be available to pre-order in a fortnight.

Swiss Side say that the results from their wind tunnel testing have been “unreal”, and claim that the Hadron 635 outperforms the ‘world’s best deep profile aero wheel’. Swiss Side don’t name this wheel, but they say it’s from a ‘big brand’ and it’s 82mm deep, so we assume (dangerous, we know) they’re talking about the Zipp 808.

Of course, these claims are based on Swiss Side’s own tests (see how the wheels were tested on Swiss Side’s website), and other brands would doubtless dispute the findings. We’re reporting the claims here, not corroborating them.

Swiss Side says that the 62.5mm-deep Hadron produces slightly more drag than this 82mm-deep reference wheel but that the overall performance, according to its own criteria, is better.

“For a slight 1.1% increase in drag, the Hadron offers 5.9% reduction in side force, combined with a delayed stall characteristic and improved high cross-wind angle performance,” says Swiss Side. “These characteristics in particular also offer benefits at low riding speed because for a given wind speed, the effective cross-wind angle is higher. Based on an aerodynamic efficiency performance function which gives a 70% weighting to drag and a 30% weighting to side force, the Swiss Side Hadron offers a 1% performance improvement over the world’s best aero wheel.”

So, the 82mm-deep wheel offers slightly better aerodynamics but the Hadron 625 is better overall, according to Swiss Side. As mentioned, the testing was done according to Swiss Side’s criteria and that 70% / 30% weighting to the findings is Swiss Side’s own rather than an industry standard.

Check out Swiss Side’s website to see exactly how the wheels were tested in the wind tunnel – everyone does it differently – and how those conclusions were reached. The brand says that it tested the front wheel only, then both wheels on a complete bike frame, then both wheels on a complete bike with a dynamic leg dummy. The published results relate just to the ‘front wheel only’ tests although Swiss Side says, “The relative wheel performance offsets and characteristics are the same as with the complete bike simulation methods.”

The Hadron 625 uses an aluminium/carbon rim that’s 27mm wide and a toroidal profile (the side walls are curved). The braking surfaces (23mm width) are aluminium. The hubs are forged and machined 6061 T6 aluminium with sealed bearings (ceramic bearings are available as an option) while the spokes are straight-pull Sapim CX-Rays, 18 radially laced at the front, 24 two-cross at the back. The wheels ship with a Shimano/SRAM 8-11-speed cassette body although Camagnolo cassette bodies are available on request.

Swiss Side say that the wheels weigh 740g (f) and 916g (r) – a total of 1,656g, not including QR skewers or rim tape.

The Hadron 625 wheelset is priced at €799 for EU customers, including VAT and shipping. That’s about £662 at the moment. They cost €665.83 outside the EU, exclusive of VAT and shipping. Those prices include skewers, rim tape and replacement spokes. If you want ceramic bearings, they’ll cost you an additional €125 (around £104).

You can pre-order at from 15 April, with orders expected to ship at the end of June.

Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now pushing 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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