Swiss Side rolls over and adds a UCI-compliant 65mm deep option to its Hadron range but the rebellious amongst you can still buy the illegal 68mm

Two weeks before launching its new deep section race wheel, the Hadron Ultimate 680, Swiss Side received some bad news. The UCI had announced that, come January 1st 2026, the rim depth for its sanctioned road events would be limited to a maximum of 65mm. As the name suggests, its new hoops measured 68mm.

Given that the Swiss aero experts had spent more than two years developing the Hadron Ultimate 680, it was, as it described “a major and unexpected and extremely costly blow”. The Swiss aren’t known for their hyperbole so it's fair to imagine that the UCI ruling was as harmful as it stated. But you can’t keep a good engineer down, with Swiss Side’s response swift. Meet the Hadron Ultimate 650.

This “UCI-compliant solution” uses the blueprint of the 3rd generation of Hadron wheels that were launched early this year, featuring the same 22mm internal rim width and the v-shaped rim that’s designed to reduce aero drag while making the wheel as predictable as possible in crosswinds,

The changes to the UCI rules were made with safety in mind, a result of a belief that deep-section wheels could, at a certain depth, become too erratic and unstable in crosswinds, so Swiss Side doubled down, reducing the steering moment (how sensitive a wheel is in a crosswind) of the 650 by a further 12% compared to the 680, while making it half a watt faster and 33g lighter.

"Despite the undue challenges brought by the impact of the UCI rim depth limitation on our brand, business, and supply chain, thanks to our sensational team and partners, we have been swift to react under pressure,” says Jean-Paul Ballard, CEO and Co-Founder of Swiss Side “The HADRON³ Ultimate 650 is our definitive answer: the fastest and fully UCI-compliant wheel available, delivering ultimate performance and safety, at the absolute limit of the rulebook.”

But the complaint wheel wasn’t Swiss Side’s only riposte. It sent an open letter to the UCI scientifically challenging the 65mm depth ruling. With over ten years of data on its side it set out to show that rim depth actually has a “limited impact on stability, predictable handling and safety”. It did so by showing the results of some testing, with the 680 pitted against UCI legal wheels - on 60mm, the other 50mm - currently used in the professional peloton. All fitted with 28mm tyres, the results showed that the soon-to-be-banned 68mm rim was actually the “the most stable and quantifiably safe wheel from its aerodynamic characteristics”.

In today’s parlance, a ‘mic drop’ moment, except Swiss Side don’t seem concerned with scoring points rather than playing a part in better equipping the UCI with the necessary scientific data so it can make more informed decisions when it comes to its decisions on the usage of equipment in its races. The letter went on to read:

“The purpose here is to show the importance of an objective, science-based approach, which needs to be a part of the decision-making process for implementing equipment regulations. The recently proposed limitation on the rim depth to 65mm for 2026, can be objectively shown with regards to the steering moment, and the front wheel handling characteristics, to be ineffective and even counterproductive in bringing any improvement in wheel stability and thereby rider safety.”

Of course, for those not competing in UCI-sanctioned road events the 680 remains available and a valid option for triathlons or for anyone with a need for speed. Alternatively, the 650 is available, proceed at €2,699 or €2,159 if you buy a set direct from Swiss Side.