TT bikes sans UCI rules: faster or fashion?

Peak aero or history repeating itself? What the latest prototype bikes, Ironman and the fashion industry tell us about a new crop of aero bikes.

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Fashion has a “20-year rule”, a cyclical concept that suggests that 20 years is about the time it takes for a trend to die off only to come full circle and become fashionable again. Striking aero monocoque frames, beam bikes, and missing tubes were all in vogue as 1990s bike designers went carbon on the brain. Then the UCI came up with the Lugano Charter and sentenced such designs to the road racing fashion scrap heap.

First penned in Lugano, Switzerland, in October 1996 before coming into force in 2000, the charter was the UCI’s way of ensuring bikes kept looking like bikes and cycling avoided becoming an arms race. As such, the Lugano charter spelt the end for the iconic bikes of that era like the Lotus Sport 108, Obree’s “Old Faithful”, Zipp and Softride’s beam designs, and the Giant MCR.

For the past 22 years, these bikes lived on with a cult following in triathlons. But with bike manufacturers mostly focused on creating UCI-compliant bikes, many of these iconic frames were discontinued. Even triathlon-specific bikes looked a lot like the UCI idea of how a bike should be with double diamond frame designs, albeit with bigger tubes and built-in watering holes. But does recent frame design suggest the 20-year rule might be at play in the bike industry? And might we finally get an answer to what a bikes would look like free of UCI constraints?

Ah, the 90s.

20 years after the Lugano Charter, Cervelo launched its P5X and beam bikes were back, sort of. The P5X was a true “forget the UCI” bike from one of cycling’s biggest manufacturers, ditching rules and tubes left, right and centre.

It was around this time I heard the “how aero could a time trial bike be if we had no UCI rules?” question start gathering pace. The seemingly standard industry answer over the past half-decade was something along the lines of “not all that different”, “the double-diamond is highly optimised”, “physics dictate”, and “the numbers suggest.” But the question persisted.

Bring back the Lotus!

Then Ventum and Tririg offered their opinion, unveiling their very Lotus-esque machines with the One and Omni frames. Highly UCI illegal and extremely fast looking, if the Cervelo P5X was the return of the beam bike, these were the return of the Lotus.

Fashion’s “20-year rule” or just copyright expiration? Either way, that seemed to be it. Even as manufacturers’ shifted to designing faster triathlon bikes with watered-down versions to meet UCI regulations for road riders, most bikes retained the double-diamond frame design. The UCI-rule question mark hung over both tri and road frame designs. Is this peak aero or are the Lugano Charter, safety, or even just aesthetics, still influencing bike design in both sports?

The Ventum One triathlon bike. First released in 2016 and recently updated, the bike bears a resemblance of the iconic Lotus 110 of the 90s.
Chris Boardman was fond of a Lotus or three.

The acceptance, understanding, and focus on aerodynamics have come a long way in cycling, even in the six years since the launch of those three bikes. Just look at the Lotus Hope GB track bike. Those advancements and the combination of a covid-delayed Ironman World Championships and the relaxation of some UCI regulations on frame design seem to have created the perfect storm in the TT/Tri bike world. With the 2022 Giro d’Italia time trial and the 2021 Ironman World Championships both happening this weekend, the past month has seen an unprecedented number of new aero machines unveiled all leaning on advanced aerodynamics or the new UCI rules.

This week alone BMC and Colnago both treated us to new time trial bikes. Rumours abound of a new time trial bike from Pinarello. While both Wilier and Scott have popped up on the UCI list of approved frames with new time trial bikes. We’ve also seen a new UCI legal Time Warp TT from Merida and triathlon-specific Felt IA 2.0.

Perhaps most interesting of all the new aero bikes, though, is a frame from Cadex for triathlon Olympic gold medalist Kristian Blummenfelt. The frame is a first for Cadex, a components brand but it’s not even the first “funny bike” for parent company Giant bikes. The UCI penned the Lugano charter in 1996 just as Giant was developing its MCR frame in the mid-late nineties. As the new rules came into force the MCR disappeared along with the other innovations of that era. But whether it’s fashion trends, UCI rules, or aerodynamic developments on a 20-year cycle, the new Cadex is undoubtedly a descendant of the MCR.

That said, descendant of a 90s bike thought it may be, the new Cadex frame exhibits plenty of modern innovation. Innovation in the form of seat stays almost identical to those on the new Colango and forks that look like the offspring of the Hope HB.T and the Specialized Shiv Disc. The Blummenfelt video also gives us a glimpse of a new four-spoke tubeless aero wheel from Cadex, presumably replacing the brand’s current four-spoke tubular offering. Cadex seemingly has a tubeless disc on the way also, based on the Continental GP5000 tyres spotted in these photos from

As with many of the new bikes this week, Blummenfelt’s new frame is still in prototype form and Cadex, nor Giant, were willing to divulge any information. Without aero testing data, it’s difficult to see how the lack of a top tube offers any significant aero improvements. But in the absence of confirmed information, we have the freedom to speculate – and not on the aerodynamic efficiency of the new frame, but rather on what the very existence of a frame from Cadex might suggest.

Giant revived the Cadex brand in 2019 as a high-end performance wheels and components offering. Blummenfelt races on Giant bikes and Cadex wheels, so nothing new there. But why put Cadex branding on a new frame? We see two possibilities. Cadex frames are the manifestation of Giant designers expressing their engineering minds set loose from the shackles of the UCI rules. Or, perhaps Giant is extending the Cadex brand into bikes and frames with a high-end, ultra-expensive offering as the goal?

One thing is for certain: the Cadex frame will never make a UCI start line and the Giant Trinity time trial frame is due an update, with Cadex (and Giant) developing this tri-specific bike presumably alongside parent company Giant developing a new UCI legal time trial bike. All at a time when the understanding of bicycle aerodynamics has never been greater. Might we finally get an answer to the age-old question of what the fastest bike looks like?

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