How would an end to UCI 3:1 rule affect bike design? Experts have their say

With no 3:1 rule limiting bike design will we see a return to radical designs like Chris Boardman's iconic Lotus? We asked the experts

Having learned the news that the UCI may scrap the rule limiting the aerodynamic design of bikes we spoke to some leading experts from the industry about the possible implications of this change.

Paul Lew is an aerodynamics expert who has previously worked for Reynolds and now designs wheels for Edco. Lew was present at the World Federation of the Sporting Goods Industry (WFSGI) committee meeting on Tuesday where the UCI is reported to have decided to drop the rule.

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Currently, under UCI rules the ratio between the length and the width of bike tubes and other components cannot exceed 3:1. The UCI itself has yet to confirm a change in its rules relating to frames.

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When asked how he thought it would impact bike design, Lew responded: “A lot of manufacturers have really been able to optimise aerodynamics with the 3:1 rules. We will see some trends moving away from it, but I don’t think there will be anything super radical, as bikes still have to have a double triangle.”

Will the rule change see a return to designs akin to Chris Boardman’s iconic Lotus, or perhaps bikes with filled-in front triangles?

Not according to Lew, who explained: “within a bike frame the tube must still be able to fit within a rectangular box. So, with regards to the front triangle, you can’t fill it in. It also means I couldn’t take the downtube and follow the contour of the front wheel.”

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Lukas Schuchnigg, Product Engineer at Canyon worked extensively on the new Canyon Speedmax CF time trial bike launched earlier this week.

He described that at Canyon “we make triathlon bikes too and in triathlon we don’t have the 3:1 rule. Consequently, we have thought for a while about if we were to design a bike right now, without the rule, how much different would it look to a current TT bike?

“We came to the conclusion that there wouldn’t be much difference to what we have now. For example if you look at the tubes on the current Canyon Speedmax we are inside the 3:1 rule, but if you were to extend the tube into a full aerofoil, we don’t think there is any benefit.”

When asked why a full aerofoil was not optimal Schuchnigg replied, “you are just adding more volume and weight. A deeper profile creates more pressure from side winds and greater instability.”

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Massachusetts-based bike brand, Parlee has a reputation for innovation and aerodynamics. Tom Rodi of Parlee explained that although a very deep profile tube may not be the best solution, we may still see them.

“It’s interesting, I think some brands will instantly jump to very deep sections because there is a perception visually that those are faster,” Rodi said.

With all this considered what are the actual beneficial changes we are likely to see? Lew says: “I think we will see tubes that are thinner with less frontal area and also a little deeper.”

Schuchnigg told us that “Canyon will look at all the details, but we don’t expect there to be big changes. Little things here and there are more likely.”

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Rodi had a different answer: “We will see things we don’t expect, because it is not just about aerodynamics. It opens the door to do things structurally that we couldn’t do before. For example there might be a head tube area where you would like to add more material for strength, but couldn’t before.”

Rodi was very enthusiastic about the news though and explained: “Giving designers freedom is great and there was certainly a lot more excitement about bicycle design in the 1990s when composite materials started to come in and we saw the Lotus bike and GT super bike from Atlanta 1996.

“Many early carbon triathlon bikes were very wild compared to what we have now.”

Product development cycles are long, so the likelihood is we will not see any big changes for a while.


The UCI responded with a statement addressing the situation on the rule in a statement on Friday evening, confirming that it would be amended:

“The UCI Management Committee recently approved the removal of the specific clause in its Regulations relating to profiles in frame construction. The amendment, entering into force in January 2017, will have a marginal impact on frame design. But it is important that our sport embraces innovation and evolves with its times.”