This article was first published in Rouleur Issue 143 and was produced in collaboration with Giro
Giro’s new flagship aero helmet, the Eclipse Pro, made its debut at the Tour de France in 2025 with Visma-Lease a Bike, where the unstoppable Pauline Ferrand-Prévot rode it to overall victory. In the men’s race, Wout van Aert wore it to cycling’s most prestigious stage win on the Champs-Elysées on the final day. The wins kept coming – Jonas Vingegaard in the Vuelta España, Kate Courtney at the Leadville 100, and most recently Paris-Nice 2026 with Vingegaard again.
Giro officially launched the Eclipse Pro to the public in February. We went to the brand’s Adventure Sports Hub in Barcelona to talk to the design team behind it, to find out how a claimed 17 per cent saving compared to the previous version had been achieved along with the startlingly low weight of 280 grams, and why the US brand was saying this was its “most advanced blend of aerodynamic innovation and performance protection to date, marking a new era for the aero-road category”.
First of all, in the world of professional cycling where gains have been getting increasingly marginal for around a decade now, when a new product can be considered successful if it’s just a fraction of a watt faster than its predecessor, 17 per cent sounds like an unfeasibly large number. That’s until you discover who Giro’s senior industrial designer Ash Lewin is, and which other large, watt-saving objects are in his palmarès.
Lewin is the man responsible for the Giro Aerohead II, the huge, ballistic missile-shaped time-trial helmet that burst onto the scene at Paris-Nice in 2024 and generated superheated debate at UCI HQ before they waved it through. Before we dig into the details of the Eclipse Pro, can we start with the story of the Aerohead II to set the scene?
“We saw that there was a burgeoning trend,” Lewin recalls. “Brands like Kask and Met were starting to go with a larger frontal profile, but theirs were rounder. We saw an opportunity, and it’s a really interesting story around how it evolved, especially with the UCI’s response.”
Lewin is based out of Giro’s California HQ and graduated from the Academy of Art University in San Francisco in 2020. He has worked on projects as diverse as the McLaren + S-Works Volar, a concept ‘hypercycle’, and the Rivian Basecamp electric campervan, the ultimate adventure vehicle. When he started thinking about the Aerohead II, as with these, he looked outside of cycling for inspiration, simply at fast objects: “The nosecone of a jet, a bullet train, and we also looked at things that are simply efficient, like a shark, a fish, or a whale that uses that ability to move cleanly through air or water.”
He’s talking about real-life rather than computational fluid dynamics. “I’m not an aerodynamicist, but there’s something beautiful about trying to solve a problem through simple logic. It started as a design hunch and we built that shape onto a scan of Wout van Aert and Jonas Vingegaard. It ended up being the fastest shape that we had looked at within the broad approach.”
Although the Aerohead II legitimised larger-volume TT helmets in the pro peloton, it was the approach rather than the shape that Lewin took with him into the Eclipse Pro project.
“We had a strategy, we had worked very closely with Visma-Lease a Bike and really, the success of the Aerohead II was not only down to their openness to experiment, but also the way they partnered with us to stand behind the design. So we took that momentum and built a new helmet with completely different design parameters.”
Whereas the Aerohead II had been all about pushing to the outer limits of the UCI’s bounding boxes – the maximum permitted dimensions – to create as large a fairing as possible, the Eclipse Pro, as a road race helmet, had to be as compact as possible.
Lewin and his team first looked at the Giro Aries, which offered the best balance of compactness, light weight and ventilation.
“We went back to a fully closed version to move air over the top of it. We refined the shape from there and ran a couple different iterations in parallel to see which would be faster. This was before we got to the point where we introduced vents.”
As Lewin explains, possibly the biggest challenge for the Eclipse Pro was to work out how to ventilate it while maintaining its aerodynamic performance.
“Typically, dirty air is not fast, so the cleanest air is that which we can move right over the top of an object with the least amount of resistance. Once you introduce air into the system, it's very tricky to remove it cleanly as it runs into so many variables. There’s the construction of the helmet itself with Mips Spherical [Giro’s patented impact protection system comprising two layers of EPS that slide against each other to reduce rotational motion] but also what happens when it meets the head, hair, and so on. Moving it cleanly out of the helmet is a problem. So first we looked at the overall speed we could achieve with the shape itself, then we needed to iterate on the vents and tackle certain targets with eyewear storage, which is always a demand of riders. And we also had to define where we would distribute the air most comfortably over the rider’s head.”
The design process starts in a fairly conventional way with pencil sketches. “It always starts with 2D. Almost entirely. We want to get a feeling for what we're trying to achieve. The aesthetic goals have to be balanced with the functional goals, form following function. Very quickly we knew that we had to validate with data – the design hunch has to be backed up.”
At the presentation in the Adventure Sports Hub earlier that day we’d all stopped at a table and cooed over cute miniature versions of the Eclipse Pro that looked as though they’d escaped from a Hot Wheels track.
“We do a lot of half-scale modelling,” explains Lewin, “and it’s a way for us to zoom out, especially at first. It’s like a visualisation tool, an evolution of the 2D sketches. Within a couple of days we can have numerous iterations out of foam. We can scan it, we can surface it and then we have something we can run into CFD – computational fluid dynamics. It’s very efficient for us to build and move quickly through that, especially with a truncated timeline.”
When he talks about a “truncated timeline”, he means the ten months that the Giro team had to deliver the helmet to Visma-Lease a Bike in time for the 2025 Tour de France.
As the design progressed, the team found themselves with two different shapes – a long-tail and a short-tail version: “There were probably half a dozen iterations across two different shapes. Within those, three or four refinements each. Ultimately the short tail had more advantages. It was more versatile for what we were trying to achieve,” Lewin says.
In road racing, when the rider is climbing or sprinting, riding on the hoods or in the drops, a longer tail can become an air-brake and Giro’s testing validated this. However, it also gave Lewin and his team a novel idea that they hadn’t deployed before.
“We decided to do a head-down and heads-up approach, with two different head positions to represent very dynamic riding. When we did that, we discovered that especially in heads down, we could move the air through a front channel, and that front channel splits into two different layers. We were able to really target the air that actually cools the brow and the base, where typically riders experience issues with eyewear fogging, or sweat build-up and drip. For me this was a very exciting innovation, something that translates to comfort for the rider as well as improving aerodynamics. We really went into the microscope and used CFD to tune the air this time.”
Handed over to the pro riders, the helmet began to prove itself in real racing immediately. “And obviously there have been a lot of successes since then,” he points out. But what would Lewin say is the biggest single innovation, the one that defines the Eclipse Pro?
“I wish there were one smoking gun,” he says. “Everything works in conjunction, there's the harmony of an entire system. And I think that's what's so humbling about the whole process.”
Having just launched a helmet with superior aerodynamics, an innovative venting system and low weight without compromising on safety, does Lewin ever worry about what comes next, where he’ll find new improvements?
“Design never stops, especially the pursuit of performance. We don't rest. And partnering with WorldTour teams, they absolutely do not stop. I think if it was an individual effort, it would be much more intimidating. But again, it's just incredible to collaborate with great minds. When we bring together our perspectives, the possibilities are endless.”
