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Gravel Gear

Talking wheel design with aerospace engineer Luisa Grappone

Aerodynamics are a thing, even in gravel. After years at 3T and Campagnolo, Grappone is now driving wheel design at Hunt.

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For the last 11 years, engineer Luisa Grappone has worked in the design, development and production of bike wheels. Although she was trained as an aerospace engineer, the Italian wasn’t happy staring into the fuselages of Boeing 787s, so in 2009 she took a chance on a job at 3T Cycling. After nine years at 3T and then Campagnolo, Grappone moved to the United Kingdom to head up an engineering team at the burgeoning Hunt Bike Wheels. She’s been in Brighton for nearly four years now, and, aside from the weather, couldn’t be happier designing, developing, and managing the entire product lifestyle of a host of carbon and alloy road, gravel, and mountain bike wheels.

We spoke with Grappone from her home in Brighton, as she tried to navigate the challenges of Brexit, COVID-19, and rainy British days, on her work as engineering and product manager.

VeloNews: Was it hard to leave a legendary company like Campagnolo for a start-up in the UK? 

Luisa Grappone: There was a good team at Campy. We were bringing new ideas but it was often stopped because the management couldn’t see it. At Campy, not all of them are cyclists. The young guys are getting closer to that, but many of the guys working in the marketing department weren’t. You could see how they couldn’t really understand the bike world because they weren’t part of it. I wanted to go back and be part of that world like I was at 3T. At Hunt, it was like that. 

luisa grappone
Grappone at the commands of the wind tunnel. Photo: Dan King/Breakaway Media

VN: What was gravel wheel development like when you started at Hunt?

LG: 27- to 32mm was the max for gravel. Gravel racing was coming from the U.S., and people were starting to ask for those parts of design. We did a lot of testing, wind tunnel tests and found that even if you put a big tire with those big knobs where the aerodynamics of the rim could be compromised because of the tire, a deeper rim still brings aero advantages. 

People want to be light, even more in gravel because you bring a lot of stuff with you. It’s not like making carbon rims for road where you are 99 percent sure you won’t break or hit anything. With gravel, probably 10 times out of 10 you will hit a rock, so your rim has to be light and have the strength for that. We have done a lot of testing on the layup to make sure we could achieve a good compromise of weight and level of strength that you won’t break your rim by hitting a rock or going over roots. 

VN: Do you enjoy the challenge of designing gravel wheels? 

LG: It adds a lot of work. It’s great because you have to look at optimizing the layout, thinking about new tech, and new kinds of material. It’s something we’re working on, a mix of things for MTB and gravel. We’re trying to make possible the use of a different material that would absorb impact and give you that compliance. You still want that stiff rim that carbon would give you. You’re riding 100 miles on gravel, already feeling the stress of the surface, if we could avoid that and get ride of vibration….that’s challenging. We’re doing research on what’s out, what’s the latest in terms of materials, carbon fiber, and application that we could use, and then try to make that possible.

hunt
It’s not just about the rims. Photo: Courtesy Hunt Bike Wheels

VN: How is testing gravel wheels different than testing other wheels? 

LG: In the wind tunnel for gravel it’s completely different. With a gravel tire, no matter which tire, if the rim is shallow or deep you have the lowest drag at the front. As soon as you increase your angles, because of the knobs, drag increases drastically. 

We did a test where a shallower rim had 10x higher drag than a deep carbon or optimized aero shape for gravel. The tires mess up everything! When I first did it, I’m like, we did something wrong, let’s repeat the test. That can’t be possible! We did the test four times. You have to change the tire, change the rim. It’s physics.

hunt
The 35 X-Wide is a stiff and burly gravel wheel. Photo: Courtesy. Hunt Bike Wheels

VN: What is one thing that matters when designing wheels that’s not the rim itself? 

LG: The tire. The tire gives you a completely different feeling. Before there was belief that ‘oh, if you ride at high pressure your wheel is fast.’ In the end, no, it’s harsh. You feel all the vibration. You think you’re faster, but you’re not. Your arms and body are so stressed that you won’t be able to complete your ride. That was something I had to be patient with.

The English women’s team was starting to ride our tubeless wheels for the first time ever. They’d always ridden clincher and shallower rims. We gave them carbon rims, a bit deeper, tubeless. First of all, they didn’t want to ride 28mm. ‘I don’t want that, more volume resistance!’ Look, it’s completely the opposite. With a narrower tire, you have a longer contact patch because the tire is smaller and makes a long patch. A wider tire creates a balloon on an ellipse so in the end a lot less contact patch and less rolling resistance. Two surfaces in less contact with each other for a shorter time. 

luisa grappone
Grappone has a master’s degree in aerospace engineering from Università degli Studi di Napoli Federico II. Photo: Dan King/Breakaway Media

If you ride with a lower pressure, you again have a bigger balloon size, so the rolling resistance of the tire is less and you will see much more comfort in your body. That was hard for them. I told them, ‘look, I don’t want to force you, you need to listen to my suggestion but tomorrow go out and ride as you were doing yesterday, don’t mind what I was telling you. Keep the same pressure but change the tire and tell me if you feel something different. If you agree with me, change the pressure.’ In] the end, they wanted to run six bars.

It’s tire pressure, tire width, rim, the material, the combo of everything. 

VN What project have you been involved with at Hunt that you’re most proud of?

LG: Definitely I can say one of the projects I am most proud of is the 48 Limitless Aero Disc. First of all it is the very first project I worked on when I joined Hunt, and I was given carte blanche on the project.

I had ideas on the most aerodynamic performing profile for years, but I have never had changes to make them possible where I was working before as they were probably a bit too “ahead of time” for them. At Hunt, where the use of tubeless tires, for example, has been adopted years ago and innovation and new technologies and applications are our driven engine, it was quite easy for me to present a project where the use of an extremely wide rim (35mm, when no other wheel company was not even close to 30mm four years ago).

And when I got the confirmation at the wind tunnel in January 2018, when I went to test the first 48LAD prototypes, oh that was one of the best moments of my career. Not only did I get the confirmation that my ideas were correct, [but] it was also a sort of settling accounts with those who never gave me credit. Then when more and more brands started to come out with similar rim designs, that was for me an additional recognition of my hard work and efforts.

VN: Do you see yourself working in cycling forever? 

LG: When I was working for 3T, and I was team liaison I spent a lot of time with the Cervélo team. Their women’s team was one of the first cool proper women’s teams at that time. Emma Pooley, Lizzie Armistead [Deignan], Kirsten Wild, they were all there. It was one of the first teams where those girls were paid almost as much as their male colleagues. I would really love to really get to that point one day, to be the owner or director of a team like that and bring innovation and women to cycling. I see myself in the industry until I retire.