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For ���������� alumnus Todd Carver, what he learned in the lab as a student inspired industry-rocking innovation in developing digital bike-fitting technology

For a long time, one of the unspoken truths of cycling was that if you ride hard and long enough, it’s going to hurt: foot or hand numbness, back pain, shoulder pain, the list is extensive.

Every rider feels it differently. For Todd Carver (IntPhys’00, MIntPhys’02), “my lower back is the problem. I struggled with my position but finally got to the point where I could ride pain-free as I understood the human body more and was actually able to make changes to my position on the bike.

“Plus, the bike’s adjustable, right, so you can move the seat, you can adjust your touchpoints to the bike, your hands, butt and feet can all be adjusted. And if you don’t adjust those and just plop yourself on the bike, there’s a chance you’re not going to perform well and you’re going to get injured.”

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���������� alumnus Todd Carver (IntPhys’00, MIntPhys’02) co-founded Retül, a bike fitting and product matching technology now used by professional cycling teams, performance centers, rehabilitation centers and bicycle retailers worldwide.

While working with Bill Byrnes and Rodger Kram, associate professors emeritus in the ���������� Department of Integrative Physiology, in the Applied Exercise Science Laboratory during his graduate studies, Carver began wondering if competitive cycling—or even long-distance recreational cycling—needed to end in pain.

“The big thing the cycling world was missing was information about the rider—the human aspect,” Carver explains. “How should riders fit on a bike? How do you position a rider to be powerful, efficient and perform well? All the things I was learning in my academic career under Bill Byrnes and Rodger Kram—the focus of my research—was in predicting cycling performance, who’s going to perform well and who’s not.”

The problem was, there just weren’t that many tools to assess a rider’s position on their bike and give them a three-dimensional, dynamic bike fit. So, Carver and two colleagues developed one: Retül, a bike fitting and product matching technology now used by professional cycling teams, performance centers, rehabilitation centers and bicycle retailers worldwide.

Retül wrought such a change in the cycling world that Specialized acquired it in 2012. Now, as head of human performance for Specialized, Carver continues to innovate at the vanguard of cycling fit and performance.

“Riders just want to be pain free,” Carver says. “And even if they don’t care about being fast, they don’t want to push on the pedal and not go or push on the pedal and it hurts.”

Bike = freedom

Carver discovered young that pushing on a bike pedal is bliss and freedom in equal measure. “My first bike was a Huffy, and it was frickin’ rad,” he recalls. “As a kid, I realized that on a bike I can go way farther. So, I had this Huffy that I rode around the neighborhood, and it gave me a lot of freedom as a kid.”

His first “real” bike as a recreational and then competitive cyclist was a mountain bike, which he rode while figuring out what to do during the several years he lived in Breckenridge between high school and college. “I moved to Breckenridge and just got hooked on endurance sports, especially mountain biking, and I said, ‘I need to go study the science of this.’”

He came to ���������� and joined the cycling team, eventually realizing that he didn’t want to pursue professional cycling and that the science of riding held a lot more fascination for him. Plus, he brought to the performance lab and insiders knowledge of the problems cyclists could have.

“One of the studies that we did with Rodger (Kram) was measuring aerodynamic drag on bikes, and I saw how big of an opportunity fit was,” Carver says. “You can have a really fast bike, and that’s good, but the human body makes up 80 to 90% of drag.

Todd Carver (left) works with a cyclist to gather data for a bike fitting. (Photo: Todd Carver)

“To this day, we still do that analysis with all of our pro riders. We take them to the velodrome, measure aerodynamics and then work with fit to try to improve it. I’d almost say that one of the biggest impacts we’ve had is helping send professional and career cycling more toward science.”

After earning his master’s degree, Carver worked at the Boulder Center for Sports Medicine, where he and an engineer colleague, Cliff Simms, soon realized that people were flying in from as far as Europe to get fitted for bikes. He wondered why they couldn’t get fitted in their hometowns, “and it really came down to the technology. For a bike shop to get the digital technology was too expensive and it was too hard to run—you basically would need a master’s degree in biomechanics to do it—so this engineer friend and I started to look at how we could break down those barriers.”

They began developing a motion-capture system that measures length and trigonometric relation between small LED markers placed all over the cyclist’s body and synchronized to flash at certain times, a process that happens in milliseconds. 3D cameras positioned around the rider record the data, which is immediately analyzed and used to fit riders to bikes with millimeter precision.

Affordable, portable, easy to use

With partner Franko Vatterott, Carver and Simms founded Retül in 2007 with a goal of making bike fitting more affordable, portable, easy to use and data driven.

“I say I got my MBA starting a company,” Carver says. “I knew nothing, and I learned it starting a company. One big thing we learned is you better have a darn good product, and what we felt we had was a really good product, so that made some things easier. We didn’t need to take investment initially; we were able to just bootstrap it and work off the money we were making (during development).”

They also were building a database containing everything they were learning about different types of bodies and how they fit on bikes—data they knew would be appealing to bike manufacturers. In fact, he adds, the goal was always to sell to Specialized, which had worked with doctors on ergonomic design and lacked only data from digital fitting.

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Todd Carver (right) shows a cyclist data from a digital bike fitting. (Photo: Todd Carver)

They initially worked with professional riders, drawing on connections Carver had made with riders in ���������� performance labs, and marketed Retül to fitting pro teams. “Then bike shops were coming to us saying, ‘We’d like to buy one of your systems.’

“From the rider point of view, what I was hearing was, ‘Wow, that feels way better, and it’s easier for me to pedal’ or ‘That completely got rid of my injury and now I can push harder.’ The problem might not be the bike itself, it just might be the saddle or the shoe or the footbed, or it just might be that the rider needs to reposition themself on the bike. From the rider point of view, that’s powerful because they could see that bike shops weren’t always trying to sell them a new bike, but had the data to say, ‘Let’s try a new saddle.’”

‘More fun with data’

As head of human performance for Specialized, Carver continues to work with riders at all levels and in all areas of cycling.

“We work in optimizing athlete and product performance using science,” Carver says. “In addition to fitting pros and selling fit systems to retailers, we do a lot of research and development—we take that fit knowledge we have and are able to then use that for ergonomic design of saddles, shoes and hand grips.

“How hand grips are shaped, for example, affects how a rider’s hand sits, which can mean the difference between a comfortable hand and one that goes numb. So, what we do is prototype and test and gather data for better design. We do so much work in saddles, which is the hardest thing on a bike to get right, so we’re always testing with pressure mapping.”

The overarching goal, Carver says, is to solve riders’ problems, “and that’s more fun with data.”

Carver often considers whether his life’s work is science or art, and figures it lives somewhere between the two: “We use scientific tools, have all these ranges, but we can’t know everything from that. I think that’s where the art comes in. You need to work with a lot of different riders—some who just want to ride bikes down to the grocery store and don’t want to be aerodynamic or fast—and you have to be able to empathize with that as well as the more competitive side of cycling. You have to have the human side, too, and really read people, have really good interviewing skills and listening skills to know what they want to do on a bike.��

"I think I can empathize because I still love to ride, and I still feel that freedom when I get on my bike.”

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