The Origins, Evolution, and Future of the Tri Bike
Physics rules the highly-specialized tri bikes, from the seatpost and frame to the way a rider sits on it.
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From a kid’s tricycle and BMX bikes to beach cruisers and road race bikes, it’s clear that not all rides are equal. There’s something for every need, every age, and increasingly, every two-wheeled sport.
In triathlon, the best bikes usually are triathlon-specific bicycles, more commonly known as “tri bikes.” Many triathletes start their cycling journey with road bikes, and tri bikes could be considered an evolutionary offshoot of this type of cycle. But tri bikes have developed into a distinct breed of vehicle, designed for the unique demands of multisport athletes looking to maximize efficiency.
The Road Bike, Evolved
The most obvious difference between a road bike and a triathlon bike is the handlebars. Where a road bike has the traditional ram’s horn curved handles with integrated brakes that are familiar to anyone who rode a 10-speed as a kid, the tri bike forgoes that design for a long set of aerobars.
But look beyond the bars, and you’ll start to notice a lot of other differences, too. “The whole reason someone buys a tri bike is the angle of the seat,” says Brian Hughes, owner/manager of FastSplits, a multisport specialty store in West Newton. Hughes is an in-demand bike fitter who specializes in triathlon bikes. That seat angle is “a lot farther forward” than in a traditional road bike, an advance that was pioneered by Dan Empfield.
Designing a Bike Specifically for Triathlon
These days, Empfield is known to many as Slowman on Slowtwitch, the expansive triathlon-focused website he founded in 1999. But Empfield came to Slowtwitch after a pioneering career at the helm of Quintana Roo, a triathlon-specific wetsuit company he founded in 1987, sort of by accident, he says. “It just happened through circumstance and freak luck,” because to make the wetsuits he’d designed specifically for triathletes, he needed to build a factory.
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About the same time that Quintana Roo, which was named for one of Empfield’s favorite travel destinations in Mexico, launched, another inventor named Boone Lennon also produced a breakthrough piece of equipment designed specifically for triathletes. Lennon had grown up a downhill skier and became head coach of the U.S. World Cup Alpine Ski Team in the mid-1980s; he used that innate understanding of physics and aerodynamics to create a new type of handlebar that helped cyclists get into a very streamlined position to cut wind resistance.
Essentially a sinuous tube of metal with armrest pads attached, the bar, manufactured as the SCOTT DH Handlebar, encouraged riders to shift forward and rest the upper body in a slim, aerodynamic shape.
As with the specialized wetsuits that had suddenly arrived, these aerobars increased efficiency and speed, helping athletes reach the finish line faster. “Both of these new technologies debuted in early 1987 pretty much simultaneously,” says Empfield. “I was doing triathlon myself pretty vigorously at the time, and we were all figuring out how to best ride that handlebar. We knew that if you put the handlebar on your bike, that it was an improvement on standard road bike handlebars.”
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Yes, it’s a Weird Position – and it Works
This new position wasn’t terribly comfortable, though, so Empfield and other athletes and equipment designers began tinkering with their bikes to find the sweet spot. “We started with the bar and everything from the bar back was a detail. Everything was on the chopping block,” says Empfield. “There was no stem, no seat post, no saddle, no frame design. There was nothing more important than the bar. Everything was subordinate to the bar.” From that foundation, they worked out how to more comfortably get into that low-surface-area, crouched stance this has become an iconic image of the sport.
Eventually, “it became apparent that the saddle needed to be much farther forward to ride that bar effectively than it’s typically positioned on a road bike.” Broadly, the addition of the aerobars changed triathlon bikes from the typical road bike position into a “forward recumbent bike. You don’t rest skeletally on the saddle and muscularly with your hands on the handlebars the way you do on a road race bike,” says Empfield.
Instead, when riding a triathlon bike, you rest yourself skeletally on both the saddle and the handlebars. The upper body is “completely at rest. No muscles are activated when you’re properly positioned on a tri bike. What that means is that you can move the whole cockpit of the bike rearward or forward. You can place it wherever you want without the penalty that you would pay on a road race bike when moving the saddle too far forward.”
So that’s what they did. “We put deep posts on our road brace bikes that moved the seat maybe 6 or 8 or 10 centimeters forward, versus what it as on a road race bike, and we adjusted the front of the bike accordingly. Riding the bike that way gave us a lot more speed and a lot more comfort.”
To better describe the new approach to designing a bike for efficient pedaling rather than the drafting of the peloton and to help cyclists navigate the expanding universe of tri bike options, Empfield coined the term “stack and reach” in 2003. “Simply put, stack and reach is the rise and the run from the bottom bracket to the head tube at the top of the frame,” Empfield explained. Tri bikes have a lower stack and a longer reach than a road bike fit for the same rider.
Hughes says the concept of stack and reach soon jumped from tri bikes to other bikes, and “essentially redefined how we measure bikes across the gamut.”
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Engineering for the Human Engine
In moving the center of gravity forward to streamline the rider and reduce strain on the upper body, that also offers the hips an opportunity to open up further, Hughes explains. This enables the athlete to better recruit power from the glutes, and to a smaller extent the hamstrings, which translates into more force available to drive the pedal downward with each stroke. “It becomes more of a running-like position,” he says of how the large muscles of the upper legs drive the rider forward. “It’s more efficient in a non-drafting situation.”
Because triathletes can’t legally draft in races, which is the more efficient way of cycling and is legal in road races, “we want to be able to get sustained power,” Hughes explained. By lowering the upper body into the aerobars and shifting the weight of the rider forward, that position “is kind of like riding behind three people. It’s a savings of about 30%” in energy expenditure, he says.
The design also helps athletes save energy for the run ahead. “The more we can put the body into 90-degree angles, the more bone it uses” rather than muscle energy, Hughes explained. By lengthening the torso, stacking the elbows under the shoulders, and resting the weight of the upper body into the aerobars, it alleviates pressure and strain on the muscles of the upper body and back.
“Your heart rate is going to do down because there’s no muscle holding the upper body up,” he explains. “I want about 70% of the pressure on my elbow, which will give me about 30% on the saddle,” alleviating pressure on the tailbone and freeing the legs to hammer hard.
Beyond simply making the rider more aerodynamic, tri bikes themselves are also increasingly tooled to be as efficient when cutting through the air as possible. “The frames are a lot more aerodynamic than road bikes typically,” says Hughes, likening them to how an airplane wing is designed. The idea is to make the parts that are facing the wind narrower, while allowing the air to smoothly move around them for less turbulence and resistance.
Even the placement of feeds on the bike are subject to this emphasis on reducing drag, says Hughes, noting that “the old school way we used to carry feeds was to tape them all over the frame.” These days, some tri bikes come with a slender rubber pouch that’s attached to the top tube where it’s within easy reach for a snack on the go, but not creating much if any additional resistance against the wind.
The Iterative Design of the Tri Bike
In refining the earliest designs, Empfield and his team at QR did not rely on fancy wind tunnel experiments. Instead, what limited formal testing they did was centered around ensuring that the bikes wouldn’t break.
Later on as the bikes developed more, (Empfield sold QR to Saucony in 1995 but remained head of the bike division for another four years) they did add some wind testing as talented riders like Lance Armstrong and Ken Glah arrived on the scene. But Empfield says “we didn’t test our bikes in the wind tunnel in order to validate their utility. That was beside the point for us. We knew how riders were going to ride our bikes. We knew what positions riders were going to strike aboard their bikes. Our interest was simply in making a bike that handled well.”
The best way to handle that was to simply go out and ride. Quintana Roo would build bikes, test them in the field, and then give them to their pros to ride. “We would just ask them how they felt the bike handed under all the various conditions. We did that much more often than attempting to quantify speed differences. How our frame compared to another frame in the wind tunnels was just of no interest to us.”
However, as the market for triathlon bikes exploded in the early 2000s with the arrival of new companies like Cervélo, Quintana Roo was forced to take another look at the aerodynamics of their frames. Now with plenty of competitors in the market making bikes that Empfield calls “technical marvels,” brands have had to find any advantage they can to stand out. “If I was still making tri bikes today, I’d be in trouble,” says Empfield.
Still, Empfield says there’s innovation yet to come in the design of the perfect triathlon bike. Two examples stand out he says, pointing to newer designs that have emerged recently from Specialized, CADEX, and Kú Cycle, which all featured “very wide fork blades and wide chain stays and seat stays.”
Design choice was interesting to Empfield because he’d seen something like it in the 1990s during one of his infrequent visits to a wind tunnel at Texas A&M. “A builder from Seattle named Dan Wynn put the strangest looking fork you’d ever seen on a bike. It was three arms of a rectangle. The fork blades were completely vertical, meaning they were spaced 100 millimeters at the dropouts and they remained spaced at 100 millimeters apart at the top. It was made out of steel and tested as well or better than any fork we had in the wind tunnel that day, including some really exotic forks,” he recalled.
That design made sense to him back then, and it still makes sense today and could lead to future design innovations. “The thesis was not dissimilar to what you might see in a biplane,” he explained, “where you have two wings that need to be a fair distance apart from each other to inoculate the plane from inter-reference drag. Each wing has its own aerodynamic construct so the airflow over the one wing doesn’t interfere with the airflow over the other one.”
It’s a similar situation when the front of the bike meets wind resistance. “If you have three aerodynamic constructs at the front of the bike—the left and right fork blades and the wheel—then you don’t have the fork blades and the wheel creating a kind of dam that the air has to make its way around.” Simply put, this rectangular fork design gives air a place to scoot through rather than around.
Empfield says that he doesn’t know whether it’s the fastest way to make a bike, as “it hasn’t been fully investigated yet, but I’m intrigued to see where it takes us. It’s a pretty weird-looking way to make a bike and three companies are doing it. I’ve always wondered from 1990s when what we saw then would make its way into bike deigns.”
Another area for potential innovation he sees deals with the “center of pressure at the front of the bike.” That is, everything that attaches to the steering column including the fork, the front wheel, the handlebars, and to some degree the rider.
Changing the amount of surface area behind the steering access could make for a more stable ride. “For example, if you make a fork that has a lot of surface area behind the brake line, you could theoretically neutralize the torque the rider feels when a side wind hits the deep sections of the front wheel occurs,” says Empfield.
This can help make the rider faster simply because it makes them more confident, which goes back to his original idea behind the tri bike in the first place. “I wasn’t trying to make a new position. I wasn’t trying to make a more aerodynamic bike frame. I was trying to allow the rider to ride in an aerodynamic, comfortable, powerful position with more confidence and better handling.”
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Finding Your Fit on a Tri Bike
Hughes, who competed as a pro triathlete in the late 1990s and early 2000, got into bike fitting when working at a bike shop in the late 1990s. He trained under Empfield’s F.I.S.T. (Fit Institute Slowtwitch) fitting protocol and still fits dozens of athletes each season at FastSplits in West Newton.
Over the two decades Hughes has been helping athletes find their best bike, he’s learned that it all comes back to physics and geometry. “As a bike fitter, I care about three points,” says Hughes. “I care about your feet, so your shoe-pedal interface. I care about your seat. And I care about your bars. Those three interaction points are important” to get lined up just right to provide an optimal fit.
“If any of those three points are wrong, then it’s all wrong,” he says. The frame itself is a secondary consideration that should be selected after the measurements for those set pressure points have been determined.
If you’re new to triathlon and thinking about getting a tri bike, Hughes recommended starting out with a road bike first. As you get deeper into the sport, you can add aerobars to that road bike. It’s no secret that tri bikes are a pricey bit of kit, running anywhere from $2,000 to more than $12,000 depending on the model and frills. It’s best to be sure you’re really into triathlon before sinking that kind of money into this high-tech piece of equipment.
He also says you should think about what your goals are and the distances you’ll be racing before taking the plunge on a tri bike. “If I was going to do a half-Ironman and I’d been doing the sport for a little bit already, then yeah, a tri bike might be a viable option because it’s more efficient. It’s a long run after the bike, so I want to save as much energy as I can.”
For races shorter than a half-iron/70.3, Hughes says most triathletes don’t really need a full-fledged tri bike. Unless you’re aiming to win the race or are trying to qualify for a championship, the time savings you’d get from a tri bike over a shorter distance may not be worth the extra cash outlay.
When you decide it is time for a tri bike, it’s imperative that you get fit properly. There are apps and remote options, but Hughes says it’s best to visit a professional bike fitter who specializes in fitting triathlon bikes in person. Hughes noted that “not every shop is triathlon-friendly,” so be sure to seek out one that really caters to triathletes specifically.
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