So can tri bikes perform on every type of course? Or are there times to bring out the trusty road bike?
Given the specific job a triathlon bike has to do, how much of a difference can one make compared to a normal road bike with or without aerobars?
“For the same rider [whose body and position is the cause of the largest proportion of the total drag] on all three bikes, a road bike without aerobars can generate as much as 20–25% more drag,” says Trek’s Carl Matson. “[That] sounds like a huge number and it is. Even if you can stay down in the drops for the entire ride, you’re presenting more frontal area and non-aero shapes to the wind due to the wide arm position.”
Clip-on aerobars will help to reduce that number, but even with them it’s still difficult to reproduce a triathlon bike’s riding position without a forward-angled seatpost and non-standard stem.
“[Assuming] a rider can achieve the same position on a road bike with clip-on aerobars as they can on a tri bike,” continues Matson, “any remaining aerodynamic differences would be down to the bikes themselves. In this context, a tri bike’s advantage would be reduced but if the rider’s on a Trek Speed Concept, they’ll be producing 3–5% less drag.”
Whether those figures come from real-world testing or the controlled conditions of a wind tunnel, they make a convincing argument for using a triathlon bike, especially in long-distance races where efficiency is a greater priority than sheer power. But the specific nature of their design also makes them ill-suited in certain situations, such as races with hilly or technical bike courses.
Weight and winds
Triathlon bikes fail to shine on such courses because the extra material required to make them aerodynamic adds weight, and their ‘pitched forwards’ riding position leads to awkward handling.
Furthermore, all the extra components that make up a tri bike’s cockpit reduce the clearance for your knees and wrists when you want to get out of the saddle to climb or accelerate.
But what about crosswinds? All those broad tubes look ripe for getting shoved around and making your life difficult in side winds. Well, yes, up to a point. Because, depending on the strength and direction of the wind and the shape and dimensions of the tubes, crosswinds can actually help.
“Just like a disc wheel can be really good in crosswinds, the increase in surface area and very smooth, very controlled shapes end up helping the bike get pushed forward in a crosswind,” says Specialized’s aerodynamics R&D manager Mark Cote.
“Yes, [more] side surface area can push you over, but if you have the surface area in the right place it actually makes the bike ride more stably… [the bike] ends up effectively sailing by taking energy out of a crosswind to push you forward.”
It’s a safe bet that tri bike designers will continue to focus on aerodynamics as they search for ways to improve their machines in the future. But that’s not to say there aren’t other elements under consideration, as Carl Matson explains.
“At the high levels of the sport, I see the industry trending towards more integration of components, features and accessories. More system-level solutions as opposed to the ‘à la carte’ aero market we have right now.”
In other words, we’ll see more bikes with the sort of dedicated bars, bottles, boxes and brakes that can be seen on a host of tri bikes, including the Trek Speed Concept, Scott Plasma, Felt IA and Cervélo P5.
Brakes, in particular, are a hot topic, given the arrival of disc brakes on consumer road bikes and their imminent trial in pro road racing. So are they an option for triathlon in the future?
“They’re a worthwhile option in triathlon right now if you’re doing Xterra,” says Matson of Trek. “Otherwise, I see disc brakes on triathlon bikes as something that only happens on a large scale if and when the road bike industry achieves a major changeover to the technology.
“The dedicated triathlon bike appeals to athletes who, for the most part, are looking for every speed advantage or power saving they can find. [Having] something extra hanging out in the wind costing them watts when it’s not being used has a hard time justifying itself.
"On that basis alone it wouldn’t surprise me to see highly-integrated rim brakes survive a disc brake revolution as a performance advantage. And that’s without considering the improvements in rim brake performance hydraulics might bring.”
Although we might not be saying goodbye to the rim brake just yet, with ever more integrated ‘hydration systems’ appearing, the same might not be true for the traditional drinks bottle.
(Images: thesecretstudio.net / Michael Rauschendorfer)
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