Editor’s Note: In April 2011, we unveiled VeloLab, our in-depth bike and component testing program that combines objective, lab-based metrics with on-the-road evaluation. In the 18 months since, we’ve tested more than 25 bikes, from sub-$1500 budget road racers to the bikes of the WorldTour. The following cover story first appeared in our August 2012 issue and pits two top time trial bikes against each other: the Trek Speed Concept 9.5 and the Specialized Shiv TT.
A look at the fastest human-powered machines on two wheels
With 101.4 kilometers of time trialing in this year’s Tour de France, the bikes ridden in the race of truth will be more important to the general classification contenders than in recent years.
The amount of time and money that big teams and their associated sponsors invest in making their riders faster against the clock is significant. Rider position and appropriate wheel choice have a considerable impact on the speed equation, but the frame and fork (or module in the case of some) determine how easily a rider can achieve his ideal position. With that in mind, the VeloLab set out to see who might have an advantage before the clock even starts.
Both Trek and Specialized took part in our test. We had hoped to test Cervélo’s new P5 and BMC’s time machine, but neither was available in time for testing in the wind tunnel or on the road.
We sent both bikes and a control set of wheels (a Rolf TdF60 front and a Zipp Sub9 disc rear with 21mm Vittoria Corsa CX tubulars) to the A2 Wind Tunnel in Mooresville, North Carolina, to see how they stacked up against the wind. Both bikes were set to the same position and then the saddles were removed. No pedals or bottle cages were installed.
After that, both Caley Fretz and Nick Legan channeled their inner Miguel Indurain and took to the roads of Boulder, Colorado, to see how the bikes handled and how easily they could find their preferred positions. Here’s what they found.
From the side, the Speed Concept appears to break fundamental aerodynamic rules.
It looks neither sleek nor smooth; gone are the teardrop-shaped tubes and ultra narrow profiles, replaced with blocky, square-tailed forms that seem anything but aero.
Turn to the front though, and view the frame as the wind does, and the Speed Concept is a masterpiece. It cuts a slim figure and boasts one of the cleanest front ends in the industry, with a fully integrated front brake and slick cable routing.
The UCI’s 3:1 rule, article 1.3.024, states that, “a fuselage form shall be defined as an extension or streamlining of a section. This shall be tolerated as long as the ratio between the length and the diameter does not exceed 3.” Those blocky trailing edges are known as Kamm tails, cut-off profiles with carefully tailored edges designed to make a UCI compliant tube perform like it is much longer and narrower than it actually is. The UCI also stipulates that all main tubes must be at least 2.5cm in diameter. With the Kamm tails, you get low drag figures into a headwind and even better performance in crosswinds.