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. We’ve even given four commuter rigs a spin and tested a run of seatposts for vibration. In our November issue, Lennard Zinn puts five different tubular tires through the paces in Finland to determine the effects of tire size and air pressure on rolling resistance. The following cover story first appeared in our May 2012 issue and pits four aero road bikes against each other: the Cervélo S5, the Scott Foil, the Specialized Venge and the Litespeed C1.
Aero revisited: One year on, how far have aero road bikes come?
A decade ago the aero road bike segment didn’t exist; today it is redefining how race bikes are made. Ten years after Cervélo led the way with its aluminum Soloist, Specialized, Felt, Scott, Litespeed, Ridley, Blue and others are fighting to make race bikes that best their round-tubed competitors. In the past, significant aerodynamic gains came at the cost of frame stiffness, which explains why many racers preferred round-tube
bikes. But what do the aero bikes of 2012 have to offer?
In our second round of aero road bike testing (For our first test, see Velo April 2011) we once again made use of the independent test facilities at the A2 Wind Tunnel and Microbac Laboratories, Inc., ensuring objective testing of aerodynamics and torsional stiffness.
For the wind tunnel, we prepped each bike by setting a standardized bar height and cutting off the excess steerer tube. We ran cables as short as possible on each of the bikes while remaining operable for daily use. We removed the saddles (something the wind rarely sees) and made sure the same amount of seatpost was left exposed on each bike (measured saddle rail clamp to bottom bracket center). Gear selection and crankarm position were also carefully set and locked in place. Lastly, we used the same set of wheels for each test, a pair of Enve Smart 6.7s with 23mm Vittoria Corsa CX tubulars inflated to 100 psi. No water bottle cages were installed, nor were pedals or any other accessories.
To test torsional stiffness, Microbac replicated our earlier tests, which measure frame deflection at three locations under load. For more detailed information on that test, see page 84.