Specialized has been using its wind tunnel to answer burning questions about cheating the wind — in this edition they pitted road disc brakes against calipers. Using two near identical Tarmac frames, the only differences being the brakes, hoods and rims, they tested them at zero and ten degree yaw angles.
The guys at Specialized found there was no detectable aerodynamic difference over 40km into a head wind. As expected, at a 10 degree yaw angle the discs were a bit slower, eight seconds over 40km infact. We did spot that the front rim brake cam was left open during the test, so it would be interesting to know if this had any affect on the result.
Apparently #aeroisNOTeverything – as Chris Yu points out that on a winding course, those eight seconds would be easily made up on a descent and through corners with the braking advantage given from disc brakes.
For the test specalized used both the standard and disc versions of its tarmac frame:Courtesy
We recently tested the Specialized S-Works Tarmac Di2 Disc and found it to be an incredibly confident and capable machine. However, despite disc brakes on road bikes offering improved braking performance, potentially lighter wheels, lower maintenance and minimal aero disadvantage, the market is still awaiting an agreed axle standard.