Most people already know that aerodynamics are important in an individual event – a TT or solo breakaway, for example. Some people don’t think aero matters when riding in a group. They’ll say: I’m drafting, aero doesn’t matter to me. However, even in a group, most of the retarding force you’re pedaling against is still aero drag.
Asker Jeukendrup (High-Performance Cycling, 2002) measured a 30% decrease in power required while drafting, compared to riding alone. This roughly matches the drag savings we’ve measured on the road with our on-bike instrumentation. This decrease is due only to the reduction in aero drag when drafting, as nothing else changes: mechanical friction and rolling resistance are unaffected by drafting.
Most drag-yaw charts are taken from wind tunnel test data for a single bike, not drafting. This data is usually the source for the most commonly cited drag savings. So when you’re in a group, discount the drag savings by about 30%. For example, when we say the Cervélo S5 saves 9 Watts compared to the S3 when riding alone, it means you’ll save about 6 Watts when drafting in a group.
Remember this savings is in addition to the power saved by drafting in the first place. By sitting in the group, you already save 30% – after all, that’s why we draft (we discuss this in our aero article found here). For example, if you already save 90 Watts by drafting, you can save 96 Watts by riding an S5. You save 6 MORE Watts.
Team Garmin-Sharp sports scientist Robby Ketchell recognizes this advantage, and the team riders have their choice of Cervélo models.
David Millar, eventual winner of stage 13, 2012 Tour de France
For example, David Millar won stage 12 in the longest stage of the 2012 Tour de France on his S5 Team, in a sprint among the survivors of a small breakaway group. Even though there was lots of drafting, the energy David saved by riding his S5 all day (and the days before) might have made the difference he needed to win the sprint!
David Zabriskie - Tour de France 2012, stage 12
Nathan Haas, Robbie Hunter - Tour Down Under, stage 4
Other Garmin-Sharp riders also choose the S5. At the Cervélo BrainBike event last autumn, South African national champion Robbie Hunter said he prefers his S5 for most races in his native country and European races as well. Dave Zabriskie, Alex Howes and Michel Kreder are also devotees of the S5.