The spectacle that is the Tour de France (TdF) is all about aerodynamics - and you thought it was all about the bike. Virtually all tactics in the TdF are dictated by individuals or teams of riders attempting to limit their exposure to the 'wind', in order to minimize drag and therefore minimize the effort required to progress. There are some obvious and not so obvious tactics riders and teams employ to use aerodynamics to gain advantage.

Please don't try this at home 🙈 #safetyfirst #TDF2016 #TDF pic.twitter.com/Vns5QW1cFY

— Chris Froome (@chrisfroome) July 10, 2016

Position

A rider's position on a bike is the primary cause of wind resistance, which by most estimates is about 80% of the total drag for the rider and bicycle combined. This is why riders go to great contortional lengths to get as low as possible on the bike, whether it is a road bike or a time trial bike.

The Perfect Tuck

The latest craze is to sit on the top tube rather than the saddle for high speed descents in order to present as small a cross-section to the wind as possible.

Drafting

Riders prefer to draft behind other riders to reduce the effort required to sustain their speed. The following rider can experience up to a 45% reduction in drag relative to the rider leading the charge into the wind. Often you will see riders drafting behind cars in the TdF after a mechanical incident to minimize the rider's effort to rejoin the peloton. Motorbikes too serve as a great lead out for a rider launching an attack, by punching a hole in the air as the rider accelerates.

Drafting

Echelons

In cross winds the riders align themselves in so-called echelons that form a diagonal line across the road. The challenge with echelons is that the benefit of the draft only extends for the width of the road. Anyone wanting to benefit from this form of draft has to be on the diagonal. Riders unlucky enough to be off the diagonal and riding at the edge of the road (therefore facing a component of the wind) typically on the tail of an echelon will find it increasing difficult to stay in contact.

Echelons

Pursuit Vehicles

During individual time trials, not only does each rider have a special time trial bike optimized for a low drag body position, but they also have a team pursuit vehicle behind them. The closer the pursuit vehicle is to the rider the lower the drag force on the rider. In theory there is a rule governing this proximity, but in practice it is difficult to enforce.