A cyclist saves energy by staying in the slipstream of the rider in front. But does the rider in front expend more energy than a solo rider travelling at the same speed?
Paul Haydon
Watchfield, Oxfordshire, UK
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I am 69 years old. As a teenager, I was a keen cycle racer. When I was 18, I rode 17 road races, with 14 top six finishes (and two visits to hospital!). Later in life, I was a keen tandem cyclist with my wife. I also studied fluid mechanics and aerodynamics at university.
If you look at one cyclist going hard into a headwind, there is a high-pressure area in front of them, which pushes them back, and low pressure behind them, which pulls them back. If a second cyclist joins in behind our leader, the low-pressure area is partially filled, hence the leader has less wind resistance as a pair.
This is most noticeable when riding a tandem. We used to ride orienteering events on our tandem. On the road sections, into a headwind, we would scorch past solo riders.
In the Tour de France, when there is a solo time trial, the riders are followed by a team car with spare wheels and bikes on top. The cars must stay at least 50 metres behind the rider, so as not to assist.
David Muir
Edinburgh, UK
When a cyclist moves, turbulence is produced in the form of vortices, eddies of air behind them. This causes low-pressure areas, creating drag, a force that slows cyclists and against which they must pedal harder to maintain speed. If a second cyclist moves into the space directly behind the first, the low-pressure area will pull the second cyclist along because the air in the vortices rotates from the outside in, and this movement pushes the second cyclist.
Cyclists call this drafting and, counterintuitively, it benefits the first cyclist as well as the second. By occupying the space behind the first cyclist, the second cyclist cuts the first’s drag. The first cyclist still needs to work harder than the second, but not as hard as if they were cycling on their own.
Cyclists in a race form a pack called a peloton, where everyone except the lead cyclist benefits from riding in someone else’s slipstream. A cyclist in the peloton can use up to around 50 per cent less energy than a cyclist alone.
Things get more interesting if there is a crosswind. Rather than ride in a peloton, cyclists will ride in an echelon, a diagonal line of cyclists, where the lead rider fights the wind, let’s say coming from the front and to the right. The second rider will cycle behind and to the left, in the lee of the lead cyclist. When it is time to change the lead cyclist, the front rider peels off to the right and moves back round the echelon to attach to the rear.
David Fishel
Indianapolis, Indiana, US
As a former competitive cyclist, as my several healed fractures attest, I was intrigued by this question.
According to ““, published in the Journal of Wind Engineering and Industrial Aerodynamics in 2018, the answer is the lead rider actually benefits as compared with if they were riding solo.
The reason: the following riders, by keeping close to the leader’s rear wheel, reduce the rearward sucking effect produced by a low-pressure area that naturally follows the leader. According to the paper, this can generate a 4 per cent or more advantage. Also, the configuration of the peloton can make a difference too, e.g. a single line or a diamond-shaped arrangement consisting of many riders, spread out across the road.
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