When a cyclist rides he creates vortices behind him, these vortices create a small area of lower pressure. The combination of this low pressure and the eddies can suck a cyclist that is behind forward. Being situated behind a cyclist close enough to take advantage of this effect is called drafting. Drafting is synonymous with slipstreaming, with the area of low pressure call the slipstream.
Drafting also works co-operatively (ever seen birds flying in a v-formation), any rider behind the second rider will also benefit from drafting as well as cyclists that are behind him. Cyclists that are behind and offset to the side (such as in the flying-v formation) will also benefit.
The Draft:
You can save up to 40% of your energy by drafting. The draft not only benefits riders behind but the front rider will also gain a small advantage, however this is much smaller than the riders behind gain from drafting. In a long line of riders, the second rider gains about 25% draft advantage whilst all the riders behind him gain around 35% draft advantage. In a middle of a pack, such as a peloton (the name given to a pack of cyclists like in professional bike races) you can use up to 60% less energy.
Moving closer to the rider infront will increase the drafting effect, more drag closer, less drag further away. There is still a small slipstream when 4 metres away for the rider infront.
The draft is significantly reduced when the bikes are moving faster, so there is less to gain from draft on climbs and more to gain on the faster flats and downhills. Sitting in a slipstream also protects you from the wind, the drafting effect is greatly increase when riding into the wind.
- Sit behind the rider you want to draft behind, sit slightly offset to the side so that if the rider in front suddenly slows your wheels will not make contact.
- Do not cross wheels (this is where accidents happens), if you make contact its usually the rider behind that is worse off (because the front wheel can move more with handlebars).
- Look ahead, don't stare at the wheel in front. You want to see obstacles coming well before you meet them, such as a turn or incline so you can predict what will happen. Get used to gauging the distance from the rider infront by looking just over his shoulder.
- If you are riding in a group, no twitchy movements, its the easiest way to cause an accident, moving slowly will help the riders around predict where you are moving too.
- When a tight corner is approaching, easy off, allow a gap to form with the rider infront. When you start coming out of the corner, you can put the hammer down and if you have timed it right (takes practise) you will catch up with the slipstream infront as you pull out of the last part of the corner. You will corner most efficiently this way, saving energy. If riders don't ease off, the paceline or pack of riders can bottle up at the entrance to the corner, wasting energy and causing accidents in some situations.
- After you have taken your pull on the front, and are coasting back down the paceline, start applying pressure just as your front wheel is next to the last cyclist rear wheel, so you can fit in snug behind. If a gap forms between you and the paceline, believe me it can be hard work joining back up, if you don't make it, this is what getting 'dropped' means.
- When on the front, make sure you signal well. Point to the road on the side of any approaching hazards or potholes. When you are going to turn signal by stretching your arm out to the side straight in the direction you will turn to. When you are going to be braking, wave your hand in a backwards motion. If needs be shout! signalling and shouting will keep the riders behind well informed on what going on. to signal that you have finished your turn on the front (or simply had enough), flick your elbow to the side you will swing to and give a few last hard pedal strokes.
Pacelines, Pelotons and Echelons:
There are four main types of drafting formation in cycling.
- Paceline: is simply a line of riders drafting one behind the other, works best for small groups and training rides, offers no protection from cross winds.
- Chaingang or two-line: is a group of riders orientated in two pacelines next to each other. works best for medium sized groups. the lead rider when he has finished his pull at the front moves off to the side that is into the wind. The first paceline is moving forward and riders are breaking off to the second paceline and the riders in the second are moving slowly backward and rejoining the first paceline.
- Peloton: a huge group of riders, seen mostly in professional races. riders in the middle of the peloton are completely protected, crashes are common and riders need to be alert for hazards approaching as there is little visibility.
- Echelon: the name given to a shape of a group of riders, that is most efficient in high winds (a paceline for crosswinds). like a chaingang there is two lines, but orientated diagonally moving forwards, the diagonal axis is pointing into the wind. Only as wide as the road, riders that cannot fit into the echelon have no protection from the wind, its a very tactical formation in road races. riders falling off the back are said to be in the 'gutter', and trust me this is not a very nice place to be, hard work! the riders move up the line in the back of the echelon and down the line on the front of the echelon.
Tip:
you can feel the draft when you are in it, it feels warmer than being in the open. You can use the feeling of wind on your shoulders to work out where the best draft is. for example if you feel more wind on your right shoulder, move slightly more to the left.
being in the draft not only gives you an energy advantage, but it gives you the advantage of being able to watch your opponent. you can watch his gears and movements to predict when he is about to make a move.
watch objects in your surroundings to see where the wind is blowing, eg trees swaying. You can use them to judge where you should be drafting, if crosswinds are approaching or if their will more advantage drafting or pulling at the front.
Unfortunately most triathlons are not 'draft-legal', this means you cannot draft. stay within the distances mentioned in the race rules (usually a 3m by 7m box surrounding the cyclist infront is the no go zone).
Also be aware that TT bikes are less manoeuvrable than normal road bike, so drafting with these extra care should be taken. not only that but people with aerobars, may not be able to reach the brakes in front. (its never really a good idea to draft with a TT bike, you should be suing them for time-trials anyway!)
Why mention it then? great for in training, and a useful skill when going on group rides, every cyclist should know the basics of drafting.
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