I've just gotten into cycling in the past year or so and gotten into the sport of cycling too.
Obviously the benefit of drafting in the peleton is massive and can, apparently, save up to 30-40% of energy. What I'm curious to know is what is the benefit to us mere mortals cycling along the road at a lesser speed with fewer friends.
I commute around 15 miles each way along the roads of Glasgow. Average speed around 17mph but along the straight even roads (where you can find them) I average around 20mph. When I take the wheel of a fellow commuter or vice versa, what would be the net benefit at that speed in terms of energy saved?
There are good benefits to be had, I'd say 15% at that type of speed, perhaps more. It helps if you can optimize the draft by riding not directly behind the "engine" but in line with the wind, if the wind is coming from ahead. Sometimes the engine has to move over a bit to the right so that you can fit in the "gutter" and sometimes the engine has to move over as far towards the gutter as possible to give you space on the right. It is a co-operative exercise and well worth discussing and practicing regularly. It makes very long rides shorter and really hones your skills.
Obviously you have to share the burden and switching around requires special skill. The engine always falls back and the next person in line simply keeps the speed absolutely constant even though he/she now has to pedal harder to fight the wind. The crucial part is constant speed. Do NOT suddenly jump and think that you are Tarzan/Jane now that you are in front. That causes a concertina ripple behind you that saps energy. The engine peels off and falls back and falls in line. The engine must not pull for hours at end because it is hard work at the back in concentration currency at the back too. The engine should pull for 30-40 seconds and then pull back so that the rotation is constant and smooth. If there are three or more riders in the paceline, then the engine only pulls for 5 or ten seconds before pulling back. Then you'll find that the line of riders pulling back will equal the line of riders going forward and you'll have a rotating circle of two-abreast cyclist travelling fluidly along the road with minimum energy expiration.
Drafting is fun, rewarding and sometimes even awesome, if I dare use that word. The most exciting paceline of them all is one where two circles of cyclists ride four abreast going at one hell of a speed that's too fast for a single person to maintain for more than a few seconds, yet the entire unit moves like a flash. Inside the pack it is silent except for chain and tyre noises. At the front the wind roars.
Good etiquette in a paceline is to watch where your snot rockets go, not to sweat on people behind you (you squeeze your helmet out when you are at the back) not to jump when you take lead, not to twitch when in the bunch, to fluidly stand up on hills from a seated position so that you don't change speed at all (this requires plenty of practice) and not to touch your brakes if they make the slightest noise as it scares the hell out of the rest of the pack.
Happy drafting. It is great.