Drafting is a way of conserving your energy by allowing a rider ahead of you to separate the wind while you stay in their slip stream. By doing this they say the second rider can use about 20% less energy to go the same speed.
I have read articles that say ‘don’t over-lap wheels’ and ‘don’t break’ when drafting, but when you are drafting properly you are at most about 6″ from the wheel in front of you. Now add in variations of effort, grade, and rider energy into the mix and there is no way that you can not either over-lap wheels or touch your brakes at some point!
Which of the 2 you do, I would suggest, is based on the rest of the group around you. In all situations you should first attempt to adjust how much pressure you are putting on the pedals to best adjust your speed. I will also use gearing to assist in this process. When I’m attempting not to brake I will spin an easier gear w/ higher cadence – when I’m going too fast, I first stop spinning as fast (but keep the legs turning when I can).
This was best learned at the velodrome where the bikes do not have brakes, only fixed gears (so no coasting). When you don’t have brakes on the bike you become very alert to your cadence and the ability to adjust your cadence based on how close you are to the rider ahead of you.
In a group of less experienced riders I would suggest NOT overlapping wheels! Less experienced riders tend to move side-to-side more than experienced riders. In this situation I would first try adjusting speed by not pedaling as fast, then if necessary by lightly feathering the brakes. As you get better your use of the brakes should become not as strong, just enough to add some drag.
Although it is the responsibility of each rider to not hit the rider ahead of them, it is also good to keep in mind that you have other’s well being in your hands based on your actions. No one is perfect, but there are some riders I will avoid or go around ASAP! Yet, there are some riders that I have no problem drafting behind them as long as possible.
When other riders are involved what can happen is that the whole or parts of the pack can do a paceline. A pace line is a way for the group to maintain a higher speed using Drafting, by alternating who gets to draft, while giving each rider a chance to recover from the brief effort of speed.
If you are in the paceline and you are having trouble keeping up the pace, it is OK to sit-on and take a break for awhile! When you are pushing beyond your limits is when fatigue sets in and accidents happen. And when pace-lining, your accident can involve several other people.
Remember the group is only as fast as it’s slowest member (weakest link). If the group is going too fast for a rider then that rider either will not be able to pull through very much or they can sit-on the pace-line.