Drafting question - more speed at same wattage or merely makes it easier to achieve a level of wattage?

Please point me in the right direction, or please help me answer my question or start a discussion on it.


I haven’t been able to find Zwift’s specific logic behind its drafting algorithms.

  1. As my title states - when we are drafting, do we get to go faster while pedaling the same amount of power? For example, if I pedal 150w on 0%, let’s say I go 25kph. If I pedal 150w on 0% while drafting, I’d go 30kph.


  1. While I’m drafting, Zwift makes it easier to pedal 150w, where my real pedaling would be about 120w if I wasn’t drafting.

Surely this is answered somewhere, but I cannot find it. #1 would make more sense and mimic real world situations, however, I’m not sure that’s actually happening.



To add on, it’ll say I’m at 200w when I know I’m pedaling about 160w when I’m drafting behind.


It shouldn’t be this way. If I’m pedaling 160w, it should say 160w however, and then let me go at whatever speed I’d be going due to the draft benefit!


You’ll go faster at same wattage (1). However, your speed is based on the rider you are drafting. If you were drafting your identical twin who was doing 25 kph at 150 watts, you’ll simply ride beside him. You need to draft a rider at a speed of at least 26 kph.

It is all about your w/kg. (ex. 150 watts at 75 kg = 2 w/kg)

I can draft riders 4.5 w/kg when I’m doing 4.0 w/kg. If they are doing 5.0 w/kg, I can only do the needed 4.5 w//kg to stay on their draft for a short time, not the entire race. When they hit 8, I can’t hold on at all, even briefly.

It’s not really about w/kg at all, as that’s irrelevant on flat routes where the draft is most effective. 

It simply allows you do to more speed for the same watts or to use less watts for the same speed - which is the same thing.

What it doesn’t do is increase or decrease the resistance on smart trainers - that’s only for slopes.

I should have been more specific. It has everything to do with w/kg, but the w/kg of the rider you are drafting is what determines speed. If your w/kg are too low, you won’t hold the draft.

but to be clear, it is about w/kg, even if it is estimated z-power wattage.

I did notice that if you catch up with someone with let’s say 200W. and you start drafting, your power stays the same. You will not overtake him. But you can reduce your power to e.g. 170W and still stay drafting. So, you can keep the same speed and reduce your power.