Imagine for the moment that you are cycling along a straight, but undulating track or road.

You have a 20mph tailwind.

Is it more efficient (from a riders energy pov) to maintain 20mph along the flat and save your effort for the climbs, or to take advantage of the tailwind on the flats to go even faster but then be more tired when it comes to the climbs?

It is always best to expend extra energy when you are moving slowly, as air resistance to acceleration is lower at lower speeds. So, work harder on the climbs and easier on the flat and descents.

Well… not sure.

Maintaining a constant power output is better, your muscles will tire less if you don’t go into the red. But you won’t get as much of a training benefit.

So I’d take the second option probably if I wanted to be efficient. If you pedal as hard as you would normally, you’ll go very very quickly indeed, ime.

It is always best to expend extra energy when you are moving slowly, as air resistance to acceleration is lower at lower speeds. So, work harder on the climbs and easier on the flat and descents.

This. I’ve read several cycle training books now which say the same. Save your energy for the climbs, as the efficiency to speed ratio gain is much higher. The way I work it is to turn a higher gear in the tailwind and keep my legs turning at an effort where I can’t “feel” my legs being strained (typically Z2 effort or and RPE of 3-4 for me)which allows me to sail along at 40+ kph with minimised energy loss.

That assumes the contribution to overall fatigue is proportional to effort. It’s not.

bet you there is some psychological advantage though to powering up on the flats so the momentum helps you into the next hill.

Keep your peak speed low, and your average speed high. Air resistance goes up in proportion to the square of your speed.

LabMonkey – Member
It is always best to expend extra energy when you are moving slowly, as air resistance to acceleration is lower at lower speeds. So, work harder on the climbs and easier on the flat and descents.

This is absolutely correct in terms of required power output.
Although, as mentioned above, energy expended for the same average power may (will) not be the same for constant output vs multiple easy/hard sections, since your body isn’t equally efficient at all power output levels.

I guess as long as you don’t totally kill yourself on climbs and stay fully aerobic, then more effort on climbs where you aren’t wasting energy against air resistance would be the most efficient method.

If by efficient, you mean faster, then labmonkey’s way is best.

powering up on the flats so the momentum helps you into the next hill.

A potential complicating factor, but probably only really significant on very small hills.

Depends on your route too. If it’s long flat stretches with a tailwind, then whatever you do on the flats will have more bearing on your average speed, won’t it?

Depends if im riding on my own or with a group. If its a group and i know they are silly fast on the climbs, i save my energy for the climb. If i’m on my own and don’t care about speed on the climb, i’ll take advantage of the tailwind.

Go fast with the tailwind, gel before the climb, sorted?