Freedom of tailwinds

As a habitual cyclist there are factors that make cycling difficult and factors that make it easy.  The number one thing that slows or speeds up a rider is wind.  Wind is air, moving air and most people do not understand how critical wind is on bicycle speed.  They say it is a factor, but they don't get it.  When you are walking or running the wind has to be really blowing to be a factor.  When you are swimming a current does not have to be that large to be a factor, but water is nearly a thousand times the density of air, so people don't really get it.  

A ten kilometer wind is a big thing, twenty is huge and forty is gigantic.  It is because wind resistance is the biggest factor after road conditions on a cyclists' speed.  Think about it, if I top out at 50kph on a flat surface and the wind is in my face, the wind would be going its speed plus my speed and if I am limited to 50kph wind resistance that would mean at 10kph wind velocity I would be going 40; at 20 kph wind, I would be going 30; at 40 kph wind I would be going 10 relative to the ground, but 50 kph relative to the air.

It is not a one to one relationship in speed as it is easier to go 10 kph than it is to go 20, but a head wind really slows you down.

A tail wind does the reverse, again it does not add to you speed but makes it easier to go faster and your upper speed limit is faster too.  

Today I had a great ride.  I was going fast and I was a strong rider.  I was zipping past other cyclists and I was speeding beside cars, at one point I was even passing cars on flat road.  I did not realize it but I had a twenty kilometer tail wind, when I stopped it was enough to cool me down, but when I was cycling I had more energy and I could go faster.  I went faster; I felt freer.