More watts indoors= more speed outdoors?


#1

Just curious to know if your FTP was 200watts and in 6 weeks you had a 10% increase to 220watts does that also mean a similar gain in your speed outdoors?


#2

To oversimplify, yes. You will go faster.

However, you will not be 10% faster because the nature of wind resistance, road grade, power production and such are non-linear relationships. So, don’t expect that a 10% increase in FTP means you will increase from 20 mph avg to 22 mph avg. The end result is far from simple like that.


#3

To add to Chad’s answer, wind resistance increases with the CUBE of your speed. Going twice as fast requires 8 times the watts to overcome air resistance.

On a steep hills, 10% more watts will give you close to 10% more speed, but on the flats you can expect only a slight increase in speed.


#4

Loosely yes but pacing (where you apply that power) in addition to drag, wind, rolling resistance etc will determine your speed change.


#5

Interesting… seems about right since I’ve gained a lot of watts, but my strava segment improvements can be measured in 10-15 s blocks at a time, but when I get on my mountain bike, I can sometimes crush my old PR by a minute or more.