HOW TO CALCULATE YOUR POWER-TOWEIGHT RATIO

POWER-TO-WEIGHT RATIO IS one of the most telling metrics in cycling - and thanks to indoor trainers, many more cyclists are now familiar with it. Right now it's never been easier to calculate your power-to-weight ratio and use it to improve your performance.

- MOLLY HURFORD

To help you get more familiar with this metric, let's dive into exactly what it means, how to calculate your power-to-weight ratio, and why it may (or may not) matter for your training.

WHAT IS POWER-TO-WEIGHT RATIO?

Power-to-weight ratio (PWR) is the amount of power you can produce in relation to your body weight. It's usually expressed in watts per kilogram (W/ kg). The higher your power-to-weight ratio, the faster you'll go. This is why the measurement is also a great predictor of cycling performance.

PWR allows us to compare cyclists' abilities even when the riders vary in size, which is why many refer to it as cycling's great equaliser. That's also why apps like Zwift use it to help figure out which group you'll be riding in when you join their virtual competitions.

If you're confused as to why weight comes into play, you're not alone. Power - the watts you put out on the bike - is objective, so why doesn't Zwift (and other platforms) just base the ride groups on that? Well, imagine you're a 55kg cyclist riding up a hill at 240 watts. Now, imagine a 110kg rider going up the same hill, at the same wattage. They'd be going more slowly, because it takes more energy to move a heavier body.

Because of this, PWR is used to compare the riders. In the example above, the 55kg cyclist has a PWR of 4.4W/kg. The 110kg rider has a PWR of 2.2W/kg. (To put that number in perspective, an athlete needs to be able to produce 6.8W/kg in a 20-minute pre-race test in order to have even a sniff at winning the Tour de France!)

On average, beginner racers range from 2.5 to 3.2W/kg for men and 2.1 to 2.8W/ kg for women. More serious amateurs typically range from 3.7 to 4.4 W/kg (men) and 3.2 to 3.8W/kg (women).

Zwift uses PWR to segment racers into categories ranging from A to D, with A being the most elite:

A = 4.0+ W/kg

B = 3.2-3.9 W/kg

C = 2.5-3.1 W/kg

D= 1-2.4 W/kg