Cycling Power: Why your numbers mean nothing to me

As the price of cycling power meters drops, they are obviously becoming much more socially prevalent. 

And as they fill our culture you also begin to hear everyone talking about their power numbers.

“I hit 800 watts on that climb!” 

“I was able to stay just under 275 watts the entire ride.”

While this may sound impressive (or unimpressive) to you, I want to take a moment and tell you why those numbers don’t matter and why you shouldn’t put too much weight into the fact your riding partner consistently rides 25 watts higher than you.

Gear

There are a lot of power meters out there and one of the issues is they all read a little bit differently. 

Your power numbers could change depending on if you are using pedals, crank, hub, or your smart trainer. And it’s not just the location.

Even pedals or a smart trainer from one company will read differently from the same “source” of a different company.

Not only that, but if a power meter hasn’t been appropriately calibrated, then you can get different power readings at the exact same effort before and after calibration.

The first thing to understand when comparing your power numbers to someone else’s is you can’t compare apples and oranges. And sometimes, you can’t even compare apples to apples if they aren’t from the same tree (i.e. smart trainers from different companies).

Weight (the ultimate reason)

Because this is the Triathlon Simplified blog, I’m not going to go too deep on this. But if you truly want to compare your power to someone else’s, the only actual way to do this is by calculating and comparing watts to weight. 

In cycling power, you’ll often see w/kg. This stands for watts per kilogram. Because ultimately we want to know how many watts it takes to move your body.

Storytime:

You recently did an FTP (functional threshold power, the highest power you can ride for one hour) test. Your FTP came out at 235w. You weigh 150lbs.

Your friend did the test and crushed you with a 305w FTP. He weighs 200lbs.

150lbs = 68kg. 235w / 68kg = 3.4w/kg

200lbs = 90kg. 305w / 90kg = 3.4w/kg

WHAT?! That’s right. Even though he tested at 70w higher you still have the exact same w/kg, and so on paper, you are just as strong of a cyclist. 

Now, this doesn’t take into account the weight of a bike on a climb, or how you may be significantly more confident bombing down a decent. 

But on a flat course, exact same gear, if you ride at 235w for an hour and your friend rides at 305w for an hour you’ll cover the exact same distance.

The reasons we aren’t diving deep into

A few other things to take into consideration…

If someone mentions they did an entire ride at “275w” a follow-up question would be, “Is that normalized power or average power”? In short, normalized power (NP) is like grading your power on a curve, removing the peaks and valleys.

When someone says they hit Zone 7 on a climb, have they actually done an FTP test or just using the defaults on their watch? Was their power meter calibrated? 

Even if someone tells you their w/kg, it’d be beneficial to know when their last test was and if they are at the same weight. If they’ve lost weight it could be higher, if they’ve gained weight it could be lower!

A higher w/kg doesn’t decide who the race winner will be. If that were the case, we’d just compare test results. Never discount tactics and riding skills. Sometimes it’s the better rider, not the stronger rider, who wins.

Ultimately, I want to encourage you.

First, when you hear people throw around watts as if they are dropping bombs, don’t be quick to assume you could never hit their watts. Because you could be at the same w/kg!

Second, don’t throw around unqualified watt numbers yourself. Sure if you want to throw in your w/kg for reference you can, but really, what does talking about your watt numbers do other than serve as a tool to brag? Unless you are talking with your coach!

Third, if you have a power meter, do yourself a favor and research how to appropriately use (and talk) about the numbers you are getting! If you don’t understand the numbers you shouldn’t have them on your watch. 

Now get out there, stop talking about watts and become a better, stronger rider!