Is it really all about the power?

Installing a power meter on your bike will definitely make you and your bike subject of discussion, admiration, and mockery. But do your really need one?

June 11, 2016
cycling

Old-school purists will tell you to just follow Rule #5 (Harden the f**k up), and that the all-time greats like Merckx and De Vlaeminck didn’t need ‘a computer on their stems’ to ride fast. Other people will tell you that buying ‘pro gear’ doesn’t make you a Pro cyclist. Then there will be the people who are merely interested in how many Watts you can push, and some others that just envy you because you have one.

One thing is for sure, installing a power meter on your bike will definitely make you and your bike subject of discussion, admiration, and mockery.

Power meters: 101

A power meter is exactly what it says to be: a device that can measure power. Its goal is to give a rider (and maybe his/her coaches) insight into the amount of Watts the rider is pushing at a given point in time.

Power meters come in several variations, and also at varying price points. They differ in how and where they measure power, with hub-based, axle-based, spider-based, chainset-based, crank-arm-based, and pedal-based power meters to choose from, and prices ranging from 400 to several thousand Euros.

In recent years, the introduction of more affordable power meters like the crank-based option from Stages and the pedal-based options from Garmin, Look/Polar, and PowerTap have brought power meters within reach for ‘mere mortal cyclists’. But that’s not to say those are cheap inferior products. In fact, not only is the Stages power meter one of the most affordable units on the market, it’s also one of the most accurate. And it takes about 3 minutes to install.

Random fact: Team Sky uses Stages power meters on all their bikes.

The Stages power meter is basically an original left crank with a power meter fused to it. In my case it’s an original Shimano FC-6800 (Ultegra) left-side crank. Installing it doesn’t void your warranty, and doesn’t change the way your crankset works.

I don’t need a power meter

Maybe you agree with the old-school purists or the people that will mock me for having a power meter, and honestly, until very recently I didn’t really see the benefit of owning a power meter. After all, I wasn’t a Pro cyclist, and I believed that if I just trusted my instincts and focused on proper cadence, everything would be fine.

But in reality, almost every time I rode a steep climb for more than a few minutes, I would end up completely destroying myself on that climb, unable to make it to the top without stopping at least once. I was making all kinds of excuses: my bike, my lungs (that were recovering from pneumonia), the fact that I was just too fat, or sore legs from yesterday’s ride. But my old bike has since been replaced by two much better bikes. My lungs have recovered from pneumonia, and while 92kg for a 1.91m tall rider isn’t lightweight, I’m not outrageously fat either. I simply wasn’t properly pacing myself.

Changing my mind

As I mentioned in another blog post, I recently acquired a Wahoo KICKR Snap smart indoor trainer, and started using Zwift. The goal was to create an indoor training experience that wouldn’t be so utterly boring that I wouldn’t last for 30 minutes. I succeeded. Zwift is awesome, and the KICKR Snap is a great product.

It also has a power meter, so I could actually see how many Watts I put into my virtual rides on Watopia. At first it was mostly fun and games, I tried to go beyond 1000 Watts in a sprint, tried to hold 500 Watts for as long as possible, etcetera. Then I noticed that many of the organized group rides on Zwift specified a Watt/kg range, like ‘sub 2 group ride’, or ‘2.5-3 group ride’. I started reading about what these numbers meant for a rider’s fitness, and started keeping track of my personal Watt/kg numbers. I upgraded my Strava account so I could use the ‘Power Curve’ feature to really gain insight in my own performance and fitness. But still, I didn’t really consider a power meter a necessity.

But what really changed my mind was a recent ride on Watopia (Zwift’s virtual island), where I took a wrong turn (yes, that’s possible), and ended up on a pretty long climb that I wasn’t expecting. The upside of a virtual ride being that you can just get off anywhere and be home, I decided to just go for it. Not knowing how long this climb actually was, I decided to try and ‘settle in’ at about 80% of my FTP (Functional Threshold Power) value, as in theory, I should be able to easily sustain that level of power for at least an hour.

It worked. By looking solely at power and cadence, I managed to climb a steep (virtual) hill without outpacing myself, without getting dizzy, and without feeling the need to stop. At the summit of that virtual climb, I decided to get myself a real power meter so I would have the same insight in the real world.

Riding with a power meter

Previously, my cycling computer would primarily show me my current speed, cadence, and heart rate. Even though these are pretty standard metrics on bike computers, their usefulness is debatable. For instance, speed depends heavily on the amount of wind and road quality. Heart rate is being used by many as a pacing tool, but heart rate can vary depending on things like temperature, caffeine intake, or blood pressure levels. Also, as you start to work harder, your heart rate doesn’t immediately increase. There’s a delay. Enough delay, in fact, to out-pace yourself on a steep climb.

If pacing yourself based on heart-rate data works for you, then good on you. But if it doesn’t, a power meter might just be what you need.

While my cycling computer still shows me my current speed, it has become a much less important field on my screen. The data fields I do look at during rides are power (3sec average), cadence, and ride time (so I don’t forget to eat). On a climb I might want to look at the incline (grade) as well. Speed is only important when I’m trying to beat a Strava PR, so I can compare my current speed to the average speed of my PR.