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Bike power meters for triathletes: what to know

Our in-depth guide to bike power meters and their uses for triathletes

The advent of power meters in sport may seem like a recent phenomenon, but the story actually begins in Germany in 1986 when Ulrich Schoberer of SRM designed, manufactured and submitted his patent application for the first ever spider-based cycling power meter. 

Ulrich’s brother Rudolf explains. “Up until the 80s, no adequate method had been found to measure performance on a bike in training or racing; athletes had to rely on lab testing instead, an intermittent check-up at best that didn’t tell athletes anything about how they were performing day-to-day. And the most important performance – during competition – couldn’t be tested.”

Those first power meters cost $10,000 and it’s taken a lot of time for prices to start dropping. The component parts aren’t expensive, what ramps up the cost is the R&D work that’s necessary to make the units reliable. A power meter has to produce consistent data no matter what. Installation, temperature variations and a host of other factors make this notoriously tricky. 

With patents expiring and a better understanding of the technology, more manufacturers are developing cycling power meters, and we’re now seeing some significant price drops from brands such as SRM, Rotor, Cycleops, Stages and Quarq. But what gains can be made using a power meter for triathlon? Let’s find out…

POWER METER PROS AND PITFALLS

On the bike, a power meter gives you an absolute gauge of the mechanical work your body is doing. Unlike heart rate, it’s unaffected by either internal or external variables. Race-day nerves, weather conditions, cardiac drift, fatigue… the watts you put out are the watts you put out. For pacing a long-course bike leg, training guru Joe Friel sums it up best:

“It’s been said using a power meter in an Ironman is almost like cheating. While others are trying to gauge intensity through a cloudy veil of emotion, which makes perceived exertion and even heart rate nearly useless, the athlete with a power meter is focused on a number that, if maintained with only slight variations, will produce an optimal bike split.”

The more data you accumulate, the mightier it becomes. You can score the impact that every workout has on your body and significantly reduce the risk of overtraining, making hitting race-day form a predictable science, rather than a dark art.

A power meter isn’t an instant magic bullet for cycling greatness, though. You still have to put in the training hours, and learn how to interpret and apply the data. Power meters don’t tell you how hard your body is working, only the power you’re generating. Heart rate is far from redundant; we’re not machines and this has to be taken notice of. There’s an argument also that an over reliance on power meters takes the spontaneity out of racing, an accusation levelled at Team Sky.

Paralysis by analysis

Controversial but undeniably successful tri coach Brett Sutton is against the use of power meters for his pros and age-groupers alike. “Regarding tech, it’s a crutch. And the first thing I do with my athletes is kick the crutches out.” Brett has a point, you certainly don’t have to own a power meter to become a successful rider, and it’s possible to become overly reliant on one. Plus, technology can fail, and sometimes you’ll just have a bad day, meaning you won’t physically be able to exert the power you want to, regardless of what the screen is telling you.

Are triathlon gadgets a good thing?

From a technological perspective, enhanced analytical software and improved sampling rates will allow pedal strokes to be scrutinised with ever increasing detail. You can already evaluate your torque effectiveness and pedalling smoothness for each leg with the latest metrics available from Garmin. Can you have too much information, though? Certainly paralysis by analysis is a criticism already levied at power meters. 

There are mutterings of integrating power meters with electronic shifting. Simply plug in your desired output and cadence, start turning your legs and the rest will be done for you. Would this be technology assisting cycling or turning us simply into mindless engines? It’s guaranteed that the price of power meters will continue to fall as more manufacturers and different systems enter the market; power data will become the norm.

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THE BIKE POWER METER COMPONENTS

Strain Gauges

Whether in the hub, cranks, bottom bracket or pedal spindles, these are the little gizmos that are at the heart of any reliable power-measuring system. Invented in the late 1930s, they’re composed of a silicon or foil pattern mounted on an insulating backing. An electrical charge runs though them and, when they’re flexed or strained, this deforms them, altering their electrical resistance, which can then be measured and expressed as watts. 

Battery

To create the current through the strain gauges and to transmit data, a power meter needs power. Relative to the spaces that power meters occupy, batteries can be bulky and, especially with weight a major consideration for many riders, neat battery-siting solutions are a perennial headache for developers. Decent battery life and user serviceability are also imperative.

Housing

All of these sensitive electronics are then placed in some of the wettest and muckiest areas on the bike. The housing has to be fully waterproof and resistant to the unavoidable knocks and vibrations of life on the road. Again this robustness will add bulk, which is another tricky design hurdle to overcome. 

Connectivity

Wireless connectivity is now standard for power meters, allowing them to talk to the rider’s head unit or mobile phone, their computer for uploading ride data, turbo trainer for indoor workouts and to receive software updates. ANT+ has been universally adopted by almost all manufacturers, with many also now bolting on additional Bluetooth connectivity. 

Head unit

Where the data is displayed to the rider. With the advent and uptake of ANT+, now you can have all of your power metrics, heart rate, ride stats and GPS all displayed on one device. 

Analysis Software

Recording, understanding and interpreting vast amounts of data is really what makes these devices so powerful. Software developers such as TrainingPeaks are constantly pushing the boundaries of what this data tells us and how it can enhance your training and performance. 

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