Power and the passion

An introductory guide to power meters

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Power meters are no longer the preserve of the highly conditioned elite athlete. From their origins as a halo product in the 1990s and early 2000s, power meters have increased in popularity to the point where they’re close to being standard-issue equipment on higher-end road bikes.

For those who’ve had a taste of training with power, they are quickly indispensable, and seen as a vital tool to maintaining or improving condition. But for those who haven’t used a power meter before or are less performance-oriented, they can be seen as expensive and irrelevant — an extra bit of equipment serving up a confusing mess of numbers with little tangible benefit to offer.

But is this a fair assessment, or can there be benefits to using a power meter for a wider range of riders than racers and Strava junkies? Can a novice to power training access the benefits of the technology, and what potential can they untap? And of the broad and constantly growing range of power meters on the market, what type is most appropriate for your needs?

How power meters work

Let’s go back to the very beginning and cover the basics of what power meters are, and how they work.

Quite simply, most power meters use strain gauges to measure the torque created when you pedal, multiply that by your cadence, and produce a number that is your power output in watts. The resulting data is transmitted by Bluetooth or ANT+ to a compatible computer display (such as a Garmin, Wahoo or similar GPS unit) which allows you to track your performance on the go and record it for later analysis.

Power meters are most commonly located at the pedals or crankset, with common variants including:

Pedals: PowerTap P1, Look Power Pedals, Garmin Vector
Crank/spider based: SRM, Quarq, Power2Max, Stages, 4iiii
Chainring: PowerTap C1

Locating power meters at the pedals or crankset is beneficial because they’re immediately adjacent to the source of the power, and in many cases are able to provide additional information around pedalling efficiency and symmetry.

Away from the pedals/crankset, some of the more common options include:

Hubs: PowerTap’s well-regarded and accessibly-priced hub-based power meter has been around since 1999, going through a number of improvements over the years to take it to its current third generation. PowerTap is the only hub-based power meter manufacturer, and is widely considered a benchmark for accuracy across the entire industry.

There are some more obscure options on the market, too, with wildly divergent degrees of accuracy:

Wind-based: PowerPod
Shoe-based: Luck Potentiometer

Then there are some even quirkier options such as the AroFly power meter, which is installed as a valve-cap. Some of these variants work surprisingly well; some of them are fundamentally flawed.

What type to get

So you’ve decided to take the plunge and pick up a power meter. Which variety is the best choice? Your choice will ultimately be defined by your particular needs – your budget, the degree of accuracy that you desire, and any specific requirements of the bike(s) you’ll want to mount it on.

Crankset-based systems like SRM were considered the gold standard for many years, but they aren’t easily interchangeable between bikes and are fairly expensive as well.

Single-sided crank systems, like Stages’ initial offering, represented a new frontier in the power meter era, significantly reducing the cost-related barriers to entry and helping usher in a new era of affordable power.

PowerTap’s rear hub-based power meter is an easier option to transfer between bikes, so long as your bikes have the same axle spacing and braking system. Assuming the wheel is compatible, hub-based power meters are an excellent option offering significant perks, all without the involvement of the drivetrain.

Pedal-based power meters – with their ease of transfer between bikes and dual-sided power readings – are arguably the most straightforward of the lot. The PowerTap P1 power pedals are a particularly user-friendly example — they don’t require torque wrenches or painstaking calibration when transferring from one bike to another, making them one of the least intimidating options on the market to use or set up.

The one major downside of pedal-based power systems is that they may require you to change your cleat standard – if you’re wedded to Speedplay pedals for biomechanical reasons, for instance, they may not work for you.

Barriers to entry

Arguably the greatest barrier to entry into the power meter game is expense, although this is increasingly a diminishing concern. There are concessions towards affordability in single-sided power pedals and cranks, at the minor expense of purity of data and left/right analysis.

This has significantly broadened the market, allowing the introduction of simple entry-level power meters like the heart-rate based PowerCal, which is less accurate than on-the-bike meters but is an excellent low-cost tool for someone dipping their toe into the power-training space.

On some higher-spec bikes from major manufacturers such as Specialized and Giant, power meters are even included in the price – a fact that both underlines the growth in popularity of power meters and potentially signals their broader roll-out in the market. It’s not just the bike companies that are coming to the party, however. As of this year, Shimano has a power crankset available and SRAM has a dedicated power meter manufacturing sister company in Quarq.

Why train with power

Training with power eliminates subjectivity, providing an honest and objective measure of your effort – and giving you a clear yardstick to measure your progress against from day to day. Unlike average speed, which is often used by amateur cyclists to assess their performance, power data is unaffected by wind or hills and allows a user to compare the relative efforts of their rides across different terrain, on different days. And unlike heart rate measurement, power data is instant in response and not affected by factors like hydration or how well-rested you are.

This information is immediately accessible and can be used to measure efforts and tailor training to particular targeted zones, allowing the user to maximise their performance or work in conjunction with a training program or coach to hit specific fitness milestones.

There’s so much data collected by a power meter that it can admittedly be a little intimidating to wade through at first, but even for the casual user most of it is genuinely useful in the insights it provides. Case in point: PowerTap’s Advanced Pedal Metrics, which allows a user to dive into the mechanics of their pedalling motion. From this data, you’re able to see the efficiency of the pedal stroke and the pedal angle. These can be handy diagnostic tools to isolate issues with a bike fit or positioning, and provide useful and instructive guidance on areas of improvement.

There’s plenty of valuable insight that can be gleaned by assessing your power curve, as well. By analysing your peak power over a range of durations, you’ll be able to see exactly what areas you need to improve. Perhaps you’re lacking kick over five seconds, or a minute, but stack up well over an hour? With a power meter, you can quickly identify strengths and weaknesses and work to overcome them.

Learn the lingo

FTP:
Functional threshold power. The maximum power you’re able to hold for an hour, often calculated by multiplying your best 20-minute effort by 95%. You can extrapolate from this figure to determine your power zones.

Power-to-weight:
Especially when climbing, there are two ways you can get faster: by increasing your power, or by reducing your weight. Power-to-weight is your power figure divided by kilograms.

Normalised power:
Normalised power accounts for differences in power figures over varying terrain. On a flat road, it’s far easier to maintain a steady effort, and the average power will closely correspond with the normalised power. On a hilly course, which requires higher power output on the climbs and periods of lower power output or freewheeling on descents, the average power won’t be a good representation of the actual effort. Normalised power accounts for this discrepancy.

On the road – a testimonial

We set up power-agnostic CyclingTips employee Iain Treloar with a set of PowerTap Pedals for a couple of months, and let him find out if they were a revelation or redundant. Here’s what Iain had to say:

Full disclosure: I’m a keen but completely non-competitive road rider, and I’ve never been tempted by power meters. My riding was, I told myself, for the purity of it. I’d mutter little commentaries to myself about how my schtick was riding on ‘feel’, and then predictably implode halfway up climbs when I was going for a time. So when a pair of PowerTap’s P1 pedals landed on my desk for assessment, I was more than happy to give them a go.

Finally, I reasoned, I might be able to put a number on just how ordinary a rider I was.

I blocked out some time for set up, but I needn’t have bothered. Fitting PowerTap’s pedals is as simple as changing pedals – no pods to fit, no fancy tools required … they just plug and play. A minor tweak of my Garmin settings and I was on my way, squinting down at my computer display for unfamiliar numbers.

It took a week or two to start wrapping my head around it all, and with that process came the slow dawn of understanding about why people were so fond of these things. Chasing a power number became something of a carrot, encouraging me to push that little bit harder to maintain effort through the full duration of climbs.

Where things got really interesting, though, was in delving into those numbers in greater depth. The first concerted efforts to work out the parameters of my power figures were eye-opening: my five-second sprint was virtually non-existent, whilst my efforts over 20 minutes or an hour were less obviously embarrassing. There was plenty of room to improve across the spectrum, but at least I now had something to aim for and a way of tracking my progress.

I wasn’t sure quite how power training would fit into my life, but it’s surprised me. Rather than measuring myself against vague markers of form, things are now far more black and white. Use of a power meter has cut through the excuses. If I want to improve, I now know what I need to do, in which areas, and whether I’m on target to get there or not.

Powering up

To put it simply, there’s never been a better time to buy a power meter. There’s greater depth in the market than ever before and you’re sure to find something out there that suits your bike(s), your riding, and your budget.

This last point is particularly important — the expansion of the power meter market means prices are lower than they’ve ever been. No longer do you need to spend thousands to get power data. Nowadays a few hundred dollars will get you everything you need to start learning more about your riding, where your strengths and weaknesses lie, and how you can improve on the bike. And who doesn’t want that?

About PowerTap

Wisconsin-based PowerTap offers a broad variety of power meter products across a range of budgets — chainring-based models, pedals and rear hubs. PowerTap’s entirely US-manufactured power meters provide the assurance of independently-verified accuracy with quality tools and after-sales support for its users.

For more information, visit the Powertap website.