Better Cycling Through Data: Power Meters

Improving power output is one of the few ways to go faster on the bike. Power meters from Pioneer, SRM, Garmin, and Wahoo Fitness are your methods of measurement. 


Pioneer's Cyclo-Sphere software interface showing 12 points of directional force and pedaling efficiency for each leg

More power is mo betta. It's a self-evident truth of cycling: when you add more wattage to the equation, it gets better. You go faster and farther with less effort. You drop your buddies and bag personal records (PRs) on Strava. Ultimately, you have more fun. In order to produce more power, though, you need to do two things: train and measure. I'll cover the training part in a future post. For now, we'll focus on measurement.

A new category of training technology, including both hardware and software, has emerged around the measurement and optimization of power output. Quite simply, this is how much wattage your legs send to the pedals at any given moment. This value, combined with the weight of your body and bike, largely determines how fast you go. However, power output can be measured at the pedal, the crank, the bottom bracket, and the rear wheel. It can be measured as a total value or for each individual leg. So there is a lot to consider in making the right choice for your goals.

Following are three power meter systems I've been evaluating for the past six to 12 months, along with their corresponding computer head units and software:

Pioneer SGY-PM90 ($1,000): The Pioneer dual-leg power meter is exclusively designed for Shimano Dura-Ace and Ultegra cranks. It can be installed on an existing crankset for $1,000, or you can purchase the whole system for $1850. Power output is measured at the crank arm for each leg. It also measures directional force (force vectors) at 12 different points around the pedal stroke. What this essentially means is that Pioneer captures more data than any other system on the market. How to make use of these data is really the question. The ability to measure and visualize the power you're producing for each leg and how that power is being applied throughout the pedal stroke -- in real time as well as through post-ride analysis -- enables you to improve pedaling technique. This translates into greater pedaling efficiency (more speed for less energy), which the Pioneer power meter is uniquely capable of measuring. A value of 60% pedaling efficiency is exceptionally good. And while this matters to professional cyclists, amateurs have much more upside potential in this area.

Pioneer offers several different head units designed specifically for its power meters. The SGX-CA900 ($500) features a 2.2" screen, which is an ideal size for displaying all of the data points you need for interval training and optimizing efficiency. In order to benefit from Pioneer's copious data, you'll need to use both its head unit and its free, web-based Cyclo-Sphere software solution. The application can certainly benefit from a UX upgrade but otherwise lets you view and make sense of the data with minimal expertise. Alternatively, the power meter is compatible with ANT+ cycling computers from Garmin and other companies, which still capture all of the key data points for power-based training.

SRM-Cannondale Power Meter ($1,914): SRM is widely recognized as the gold standard in power meters. This is why they are so widely adopted by pro teams and why the price points are fairly high. One of the advantages of the SMR platform is how it integrates with a wide range of cranks including Shimano, Campagnolo, Specialized, FSA, and Cannondale by replacing the spider on which the chainrings are mounted. This is an ideal place to measure power, and the integration is seamless. The data you get, though limited to total power as opposed to each leg, is consistent and precise. I actually find that my SRM reads about 1o watts higher than the Pioneer (above) and Garmin (below) for a similar effort. It's difficult to know which is more accurate. Unless you're a professional, though, what really matters is a consistent benchmark of progress over time.

SRM also offers its own head units and software system. The PowerControl 8 computer is new for 2015. Encased in anodized aluminum, it has a pro-grade look and feel with customizable training screens and the new standards in power-based training KPIs. My personal preference, however, is the Garmin Edge 1000 (below) due to its mapping and navigation feature set and the Training Peaks software for data analysis, since it's quickly become the industry standard. I'll review that in more detail in a future post.

Garmin Vector 2 ($1,500): Garmin's unique approach is to build the power meter into a set of proprietary pedals. Wattage is measured at the axle of each pedal, which enables dual-leg measurement, and the data are transmitted from the pedal pods, extending off of the pedals, to any ANT+ bike computer. The downside to a system like this is that you must be OK with the performance of the pedals themselves. Shimano, Time, or Speedplay are no longer options. Otherwise, the big advantage is convenience. Unlike Pioneer and SRM, which require factory installations, you can easily install the Garmin on any bike just as you would a standard set of pedals. Which is especially useful if you rent bikes while traveling as opposed to schlepping your own bike. You can also gauge what Garmin calls "Platform Center Offset," which determines if power is distributed to the left or right of each pedal. This enables optimum cleat adjustment.

The Garmin Edge 1000 ($500) is my bike computer of choice. As with smartphones, the screens are trending bigger. And while it might feel too big at first, you quickly adapt and become hooked on the larger surface area. If you ride centuries or plan routes via Ride With GPS, the mapping and navigation features give you turn-by-turn directions and keep you on route. It supports dual-leg measurement for both the Garmin and Pioneer systems, though you don't get 100 percent of the data Pioneer generates. Garmin has its own analysis software and mobile app, Garmin Connect, which can sync with and automatically push ride data to Strava. Finally, the mobile app offers a LiveTrack feature, which enables real-time sharing of your location to individuals e.g. emergency contacts or else your followers on Facebook and Twitter.

Wahoo Fitness Kickr Snap bike trainer ($850): As fall and winter weather discourage outside riding, the indoor trainer becomes an indispensable fitness tool. The Kickr is an ideal option for those who want an introduction to power-based training. It measures power at the tire, which isn't very accurate, but it doesn't need to be. It just needs to be consistent from one ride to the next, and I found that to be the case. Plus, you don't need a bike computer. You can use any smartphone with the Wahoo Fitness app to track power output from the trainer and heart rate from Wahoo's Bluetooth heart rate strap (sold separately) and store it all to measure progress over time.