This article originally appeared in the Capital Bicycle Club Newsletter May 2014
About a year ago, I dipped my toes into the water and started shopping for a power meter. I wanted to use it to measure my progress with training for the coming year. What I found was a hurdle that I still couldn’t over come, no matter how interested I was in the data: PRICE! Almost everything I could find was in the same order of magnitude that I would use if I were searching for a new bike. Frankly, I’d go for the bike almost every time, so I’m just putting that out there as my bias.
Before I gave up, however, there was one product that did catch my eye. It was the PowerCal, made by CycleOps. (It’s currently made by PowerTap.) It was compact and affordable with a price tag of just $99. Since it had been on the market for a few years, there were already some good reviews I could study. As it turns out, for what I was trying to measure, it seemed like it would be a good fit. I was skeptical of buying something so inexpensive because it was so much different from other power meters.
A year later, and I’ve used it on almost every ride I’ve been on, without a complaint. The rest of this article is some of my personal experience with the device, and some of its pros and cons.
To begin with, the PowerCal operates by reading heart rate data and then calculating an estimation of wattage (power.) Done, of course, though a proprietary mathematical algorithm. This calculated wattage is then transmitted to a receiver, just as a hub-based power meter does. In my case, I have a Garmin that is the receiver, but almost any ANT+ compatible device will work. Set up is very simple, and no calibration of the device is required. You simply put on the strap and pair it with your computer.
My intended use of the tool was for analyzing power/wattage over longer distances of an hour or more, and maybe to use for fitness testing, instead of just relying on heart rate and distance. This is where one of the main limitations come into play. Short duration/bursts would be hard to capture on this device because changes in heart rate lag behind the actual output of power. Hub and crank-based devices can give instantaneous readout of this power. Fortunately for me, this was not a very high priority for me when I was considering my needs. I’ve read one review that compared several different devices at the same time (DC Rainmaker, Nov 2012.) His personal experiments showed that the PowerCal was comparable for almost all intervals greater than 30-40 seconds. Any intervals shorter than this duration were less reliable.
One complaint/observation of the PowerCal is that it has a fairly large sweep in the data that it presents, even though the average comes out comparable to other power meters. On my Garmin, I have set a field to display a 10 second average of the power output, which turns it into a fairly stable number. Honestly, though, I currently don’t use the number during training. I rely more on my real-time heart rate. I just read the power data later, sitting in front of my computer.
One of the bright shiny benefits of the PowerCal has been its portability. Since it’s based on a simple heart rate strap, there’s no hub or wheel to switch around. I’ve been able to easily get consistent and meaningful readings from trips I’ve taken on my road, mountain, and cyclocross bikes. I’ve even run with it on a few times, but my most favorite files are ones that I created during cyclocross racing last fall.
One last note I’d add is that the data you record is somewhat unique to you. It’s your heart’s response to exercise. While not necessarily a limitation, it is a fact that you will want to keep in mind if you choose to use this tool. Your PowerCal data isn’t intended to be compared to a true power meter, either. They are too different to make simple comparisons like that. Further, it would be of little use to compare your data to another person’s. Of course, it would probably make for a great conversation as you are relaxing with your riding buddies after a day in the saddle. Maybe you can even try to figure out what might be involved with that proprietary mathematical algorithm!
For the price, the PowerCal has been a very useful tool for me, and well worth the $99. As a general rider, seeking to find another way to measure my efforts and (hopefully) progress throughout the year, it’s become an invaluable tool. If you are looking for a way to enter the realm of cycling with power and can’t see clear to investing in hardware-based devices, this may be for you. Gathering useful training data is almost as simple as just putting on a heart rate strap! See you on the road.
Read more about Dr. Rosser’s adventures as an amateur cyclist www.rosserchiro.com . He is the team chiropractor for the CBC/Olympia Orthopaedic Associates Racing Team, and assists other athletes in the community. For more information, he can be contacted at firstname.lastname@example.org.