PowerTap PowerCal Review

As of June 10, CycleOps let their Grassroots Athletes, including me, know that the PowerTap brand was being spun off from CycleOps.  My PowerCal is still branded with the CycleOps logo, but I think it’s largely the same product.  After using it for almost 3 months now, I feel it’s time to give some thoughts.

A note first: I am, as mentioned, a CycleOps Grassroots athlete.  That means I get product for a considerable discount.  I still had to pay my own money, but was looking into the PowerCal before I was brought on-board.

For those unfamiliar, the PowerCal is a heart-rate based power meter.  Using algorithms built into the transmitter, it sends both heart rate and estimated power data to any ANT+ compatible head unit.  In my case, this is a Garmin Edge 500.  CycleOps and PowerTap have been pretty clear that they know this kind of number crunching will never be as accurate as actually measuring deflection or stress with a “proper” power meter.  However, for those of us who either cannot or will not spend $1000 on a PowerTab hub, this will have to do.  The question is, how much of a compromise is it?

Last year, the Velovations Enterprise at Michigan Tech was doing some research for CycleOps and I served as one of their human guinea pigs.  I rode a fixed loop a few times with a real PowerTap wheel and a Joule head unit.  They let me download my data for posterity, which was nice.  During those three rides, my average power was between 220-250 watts.  This was a 1-hour loop where they asked me never to stand while pedaling and to just try to ride moderately hard.  This all happened right near the end of the cyclocross season, so I was pretty close to peak fitness for the year.  So I have a baseline of real power data to work with.

I haven’t ridden that same loop with the PowerCal, but the readings from my other loops tend to give average power values in the 200-210 range and a threshold wattage of 232 (according to Training Peaks).  I would generally say that, without any kind of setup or tweaking, it’s reading about 10-20% low for me.

My basic reaction to this is: So what?

I am a reasonably competent age-group cyclist.  I’m a Cat.3 cyclocrosser and Cat.2 mountain biker that rides hard, but has a lot of other things on my radar each week.  If I get 7-8 hours of riding in during a week, I’m pretty happy.  If the numbers I get out of the PowerCal are a little low, what does that matter?  I’m only comparing me to me.  If I look back at my Strava or Training Peaks data and see my threshold power value climbing, it means I’m getting more fit.  Strava and Training Peaks can still look at that power data and give me Fitness & Freshness data (or the TSB value, for those in the Training Peaks know).  Ultimately, power meters are really about making it possible for me to focus my training, not to play one-upsmanship with other cyclists.  It’s about what I’m doing compared to where I’ve been, not where I am compare to somebody else.

If I’m training with numbers from the PowerCal, how well does that work?  That’s a little harder to answer.  The raw power numbers displayed on the screen are pretty crazy.  They change very rapidly all over the place, even during a fairly constant effort.  I started out with my Garmin displaying the raw power numbers, which was almost completely useless.  I switched it to a 5 second average, which was better.  Now it’s set at a 10-second average, which is usable in training.  If you have a target wattage for a given interval, you can usually use that average power as a goal.

It’s also worth noting that I have had far fewer issues with the heart rate numbers going bonkers.  Frequently, at the beginning of a ride, the Garmin heart rate strap would report constantly rising heart rate values, up to 230 bpm.  I’m pretty sure my heart isn’t beating like that.  The PowerCal has only done that once.

So you’re coming to the end of the review.  You’re still wondering, “Should I buy this thing?”  If you’re looking for a review on the PowerCal instead of one of the more expensive PowerTaps, the answer is an unqualified “Yes”. This gets you in the door to training with power.  It will change your mindset on the intervals you do and how you quantify fitness.  And just as a heart rate monitor, it’s the best I’ve used (compared with Polar and Garmin straps).


2 thoughts on “PowerTap PowerCal Review”

  1. I’m not sure if you still use it… but calibrating the PowerCal to your specific HR/power relationship makes a big difference. You can also tweak the calibration factors manually, which allows you to limit the ridiculously big spikes as your HR ramps up responds to hills. Of course this requires the use of either a borrowed PT wheel or virtual power on a trainer.

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