One area that I do see an extreme difference is when comparing to other riders on equivalent segments in Strava. Below is one example of a speed run segment in my area shown below. My top result is highlighted below in between others for that segment. As you can see for roughly equivalent speeds, I putting out 201 watts compared to everyone else running around 270 to 290 watts. Hmmm? 70 to 90 watts off? Now most of these powers were calculated using Strava’s algorithms, but the entry just above me used an actual power meter of some sort. That power meter seems more inline with what Strava is calculating for others compared to the PowerCal. So again, while the PowerCal is consistent, I don’t believe the accuracy of wattage is very good.
Problems on the Run
I also use my PowerCal for monitoring my heart rate while running. This is one area that I have had the most issue with this product. It appears to “flip out” frequently at different times during my runs. What I mean is that the heart rate just goes crazy and maintains a spiked reasding well outside my max heart rate. The first couple times this happened I kind of panicked at first, thinking I was having a heart attack or something. Eventually I realized it was just the unit. I always use a gel for the contact patches to help eliminate these spikes, but it doesn’t really help. I have also tried new battery, tightening the strap and taking the unit off for a few minutes. The latter seems to have the best affect on resolving the issue. You can see from the heart rate graphs below from my runs what this looks like. The strange thing is that it doesn’t occur on bike rides. It could possibly be from the up and down motion of running.
I have been eagerly wanting to start training with power, but am too cheap to fork out the big bucks for a PowerTap or a crank-based power meter. Then came the CycleOps PowerCal Power Meter/Heart Rate Monitor. For ~$100 I could have a fairly consistent way to measure way to quantify my rides. I read the review over at DC Rainmakers’ site and was tossing it around for awhile. Then my Garmin “Premium” (HA!) Heart Rate strap totally died on me so I needed a new HR monitor anyway, so I thought for $30 more I would give it a whirl.
At first I had nothing to compare it too, then I ended up bucking up for the Kinetic inRide power meter for my Kurt Kinetic Road Machine Trainer. Kurt claims that the inRide is around +/- 1-2% accurate(not sure where I saw this), so I thought this would be a good unit to compare too.
I used my inRide on my laptop with the TrainerRoad workouts and then paired up the PowerCal with my Garmin 910xt. This one way to make those winter workouts a little more fun I guess.
As you can see from the table below, that PowerCal has been running about 20-30 watts below my inRide. It seems that it is much lower especially at the higher wattage levels. Despite this I feel it is fairly consistent, especially on a total ride basis. The individual readings on the PowerCal are all over the place, which is also cited in DC Rainmakers’ review as well. But if you assess the total ride wattage it is pretty close.
The PowerCal does not have any input as to the specific riders’ age, height, weight, or sex and calculates strictly on heart rate. It does not peform any type of calibration either. It astounds me as to how they can accurately calculate this very specific measurement with so many unknown variables. Given this it does a really decent job at it. Pretty amazing really.
I will continue to assess this tool, but it seems like a fairly good tool for measuring an overall ride for the money. I would not count on it for assessing your power output at a moment in time during a ride. The one week I noticed my HR was a bit more depressed training than normal and I did see some of that indicated in the power measurements as well.