Playing With Power

The combination of buying a Wahoo KICKR trainer along with a winter that was bad enough to ensure that every ride this winter was an indoor ride resulted in me getting pretty familiar with power.


I also took some steps to better educate myself such as reading Joe Friel’s “Power Meter Handbook” so that I could better understand concepts like Functional Threshold Power (FTP) Intensity Factor, (IF) and Training Stress Score (TSS). The book is good but very technical and for someone with my background, a bit difficult to absorb.


Nevertheless, I was able to complete a test for my FTP back in March. It turned out to be a fairly paltry 202 watts. This is basically saying that’s the power I can hold for an hour ride. From that, my coach was able to set up a series of Power Zones for me from 1 (easy, active recovery) to 5 (VO2 Max).


That was great for several workouts but the thing that happened in the last few weeks is that the weather got good enough to start actually riding outdoors—you know, like you’re supposed to.


Until a couple of weeks ago, that meant no power data. All I had was HR and Cadence through my Garmin sensors.


That changed when (after a five week wait) Stages Cycling in Boulder shipped me my new crankset, complete with their crank-arm-based power meter. I won’t rehash all of that technology here but if you are interested, you can check out the technical section of their website, or better still, this DC Rainmaker product review.


The most important thing to understand about this meter is that it measures power only from the left side—specifically from the strain being put on the left crank arm. Doing so allows them to offer products starting from an incredibly low $699.99 which is quite competitive in the market. The nearest competitors (using hub or spider-based systems) are around $100 more. I had to spend a little more to get an entirely new crankset but my guess is that a lot of folks will be able to swap out just the existing arm. They also appear to be adding additional brands and models on a regular, albeit slow, basis.



Like anything new, there is always a concern about whether or not it will work. I was quite pleased to discover early on that I started getting readings right away. The workout I had for the day of my first ride involved a series of intervals into my top Power/HR Zone for declining periods of time.

A couple of big spikes are probably related to starting up a hill in higher gear and not really indicative of any actual work. Nevertheless, it provided me with a good read on just how hard I was working.


In fact, it also helped negate the effects of bad HR data. Like a lot of people (especially those in drier climates like Colorado) HR meters are notoriously susceptible to spikes due to static electricity. That can be created just by riding or (as was the case on the day of my workout) by high wind. As a result, I know I can’t trust the data I’m seeing about my heart rate. Power, however, does not care. You are either working or not and the results are immediate.



This is not to say that I don’t see some value in HR data. Indeed, I’m waiting for a couple of optically based systems to come on the market and buy one. However, when it comes to the ride, there’s really no better way to evaluate how hard you are working.


One controversy around Stages is the question of whether or not you’re getting reliable data by measuring just from the left side and then multiplying that number by 2. The DC Rainmaker article addresses this better than I could. That said, I believe I’m getting the data I need. Is it possible it’s off? Sure. Does it matter that much to someone of my ability level? No, not really.


Of course, in a sport where it seems like there is always some new expense, $700 is still nothing to sneeze at. Despite several new entrants, power meters have not come down in price to something more reasonable like say $300 - $400. Perhaps that will change. They used to go for no less than $1500 (and often times more).


This was a decision I put off multiple times, but now that I actually have the new cranks installed and working as they are supposed to, I’m really happy with the results. The new feature serves the dual purpose of providing me with better performance data as well as being able to do the workouts assigned to me by my coach.



As always, thanks for reading.