As part of a slowtwitch.com study I’ve been selected to train on PowerCranks for a year. I’ve got plenty of historical power data, so I think any potential gains from PowerCranks will stick out like a sore thumb. Nonetheless, I’m always looking for ways to crunch data. As an engineer, it’s what I do. I’m a number cruncher. So with that in mind, Monday was a scheduled recovery ride. I had planned on a 60 minute PC ride, but after 30 minutes I was getting some pain on the outside of my left hip. Still no hip flexor soreness, but the outside hip pain was troubling. I know it well as it sometimes rears its ugly head when I load up on L3 miles. Not wanting to cause injury, I headed home, switched to my race bike with regular cranks, and did another 30 minutes of riding. I was trying to ride both rides in the same manner so I could potentially get a comparison of the two crank systems.
The first plot shows how similar the rides were in terms of speed. Towards the end of the ride I felt my average power was a little higher with regular cranks, so I was slowing down to compensate. I overcompensated a little too much, however, as power averages were lower with regular cranks.
The second plot shows that in general the course rode the same with PCs and regular cranks. Note the higher power in the PC ride, particularly late in the game.
One thing I’ve noticed with PCs is that my heart rate has been higher when using them. This is clearly indicated in the third plot which shows PCs always riding high. Of interest is that from the plot it appears my heart rate is a consistent 10 beats per minute higher with PCs for areas where the power is similar. The last plot clearly (or not so clearly) shows how much more effort PCs require compared to regular cranks. I’ve plotted a ratio of power to heart rate reserve (HR-HR_resting), where I’ve assumed my resting heart rate is 36 beats per minute. The plot is certainly noisy, but does show that normal cranks are easier than PowerCranks.
The first plot shows how similar the rides were in terms of speed. Towards the end of the ride I felt my average power was a little higher with regular cranks, so I was slowing down to compensate. I overcompensated a little too much, however, as power averages were lower with regular cranks.
The second plot shows that in general the course rode the same with PCs and regular cranks. Note the higher power in the PC ride, particularly late in the game.
One thing I’ve noticed with PCs is that my heart rate has been higher when using them. This is clearly indicated in the third plot which shows PCs always riding high. Of interest is that from the plot it appears my heart rate is a consistent 10 beats per minute higher with PCs for areas where the power is similar. The last plot clearly (or not so clearly) shows how much more effort PCs require compared to regular cranks. I’ve plotted a ratio of power to heart rate reserve (HR-HR_resting), where I’ve assumed my resting heart rate is 36 beats per minute. The plot is certainly noisy, but does show that normal cranks are easier than PowerCranks.
A summary of the ride is in the table below. Average power, normalized power, heart rate, and various ratios are computed. Average and normalized power for the PowerCrank portion are higher, but only by 4 and 3 watts, respectively. However, average heart rate was a good 10 bpm higher with PCs. Computing ratios of power (average and normalized) to average heart rate or heart rate reserve show that across the board regular cranks give a bigger bang for the buck (i.e., more power for the same heart rate).
What will be interesting is if these ratios converge on each other with time or if there will always be some difference associated with the two crank systems. Clearly the principles of specificity and adapting to a different way of pedaling take time, and using slightly different muscles does alter the physiological response (i.e., heart rate response).
Time on PCs – 30 minutes
Time to date – 2.5 hours
| PowerCranks | Regular | |
| AP (Avg Power) | 154 | 150 |
| NP (Norm Power) | 166 | 163 |
| HR (Heart Rate) | 120 | 110 |
| AP/HR (Heart Rate) | 1.28 | 1.36 |
| AP/HRR (Heart Rate) | 1.83 | 2.03 |
| NP/HR (Heart Rate) | 1.38 | 1.48 |
| NP/HRR (Heart Rate) | 1.98 | 2.20 |
What will be interesting is if these ratios converge on each other with time or if there will always be some difference associated with the two crank systems. Clearly the principles of specificity and adapting to a different way of pedaling take time, and using slightly different muscles does alter the physiological response (i.e., heart rate response).
Time on PCs – 30 minutes
Time to date – 2.5 hours
1 comment:
This data could also suggest (notice my 6-sigma training coming through...)that with the higher heart rate along with similar power output, your endurance will improve quicker on PC's or at least aerobic condition occurs at a faster rate. Now whether or no this translate into power increases in the future is yet to be seen. Sounds like you are definitely working some new muscle groups - now if can you only make whole ride on Sunday on PC's....when you back from Japan, of course...
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