Saturday, July 26, 2008
2 weeks in Japan
I'm a week out from the TT event, so my use of PCs will be somewhat limited. I'll be on them several times this week, but the real exclusive use comes in one more week.
Tuesday, July 8, 2008
Crank comparison – PowerCranks versus regular cranks
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.


| 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
Sunday, July 6, 2008
Getting Dropped
Nonetheless, Sunday brings the "easy" group ride. I headed out with the intent of doing the full 38 or so miles on PCs. Of course, with pal Dan on his Specialized Transition TT bike, and his claim that "I'll just put it at an easy 250 or so on the front" I knew that it was going to be a fast "easy" ride. That 250 W or so would be 25-26 mph, and doing that after just a couple of days with PCs would be tough. I was dropped (would never happen with regular cranks), so I just tried to ride a consistent pace. My pedaling with PCs has certainly improved, but my legs were ablaze with pain. The PCs were kicking my butt this morning. I decided to make it a bit of an interval session - turn the cranks 100 revolutions, feel my legs burn, get the heart rate up, stop pedaling, recover by dropping HR by 30+ bpm, and repeat. I did this for an hour, so I doubled my longest ride with PCs. That's 2 30 minute rides and now an hour long ride with the things, and yes, they hurt.
Average HR for the hour was 120 bpm, and that was with a fair amount of coasting. By comparison, Saturday's "hammerfest" portion of the group ride (about 2.5 hours) was 131 bpm average and 233 W normalized. It didn't feel nearly as hard as the PC ride. I came home after an hour, switched bikes, and headed back out to intercept the group. Perceived effort on the non-PC bike was SO MUCH easier. The hardest part of that portion (not very hard), was 117 bpm average and 194 watts normalized, a true recovery pace for me. But honestly, the PCs just kicked my tail today.
Time on PCs - 60 minutes
Total time on PCs - 120 minutes
Friday, July 4, 2008
PCs, day 2
I did a completely unscientific test where I cycled one loop of a neighboorhood block on both my training bike with PCs and race bike with normal cranks. Times were identical. Perceived effort was higher with the PCs, and my heart rate for the loop was a consistent 15-20 bpm higher with PCs. That 15-20 bpm equates to around 40-50 watts for me. That's too much to be accounted for by rolling resistance (virtually identical tires) and aero (was on the tops on both bikes).
Next week or as soon as I get back from Japan, I'll do some back-to-back testing on the two bikes again, but this time with power.
Time on PCs - 30 minutes
Year to day - ~65 minutes
Thursday, July 3, 2008
The PowerCrank experiment begins
I was cautious at first since I've heard plenty of stories regarding sore hip flexors with PCs. My 35+ minutes of riding was a breeze. No pain whatsoever. I felt I could have easily gone over an hour the first time out (and may do that July 4th in the morning as a warmup ride for Friday night track racing). Now the pedaling style was certainly odd. I definitely need practice pedaling with the PCs. My left and right legs were not in synch. Part of that was due to the pedal issue; once switching to the Time pedals, my pedal stroke was much more efficient. One thing I noticed was that I had no difficulty bringing the pedals over the top on the upstroke. I'm wondering if 10,000+ miles a year on completely flat roads has simply refined my stroke to that "perfect circle". I haven't been on my Computrainer in over a year for a Spin Scan test, so maybe it's time. I also found that to make a more even stroke, I tended to increase my cadence and push harder on the pedals. Maintaining a consistent pace was tough; my legs felt like they wanted to push into zone 3 to 4 just to stay balanced. I'll have to monitor that more closely.
The only bummer is that I can only use the PCs for another few rides before I hang them up for 2 weeks. I have to head to Japan for work, and I'm not lugging the beast with me. That honor goes to my road race bike, which at under 16 lbs, is a nice match for the local mountains there. I'd fall flat on my face trying to use PCs up 8-10% grades, and they won't match my Specialized BB anyway. Sorry Frank - it's hard enough remembering to ride on the left side of the road without worrying about my pedal stroke in the mountains. But once I get back I'll be on them probably every day.
To date time with PCs - ~35 minutes
Friday, June 20, 2008
PowerCrank Preliminaries
To look for positive trends from PCs, I will throw out a couple of the low points in the data. There were some definite periods where the month was comprised of only a couple of rides (due to illness or travel). The periods thrown out are June and July 2004 (was going to Japan or Europe almost every other week) and September and October 2005 (was in Japan almost all of Sept without a bike, and October was like getting on the bike all over again).
To look for positive trends, I’ve taken the above data and averaged it across a yearly basis by month. So the May month is an average of the Mays from 2004 to 2008. The plots below show the average (thick black line) and 1-sigma, 2-sigma, and 3-sigma lines for the reported data. If PCs work, I expect my numbers to be above the 2-sigma line (thick yellow line). That would mark a small improvement in FTP, but after years of training where I feel I’ve reached a limit on FTP, even a 10 W gain would be significant (translating to 30-60 seconds quicker in a 40k).
