Monday, March 17, 2014

Level up

I have been frustrated with my new power meter (Powertap G3) since I started using it in place of TrainerRoad's otherwise excellent Virtual Power calculator. It's largely psychological, in that my FTP is lower than VP estimated it to be, but I had been advised to expect this. However, it's still hard to stare at a power target and struggle to hit it knowing the last time you saw that number it was at a much lesser effort. The other component to my frustration is of course physical; the difference between riding at 75% and 80% FTP is no small step, and the difference between 75% and 100% FTP is a VERY large step.

I've come to understand why - with virtual power, the calculation is based on wheel speed and resistance, where speed is variable and the resistance curve is constant. While my particular trainer (CycleOps Fluid2) has a well documented sloppy curve -it's not consistent, depending on temperature - the bigger problem in my observation is from smoothness of pedal stroke. To understand this, imagine the pedal stroke split into quadrants around the crank. A single pedal stroke, for simplicity, can be though of as occupying half the circle, since the other leg begins its power stage as the one leg ends its own. Now imagine what happens with a masher, or one that creates the bulk of their power in one quadrant, as opposed to a smooth pedal stroke throughout two quadrants. If they apply, say 300W in quadrant 1, and 100 in quadrant 2, multiplied by 2 (two legs), that's an average of 200W. Let's say that makes the wheel spin at an average of 22mph. Now over to the power meter; applying 200W of consistent power only spins the wheel at 20mph. Quelle horreur! So why not just use the masher stroke?! A worthy question. Because take the bike off the trainer, and you aren't dealing with the smooth resistance of the trainer, you're dealing with wind, topography, and racing stresses. You're also making sure you don't overcook yourself on the bike (if you're a triathlete that is) so much so that you can't compete on the run. Nope, constant power is the coach in your corner...can't get away with surge pedaling. You need something measurable and repeatable.

Anyway, so back to the lab...borrowing a video game term from my kids, I 'leveled up' this weekend, and in one fell swoop seem to have increased my tolerance for lactic acid. It still kicks in at the same point, but if I stop thinking about how much things hurt and start thinking about how damn strong I am (visualization folks, not ego problems), there's a lot more in the tank that I previously had found. I'll be doing some more work with longer (ie 10-15 minute) intervals at 95-105% FTP using my last test, as it's feeling like I'm higher than that now. My goal wattage is no longer a freight train travelling towards me in the tunnel, it's the *actual* light at then end of the tunnel. I was getting mentally beat up by my power meter until this happened, it's about time.

I'd be remiss if I didn't log another part of the puzzle - I moved my cleats back. This rather small, seemingly innocuous change (we're talking about 3mm difference) relieved a strain I felt in my upper groin near my glutes after about 45 minutes of riding, and translated into fatigue quickly. I experimented with it on a longer (2hr) ride yesterday and felt like I was able to hold my targets better, or at least with greater comfort. I had tried sliding the saddleback and height up to provide the same tweak, but it put me in a strange place on the bars that wasn't good, and tightened me up on my back pedal, so I moved the saddle back and adjusted the cleat instead, finding that significantly more comfortable. I can now get steeper as well, although it's not something I think I'll set up permanently; I'm very much enjoying the relief in my back since adding the extra 5mm spacer under the headset. There's now 3 under there, but it feels great.