Monday, July 20, 2009

On Difficulty

I've stolen the title from one of Jorie Graham's poems for this post, in attempting to explain the Xterra Mountain Cup race in which I competed this past Saturday. I'm choosing that title because, like Graham's poem, the appearance of difficulty did not match the actual difficulty. That is to say, it was much harder than it looked or, upon reflection, with lots of numbers and equations, much harder than it was computed to be.

I'm making a reach, here, comparing excrutiatingly difficult contemporary poetry with an off-road triathlon, but when you come upon a poem by Graham called "On Difficulty," you believe that things will finally be explained. The curtain will rise, the numbers will reveal their manifold truths, the trees will part for a second. Unfortunately, Graham's poem does little to explain her poetry in general, choosing instead to flirt with your sense of clarity. Reading it is a little like knowing you have to dance a tango (difficult to begin with), but that you've got to do it in the dark, with a dwarf, accompanied by an orchestra on, at the same time, amphetamines and oxycodone. Here's a chunk of her poem "Just Before:"
At some point in the day, as such, there was a pool.  Of
stillness. One bent to brush one's hair, and, lifting
again, there it was, the
opening—one glanced away from a mirror, and there, before one's glance reached the
street, it was, dilation and breath—a name called out
in another's yard—a breeze from
where—the log collapsing inward of a sudden into its
hearth—it burning further, feathery—you hear it but you don't
look up—yet there it

OK, confused yet? And still, there is something lovely in this section of poetry, the cadences are regular (even though there isn't anything you might call a "rhythm" or "meter" to it), and there's this kind of bemused sense of wonder and exploration, the feeling you get when, as I am now, you sit at your desk in the summertime and listen to the myriad sounds of the world coming in through the window.

Right. Where am I going with this? The race on Saturday, in Beaver Creek, Colorado. My first off-road triathlon. I'm going to approach this (obviously) from several oblique angles and one quite direct angle. The direct angle: it was hard. Very, very hard—similar to, perhaps, competing in two 1-hour cyclocross races, and then popping off the bike for a nice, lung-cleansing run up a mountain. That description, though, doesn't capture the difficulty of the race. I have, in my athletic career, felt so buried exactly three times, all of them cycling events, not triathlon. The first was the Cat 1/2/3 Exeter Criterium a couple of years ago. That was my first 1/2/3 race (the top three cycling categories, for those of you who don't carry a USCF card around in your wallets), and we traveled 28 miles in 56 minutes, according to my bike's computer. That's exactly 30 mph (or just under 50 kph) for close to an hour. Any description of "how hard" that was doesn't come close to how I felt afterwards: elation, hallucination, despair, desperation. If you've read the section of Once a Runner when Quenton Cassidy runs 60 1/4 mile repeats at sub 4:00 pace, you might know how I felt. I won't bore you with the details of the other two times, but one took place at a mountain-top finish after 100 miles of racing, and the other at a 'Cross race, where I came over the finish line and then dry-heaved for about 200 meters.

The point? Sometimes these races seem elementary, simple, straightforward, but the pain and anguish your body goes through belies all of those descriptions.

OK, here's the number crunching section, since Justin tells me that Brandon would kick my butt in a geek-off (well, that's obvious, but I've got to fight back somehow).

Cycling power has become the buzz-tool for defining effort and training these days. You can calculate it using a power meter, but if you're going pretty slowly, you can figure it out longhand, too. Why slowly? at around 9-10 mph, the resistance between your tires and the surface over which those tires roll is pretty much equal to the resistance between you and the air through which you're traveling. Faster than 9-10 mph (or 4.4 m/s) and you get into some pretty hairy equations that involve calculating the frontal area of a human on a bicycle. I'm not going to go there. Still, for your own fun at home, here's the equation:

Fair = ½ Area CoefDrag Dair Vair²

Happily, the formula for rolling resistance is much simpler:

Froll = 9.8 W CoefRoll where:

W = Weight of the rider and bike, kg

CoefRoll = Coefficient of rolling resistance, dimensionless (wooden track = 0.001, smooth concrete = 0.002, asphalt road = 0.004, rough paved road = 0.008)

I'm going to assign a value of .012 to a standard, sandy, Coloradan singletrack for the coefficient of rolling resistance, and I + my rented bike = 93.63 kg. So Froll = 11.01. I'm calculating a force, here, so I'm assuming I'm figuring this all for Newtons? Not sure. Anyway.

Another important consideration, of course, is the force of gravity. This one is also pretty easy to figure out. First you have to figure the average gradient of your climb, which is simple. I'm going to use the opening climb of the race, which was brutal. Coming out of the lake, you pedaled along a nice paved road for about a mile before kicking directly upwards. You then climb 2000 ft (610 m) in 5 miles (8 km). That's an average gradient of 7.6%, and you've got to do it on dirt and sand and grass. The force of gravity is computed as such:
Fgrad = 9.8 W grad. Here we go. W is the weight of the rider and bicycle, in kg. So we get 9.8*93.63*.076 = 69.74. I know I should be labeling my units, but I just don't know what they should be. It will all come out in the end.

Power can be figured out as such: P = (Fair + Froll + Fgrad) V. Happily, as I said earlier, I was only traveling around 10 mph (took me 1:35:00 to complete the 15.5 mile course), so Fair= Froll. Thus, we get the following figure: P = (11.01 + 11.01 + 69.74) 4.4 m/s. It comes out to 403 W.

403 watts is a big number, and you can take the time it took me to make that first climb (around 45 minutes) to figure out the work I did. Power = work/time, so if you just slot in 403 W = x/2700 s (we're working in seconds, here, remember) you get 1,088,000 j, or 1088 kj for simplicity's sake. It works out to about .302 kwh.

What do all these numbers work out to? Well, like I said above, they are big numbers. 1088 kj is a lot of work. 403 W for 45 minutes is a large outlay of power, probably one of my better figures.

I got passed by close to 20 people on the bike leg of this course. Now, I'm bigger than most (80 kg is huge, for cyclists), and I was hauling around a relatively heavy mountain bike (I did get some props/stares for showing up to a professional race on a rental), but a lot of these guys went past me with ease. They certainly went past me with ease on the downhills, too, where my weight, ostensibly, should pose an advantage. Sadly, this isn't on-road racing, where things are straightforward and the only limiters are a) your fitness and b) your mental ability to do things that your brain really really doesn't want to do. I learned, the first day I raced Cyclocross, that the strongest guy doesn't win. On Saturday I was neither the strongest or most skilled guy, and I finished somewhere in the top 30, well out of the professional field.

All of these numbers, however, and assurances from me still don't tell you the whole story. Riding your bicyle uphill can be quite hard. Coming back down and then running back up the mountain (400 m in 9 km) is even harder. I spent most of Saturday sitting in the passenger seat of the car, eating, saying things like: "It was quite difficult," in a meager, confused tone of voice.

1 comment:

April Bowling said...

That was the best (multiple) description of a race ever...