Tuesday, June 19, 2012

Measuring the Don Tyson

Donald is only simulating here for the photo. I took the actual measurements with 60 psi in the tires and my fat butt on the seat.

My tape was long enough to measure a full two turns of the front tire which came to 146 inches, which astonished me considering that my bike has what are called 24-inch wheels. Turns out the wheels themselves are nowhere near 24 inches in diameter. Who knew!

This is my starting line for the next few months, the expansion joint closest to the traffic light pole at the southeast corner of Don Tyson and Johnson Road.

This is my turn-around line, immediately before the entrance to the used car lot for Kent Dobbs Hyundai.

To make the counting more manageable, I measured from the starting line to the crosswalk at Cambridge several times and then measured from the crosswalk to the turn-around line at Kent Dobbs. From the starting line to the crosswalk, my counts were 200, 201, 191, and 201.6. I disregarded the third result as a counting error and settled on 201. My counts were 387 and 388 from the crosswalk to Kent Dobbs so I settled on 387, not wanting to overestimate the distance.

Crunching it out, I decided to call the whole out-and-back as 1.355 miles. My math professor sister is no doubt cringing that I would be so confident of my measuring system as to express the distance with four-significant-digit precision, but I don't care. That's what I'm going with. Conveniently, I measured from the crosswalk down Cambridge to the bottom of the steps to my apartment and found it was within a few feet of 201 turns, meaning that bathroom breaks will not require any special calculation or recordkeeping. How handy!

Also handy is the distance itself. However accurate my measurements are, I'm confident that 10 laps is longer than a half marathon and 20 laps is longer than a marathon. I'm also confident that 11.5 laps is closer to 25km and 23 laps closer to 50km than trail races of those nominal distances typically are. The accuracy of my measurement is adequate for my training purposes.


Martijn said...

'Meten is weten' we Duch say. It means 'measuring is knowing' but with a cool rhyming effect. Another fine post!

red dirt girl said...

So you really AREN'T kidding, are you ??? So how are you going to simulate trail conditions - you know, snakes in the middle of the path, low hanging branches, thorns, a rock or two to twist your ankle on .... or is this just a lesson in building endurance ??


Hi Dave!

Dave Renfro said...

Martijn, I will be repeating 'meten is weten' all day at work tomorrow, accompanied with a blank stare directed at no one.

Mule friend, this is a lesson in building endurance, I guess. But more specifically, this is a lesson in heatstroke, mental anguish, and shin-pounding boredom. There is no point to it at all other than to satisfy an irrational whim. It should be fun!

Jen T said...

I believe that when the USATF (USA Track & Field) officially certifies a race course, it is required to be at least the specified distance. In other words, an official certified 5K or marathon is allowed to be a smidge over 5K or marathon distance, but it cannot be under. Course designers throw in a tiny fudge factor overage, to make certain their courses count. So your decision to slightly overestimate the distance, rather than risk underestimating, is justified.

I do agree that the bike doesn't justify 4 significant digits, but I'll let it go. Did you sit on the bike and have Donald measure the actual wheel circumference with your body weight on the bike? That would make a difference.

Sure wish I could join you! Perhaps I could do something like this in Houston, in July. That would be even more fun than in Arkansas!

Anonymous said...

Hi Jen!

Yeah, I did everything with 60psi in the tires and 165 lbs in the saddle, centered as well as possible. Putting my weight on the bike shortened the rollout distance by about half an inch per turn or so.

And yes, you could design an even more torturous course in Houston. the best way would be to measure a much shorter course, say one half of a bridge. For me, my course is adequately torturous. I did ten laps the other day in mid-80s heat and it kicked my butt. It was my left knee more than the heat that shut me down, though. I coped with the heat surprisingly well. Summer is just starting, though!

Love ya Sis!