Thursday, May 31, 2007

The Data Crunching Begins...



This is my power data from the Hillclimb at Kern. I use a *gasp* ibike to collect this data. It's not as good as a powertap...but a heck of a lot cheaper, and still a lot of fun. I first bought it because it uses MEMS accelerometers and pressure sensors, and that is a technology I still work on...so it's nice to see it ending up in products! How it works is it has microaccelerometers and tilt sensors to measure the acceleration and the road grade. It also has a pressure sensor which measures the wind forces acting against you, as well as you calibrate it to account for the frictional losses in your bike/tires/etc. Then it uses the equation P=F*v (power=force times velocity--all vectors of course) and by measuring speed on a wheel pickup, and remembering Newtons Law (F=ma (also vectors)), you can calculate power. Now, it has its good and its bad, but mostly I like it, and it is a MUCH cheaper alternative to a PowerTap.

Anyway, I took data in all my races at Kern except for the TT, as I didn't want to re-mount the thing between races. I didn't have time to go into the data set and delete the downhill part of this file...so the average power isn't really that meaningful...from a quick look at the graph it looks like the average power for me on this climb hovered a tad under 200. Not bad for me, considering Im a lightweight (a tad under 130). I got what I got...although happily I have improved over the training season, so that's all good!

Of course I don't like to get too invovled with the numbers...as it then becomes too much like work and not enough like fun...but sometimes it's neat to look at and look for improvement, etc. :-) And sometimes its fun to look at the really fun stuff like the 900W sprint at the end of a brutal race...to relive the fun.

Ciao!

9 comments:

Chris said...

Of course it is all vector. DUH!

:)

Kimberly (aka. DrKim) said...

I put that to make fun of the funny captions that OV put on the pictures of me from the Kern TT...
-inside joke that you can figure out from looking at his Kern photos :-)

dr-nitro said...

geek

Kimberly (aka. DrKim) said...

yup. i admit it...
i have a geeky side.
but I have 2 cool dogs :-)

dr-nitro said...

Yeah, well I teach kids about heteroskedacity, among other geeky things, so I know a bit about geekness. But yeah, me dog, I hope, provides balance. The bikes do too, but I'm afraid that I'm spoiling that by strapping my Garmin to the bars. Numbers, ooh, numbers.

Kimberly (aka. DrKim) said...

i have never heard of heteroskedacity...just shows you how geeky I am (not). :-)

tape works wonders for covering up the data....and letting the bike be just itself.

dr-nitro said...

It's non-constant error variance, which leads OLS, and other regression estimators, to be inefficient. Duh.

Sincerely,

Geek

CyclistRick said...

Geekfest city, and I'm not even at work! (I work at a startup software company, where the geek factor is off the charts). Unfortunately, I did understand what Dr. Nitro was talking about ... a legacy of my deep immersion into the world of test design and statistical analysis back in the old days ;-)

Numbers are good, but I like to listen to the old body. It tells me a lot, numbers just confirm. But I do enjoy playing with devices and their output :-)

Kimberly (aka. DrKim) said...

ok. so we're just a bunch of bike racing geeks! And now I know what heteroskedacity is! (I had only one statistics class and it was a LOOOONG time ago). Other math, though...well I know too much for my own good, most definitely...