BikeTechReview

A few years back, I wrote this sucker:

http://www.biketechreview.com/aerodynamics/uncertainty.htm

whoa, that's probably the third time I've used partial differentiation in a setting outside of academia!!! :-)

To be honest, my experience as a consumer product development engineer in the bike biz (2+ years) and the golf biz (coming up on 10 years now... holy cow!) is much more caveman based than what doing partial differentiation might suggest.

Granted, the tools/toys I get to play with in the golf biz these days are a couple steps above the beer cans and bits of string I got to use in the labs I had at my disposal while in the bike biz... ;-) ...but, still, I think that even with the fancy tools I get to use these days, I find myself relying on my caveman instincts when it comes to judging "goodness" of data that so many of the high tech gadgets can spit out.

Y'know, folks will have to assess for me how well their methodology and instrumentation they have used can repeat a given measurement/setup condition within a day and across days before it gets my attention. For example, with a pedaling rider in the tunnel, I have seen things (axial force) repeat to within less than 10 grams...but I've also seen things not repeat so well. Over the years, and more than a thousand runs with pedaling riders, I've grown to know how much I can trust what the tunnel is telling me...and that knowledge drives the way I choose to test.

The same kind of familiarity with repeatability is helpful when placing "equipment only" wind tunnel test #'s into context.

Not sure where I'm going with all of this, other than, I don't think folks think about experimental uncertainty enough - especially when it comes to doing field tests with a power meter. "Subjective validation" of these data might kick in if you wind up getting the answer you were more or less looking for:



Anyway, speaking of repeatability, I was checking out some additional repeat data I have on a specialized trispoke (the same one linked to in the partial derivative link above) today. I've tested this exact wheel/tire combination in a couple tunnels (texas a&m and lswt.com). I've tested the trispoke in the san diego wind tunnel eight times since 2005 (yeah, that would be over a four year time period) at a beta=0 flow condition.

What was the standard deviation of the multiple runs over that 4 year period for the exact same wheel/tire setup? 3.8 grams of axial force at 30mph. That seems pretty good to me. What do you think? What can the other tunnels do over that same four year time period in terms of "equipment only" repeatability?

So, yeah, that std deviation tells me about how well I can trust the data coming out of the facility here in San Diego over time. My caveman instincts are comfortable with these data out of San Diego! :-)

I don't know if you've been watching any of the new Ken Burns documentary on the US National Parks or not...but if you haven't, I'd recommend you check it out.

The imagery, in HD, is something to behold; but what really is remarkable to me is the writing. The words, as spoken, provide a link to my past and tease out some powerful emotions stowed away inside of me.

Everyone has their recollection of their "family vacations" of their youth; and, whether you are like the Griswolds, or the Willett's - there will undoubtedly be some vivid memories founded in those experiences.

For me, watching Burns' film (I just got done watching an episode a few minutes ago...) put me back in time. I can remember one of our treks in a 198X chevy econoline conversion van where we hit yellowstone, teton, mesa verde, among other national parks. I'm pretty sure we were going to a bike race(s), but nonetheless, I hold those national parks experiences near and dear...

yeah, I'd have to say that most of my fondest/most vivid memories have an element of nature that are connected, or attached to those experiences. Some of them involve the national parks as mentioned above, but most of them fall outside that realm. The commonality, though, is nature...the elements...I guess there is something to be said for what nature represents (to me, anyway) in those situations. It's something that cannot be controlled. It is something that is just endured. Persevered. Survived.

Y'know, adventures suck while you are having them...seek out those adventures, eh?

One of the most epic bike rides I ever did was on a mountain bike (a fuji suncrest rigid deal I bought in 1990 for commuting to class...) - it was the dead of winter in the inland northwest. I forget the details, but I remember the feelings. The sensations. The two guys I did that ride with.

What's your most epic ride that has an element of "nature" tied to that memory?

Oh geez, now I'm just ramblin'! :-) Let's move on...

Pink:

Yeah, in case you missed it, October is breast cancer awareness month. It's pretty amazing to wrap your melon around how many people are personally touched by breast cancer... My family has been touched by it. My friends have been touched by it.

In order to raise awareness, October is the month to sport your pink! If you have any concerns of "manly-ness" and pink, take heart that the NFL is going pink!

Here's my way of doing my part to raise awareness during breast cancer awareness month...y'know, this is a bike related blog and all! ;-)



That's some frilly pink, eh?! That thing is so awesome - I was able to cram a spare tube, a multi-wrench and a couple co2 cartridges into this compact bag...more importantly, though, I get lots of weird looks and it's a great conversation starter. A great way to raise awareness, IOW!

I met up with the guy who is responsible for that bag at interbike a couple weeks ago, and he kicked down this bag for my wife...but I'm sportin' this bag for the month of october...at least! :-)

What are you doing, via "pink", to raise awareness this month?

peace,

-k