Bad air

Last week I got an email seeking my insight from Chris, a [the only?] loyal Hooptedoodle reader.  He had just done his first ride on a single speed 29er and he wanted to know why he had to get off and walk up a few sections that he normally has no problem with.  In fact, he had set a personal record on the same trail only the week before. 

Actually, he had two questions:  First, are all those riders singing the praises of 29ers and single speeds certifiable crack pots?  And second, is he just a wuss?   I don’t think the two are mutually exclusive. 

You can read his whole email here:  Download dear_chad.doc.   

The obvious answers to Chris’s questions are that no, he is not a wuss and no, single speeders and 29er riders are not wing nuts.  First of all, he changed too many variables in his experiment.  If he wanted to know how riding a 29er compares to riding a bike with small wheels [For the record, I now refer to 29 inch wheels as ‘standard size wheels’ and 26 inch wheels as ‘small wheels’], then he should have ridden a standard size bike with gears. 

And if he wanted to know how he would do on a single speed he should have ridden one with small wheels like his other mountain bike.   Note to Chris:  Ask your scientist wife to give you a lesson on experiment design. 

The next obvious answer is that there is a technique to riding single speeds, regardless of wheel size, that only comes with practice.  Resting on the go is more difficult than on a geared bike.  Line selection is more crucial because you’ve got to maintain your momentum.  And if you’ve got a rigid fork it adds to your fatigue.  With all that going against them, it’s no wonder why single speeders only do two laps at the local mountain bike races. 

Like I said, those are the obvious answers, but there is a more insidious answer that may explain why Chris had such an embarrassing ride. 

Chris set his personal record on October 22nd.  His single speed 29er experiment occurred the morning of October 31st.  Those of you in Salt Lake Valley might recall that there was a strong inversion over the valley during that week—we’ve got another strong one this week.  An inversion is a meteorological term used to describe a mass of cold air trapped beneath a mass of hot air.  It’s 'inverted' because normally the temperature drops as the altitude increases. 

In much the same way that oil and water don’t mix, the cold air trapped below doesn’t mix with the hot air above it during an inversion.   And since there is no mixing, anything people on the ground put into the air during an inversion doesn’t get diluted.  The result is elevated levels of pollution, hacking coughs, scratchy eyes, asthma attacks, and, just maybe, diminished athletic performance. 

I checked the pollution levels in Salt Lake’s air for the days Chris did his rides, and sure enough, the concentration of PM2.5 on the morning of the 31st was about twice as high on the morning of the 22nd. PM2.5 means particulate matter, basically dust, below 2.5 microns in diameter.    Particles smaller than about 1 micron are small enough to work their way deep into our lungs, where they tend to stick.  It can take a few days for our lungs to clean them out (think phlegm, or what cyclists call lung oysters).  In the meantime, any chemicals on the surface of those dust particles have had plenty of time to be adsorbed into the bloodstream.   

So the good news is that Chris is not a wuss, single speeders are not crazy, and standard size 29 inch wheels are a good thing.  The bad news is that Chris may have damaged his lungs. 

So what’s a cyclist to do?  Driving up the canyon above the inversion exacerbates the pollution problem, so that’s not a good solution.  What I suggest is a quick check of the current ambient air quality conditions on the Utah Division of Air Quality website [click on Trend Charts], where they have up-to-the-hour data for Salt Lake, Davis, Cache, Weber and Utah Counties.  In the wintertime pay attention to the graph on top, PM2.5.  In the summer, the second graph, Ozone, is the one to watch.  In both cases, the 1-hr lines are more representative of current conditions.   

When concentrations are high, you might consider turning the intensity of your workout down a notch or two.  You might also consider bicycle commuting so we won't have these problems in the future. 

Comments

[jruss]

1. You have at least two loyal readers.
2. People who ride single speeds are certifiable crack pots.
3. Thank you for the inversion lesson.
4. I love anytime the word "exacerbate" is used in a dialogue.
5. I just referenced you for the "holy trinity of mountain biking." Thank you.

[Chris]

wow Chad, that is a pretty insightful response. I hadn't even thought about the air issue, even though I probably should have since air quality in general has been on my mind a lot more than usual lately.

I will also give both 29ers and single speeds a better chance sometime soon. Thanks!

[Babers]

The only loyal reader????? Don't count Babers out....