Thursday, May 8, 2008


Local television news has a story about filling car tires with 100% nitrogen. Allegedly, nitrogen doesn't leak down as quickly so tires stay at a higher pressure for a longer period of time. This increases gas mileage. There's also a claim that nitrogen extends the life of the tire, but I suspect that if they're properly inflated – regardless of the gases inside them – they'll last longer too.

For a fleet operation, filling tires with nitrogen probably makes sense. If the claimed 3% increase in gas mileage is true, it translates into large cash savings. But the local business offering this service charges $39.95 to fill four tires. From where I sit, that may not be a cost-effective savings for consumers.

There's a solution, of course. I use a cheaper mixture that contains only 80% nitrogen in both car tires and bicycle tires. The only drawback is that I have to check the pressure regularly. That means using a pressure gauge on the car tires about once a week. But for a bicycle, the pressure has to be checked before every ride.

That brings us to the ABC Quick check. (You didn't think I'd skip a BikeEd moment, did you?) A is for air. Check your tire pressure before every ride. Yes, it reduces rolling resistance, but it also reduces the chance of a pinch flat. Spin you wheels and look for tire cuts or a rim wobble that could indicate a loose or broken spoke. B is for brakes. Squeeze the brake lever and ensure that there's a fingers width of space between the lever and the handlebar. C is for the crank and chain. Try to move the crank arms in and out, feeling for any looseness. Feel for a loose pedal, and see that the chain is in place. Q is for quick releases. Get in the habit of putting them in the same position all the time so you can tell at a glance if they've been moved. Returning to C a moment, when you first start out pedal gently to ensure that the chain is in place properly and no one has tampered with your derailleur levers, particularly if the bike was parked outside in a public place.

There are some costs associated with ignoring the ABC Quick check. Once, someone who looks remarkably like me fixed a flat tire, then pushed off down a hill. hadn't closed the brake release lever, so the caliper barely touched the rim. Naturally, the lever went all the way to the handlebar and he discovered the brake was pitifully ineffective. Doing the ABC Quick check would have prevented this mishap.

Another time, this same rider had a rear quick release partly open. The wheel was installed in an old frame with horizontal frame ends. When he stood to power away from a stop light, the wheel popped out and tacoed. While it's possible to straighten a wheel by supporting it on a curb and forcing the rim back into alignment, it's not a practice I recommend. Some of the neighborhood kids learned a wide variety of new and exciting words that day.

(Snark alert)

Here's a fitness idea that would also save money for big fleet operators, like cities that have a large number of police cars – get cops to check their air pressure at the beginning of each shift, and give them a bicycle pump for inflation. It's a win-win situation! Proper tire inflation leads to improved gas mileage and increased tire life. And as a side benefit, we get physically fit police officers with fewer health problems. (Except for TCSO who would need extensive training in how to use a bicycle pump in the first place.) As a taxpayer, I'm 100% behind this idea!

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