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Monday, July 20, 2009

Self-Healing Bicycle Tires

I find it funny that often inventions that have a really positive impact on my life come from completely unexpected places. The latest example of this is self-healing tubeless bicycle tires. I'm not what you would call an avid bicyclist, but I probably ride around 1,000 miles in a given year, nearly all of that on a mountain bike.

The Southwestern United States is infested with the goathead thorn (Tribulus terrestris). These thorns are intensely sharp and hard and can penetrate just about anything that you could make a bicycle tire out of including kevlar and steel belts. As a result, for most bicyclists out here, even (or especially) mountain bicyclists with their heavy duty tires, frequent flats are an inescapable part of life.

Or so I thought until a guy at the bicycle shop recommended (and then installed) a kit that turns regular tires and rims into self-healing tubeless tires. Basically, a special rim strip is installed, the tube is removed and discarded (or saved for an emergency), and a liquid sealant is added to the tire. The liquid sealant is distributed all through the outside of the tire while the bicycle is being ridden because of the force due to the rotation of the wheel. When something penetrates the tire, the sealant is forced into the hole by the tire's air pressure, and immediately heals the tire.

The most impressive recovery was when I somehow managed to get more than 10 goathead thorns in both my front and rear tires at the same time (it looked very much like the picture above). I only ever carry one spare tube, I didn't have ten patches left, and I was riding alone, so it would've been a long, long walk home if I had still been using tubes. But I just pulled all of the thorns out of the tires, the holes bubbled for 10 seconds or so then stopped, I got back on the bike, and rode off with no loss of pressure and no problems.


I have to admit that I particularly like the philosophy of the approach1. The alternative of trying to design impregnable super tires seems rigid and Statist to me. In that case you have to foresee everything that can make a flat and design solutions to protect against them. You end up with somewhat better protection against flats than standard tires, but at higher cost and lower performance (such tires tend to be heavier and more rigid so they don't grip as well). And such tires still are susceptible to flats from goatheads.

On the other hand, Self-Healing Bicycle Tires are a Resilient Approach. Instead of trying to prevent a situation, allow the damage to happen and then recover quickly. It doesn't matter if the damage is from a 3 inch diamond spike or a piece of glass or a tiny sliver or whatever.

Recover and just keep truckin'.

1Note that this particular approach is apparently not for everybody as shown by a few of the reviewers.


erp said...

One less thing to worry about. Happy Trails!

Hey Skipper said...

I. Hate. Goat Head. Thorns.

Even now, 25 years after riding where they are plentiful.

Harry Eagar said...

As Jason pointed out, you have to also be able to predict what happens during recovery.

Fewer flats v. occasionally being maimed or killed? Which to choose?

(tick, tick, tick, tick)

I'm thinking, I'm thinking.

Bret said...

The more flats I get, the less I ride. The less I ride, the fatter I get. The fatter I get, the higher the likelihood of heart attack which is pretty much the equivalent of maimed or killed.

Also, I personally don't ride fast enough to be maimed or killed even if the tire fell off and I was thrown from the bike.

So for me, clearly, fewer flats is the choice.