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The Critical Nature of Bicycle Tire Pressure
Ian Murray
Forget everything you’ve heard about the “ride” of a bike made of steel, made of titanium, of aluminum o
r carbon. Forget the theories spewed forth on mixed frame materials where carbon seat and chain stays
are morphed into a metal bike. Forget
t
h
e impas
sioned arguments of a carbon seat post being of some
great difference to an aluminum seat post. Forget it all! If you want more comfort or greater responsiveness or some other change in your bikes handling or “feel” – look to tire pressure first.
Listed on the side wall of your tires there is a maximum tire pressure allowed for your tire. It’s diffe
rent for many tires so search for the hard-to-read print in good light and find the max and let this be your starting point.
Super, Super Soft
Some folks pay little attention to their pressure. The air, over time, seeps out of all tires and when the max might be 110psi they roll off for their ride at around 70psi. At 70psi a typical road bike tire will feel pretty hard; if you try and push your thumb down into the tire it’ll feel like a rock. But at that low pressure there is a greater contact patch (the amount of rubber meeting the road) and more rolling resistance – all this means SLOW! Also, the risk of a pinch flat is far greater at low pressure (a pinch flat is when you hit a sharp edge and the tube is “pinched” between said edge and the rim). As far as comfort goes, an extremely soft tire will bob around a bit and even bottom out on bumps causing a rougher ride. The most dangerous issue is that an under inflated tire could roll off the rim in a descending, fast corner.
Properly Inflated
By maintaining proper inflation, and let’s define that as 5-10psi below the max, the rider gets the best out of the tire and the bike. Pinch flats are less likely, rolling resistance is fairly marginal, the ride is comfortable and the bike performs well. If comfort is more important that speed then a few less pounds of pressure can help create that feeling.
Beyond the Max
Once you inflate a tire beyond the maximum pressure issues can and will arise. The ride gets rougher. There is a greater risk of tire damage from road hazards (side walls tear easier, sharp rocks can blister the tire). The bike will likely bounce around a bit and traction can be lost. And lastly, a severe temperature increase can cause an overly inflated tube to explode.
The best way to control your bike’s “feel” and performance on the road is to purchase a reputable floor pump with an accurate pressure gauge. Keep in mind that most bikes are sold with a Presta valve or a Schrader valve and the pump must match. Check your tire pressure before every ride and begin to assess the feel of your bike on the road at different tire pressures.
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