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Wednesday, April 4, 2012

Why do my tires leak during the winter?

By Smokey Dymny, Veteran Bicycle Mechanic and Teacher
Quadra Bike School

Yes, spring’s just about here and you’re ready to ride again. Before you pump up your tires, let’s check a few things first.

You may be asking "Why are these tires so soft when the bike sat still all winter?"

The answer is: rubber always leaks whether you are riding or not. If your tires are completely flat you may have to check the tubes for a pinch flat. Next winter hang the bicycle up or stand it upside down so it isn’t standing on the tires. The tires will still lose pressure but you can prevent tube damage.

Before you start pumping squeeze the sides of the tires together checking all around the circumference and look for cracks in the rubber. Pull out any sharp objects that may be stuck in the cracks. If the tire cracks are deep enough to show white at the bottom you are looking at the tire casing which is the inner cloth layer of the tire which gives the tire its shape, flexibility and strength. If you can see this casing you’d better replace your tire because it is worn out. It’s also worn if the sidewalls are deeply cracked or if the tire tread is worn down to the casing. If the tire isn’t worn in any of these ways then inflate it to the maximum pressure listed on the sidewall and ride.

Yet worn tires may be a good thing because you can replace them with better ones for your future rides. Many people were sold mountain bikes or fat-tired hybrids for commuting because those are the bikes people feel safer on at first. New riders often think that fat tires will be safer on the streets.

Another common misconception is that knobby tires are good for traction. Yes, they are good for traction, but only on dirt. Unless you ride through forests and fields on your way to work, you will be riding the streets on the equivalent of a tractor tire. This is causing you lots of extra effort. As a matter of fact your whole mountain bike was designed for off road riding. But don’t despair. You don’t need to switch bikes right away, just change those knobbies for something useful.

My wife’s hybrid bike had fat, 26” low knob tires and I replaced them with completely slick (smooth), high quality “Kojack” tires by Schwalbe. She was afraid that a completely slick tire would be unsafe but after just one day, she was sold. Her ride to work was faster with no extra effort. One reason is that slicks have a greater contact patch with the road.

Think about it.

A smooth tire touches the road with it’s whole surface, even if it’s only 2 square inches. A knobby tire only touches the road with the tops of the knobs on that same two inches. So the slick has better contact for traction and braking. The second reason to upgrade is that higher quality tires have a better casing (the cloth under the rubber) so they can take higher pressure. Higher pressure translates into more speed. The better tires are made with better rubber compounds, which give you increased traction when cornering and better braking too. If your safety in traffic depends on the little patches of rubber making contact with the road, why would you buy cheap tires?

If your bike was a hybrid with 700c wheels you can trade up to even narrower tires. If you had 700c tires with 32 to 35 centimeter widths, try a slick with a 25 cm width. You’ll be fairly flying down the road! Of course don’t forget to keep pumping up your new tires every week. All rubber leaks slowly. And high pressure means speed. You will also get fewer flats when your tires are hard.

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Charles Moffat is equal parts bicycle mechanic, cyclist, painter, sculptor, fantasy writer, poet, website designer and pun maker. For more details see



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