Diagnosing a Flat Tire

Consider these scenarios:

1. You finally decide to dig your dusty old 10-speed out of the back of the garage, and go for a ride. You could use the exercise, and after all, it is a beautiful day. Imagining the breeze in your face, just before you mount, you look down to find both tires flat. How could that be? You haven't ridden the thing in five years--spiders have gotten more use of your bike than you have!

2. You are riding your $900 aluminum frame mountain bike with tires made to glide like a ballerina through the worst mud imaginable...along a smooth, paved road of all places. You look up to wave at a friend, and don't see what you have run over. The next thing you hear is Pssffffssshhhh!, and your front tire is as flat as Kansas. What made it flat...and can you repair it in time for your trail ride this afternoon?

Many things can deflate or flatten a bike tire. The rubber is not as thick as a car tire, and the tube that holds the air is even thinner. Before assuming anything, and before carrying your bike to a shop that charges by the hour for labor, there are ways you can diagnose the cause of your tire flat.

Possible causes

Many things can make a tire flat. Tacks, glass, a leaky valve stem, over-inflation, an ice pick wielded in a malicious prank and time are just a few of the possible things that could make a tire go flat. It makes more sense to consider the various types of flat tires, as this is what you will have to consider as you decide to repair or replace the tube (and possibly tire) that are flat. So, here are some common flat tire types:

• Puncture - a hole caused by something sharp
• Abrasion - a hole worn through the tire and tube by rubbing
• Rupture - the ever-famous "blow out"
• Leak - seepage of air, often through the valve, over time