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Repairing Flats

Now that all of you are carrying the essential tools for on-the-trail repairs, I’ll cover the most frequent of problems: flats.

The most common causes of flats are: sharp objects (glass, staples, thorns) penetrating through the tire and puncturing the tube; hitting an object (rock, curb, log) hard enough to flatten the tire and tube against the rim and causing a “pinch flat” and; a rupture of the tire causing the tube to squeeze out and “blow”.

Whenever your tire goes flat, stop riding on it immediately – you don’t want to cause any further damage to the tire or rim.

If you plan to replace the tube, then the wheel must first be removed from the bike. Next, mark the tire near the stem to make it easier to find where the object penetrated the tire. Let out any remaining air from the tube and then use your tire levers to pry the tire over the rim. Slide the levers around the rim to pull the rest of the tire over. Pull out the tube and locate the puncture by partially inflating the tube and listening or feeling for air escaping. Once found, align it with the tire to find out where the tire was punctured and remove any object still remaining in the tire.

Roughen the surface of the tube around the puncture with sandpaper or rough metal and then apply contact cement to the area slightly larger in size than the patch to be used. Allow the cement to dry (5 to 10 mins.) and then apply the patch firmly to the area. Inflate the tire slightly to make it easier to install back on the rim.

Replace one side of the tire bead on the rim and then slip the tube into the tire and insert the valve stem through the hole in the rim. Now slide the other side of the tire bead over the rim. Sliding the final section of the tire over the rim is often difficult – avoid using the tire levers – they can pinch the tube and cause another puncture. Once the tire is on the rim, work your way around the tire to make sure the tube is properly in place and won’t be pinched between the tire and the rim when inflating.

Install the tire back on the bike and, using a pump or CO2 inflater, fill the tube to the recommended pressure.

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