Changing a flat tire on your bicycle

Having assisted a dozen different cyclists with flat tires this summer, I found that very few experienced cyclists fully understood the process of fixing a flat. If you plan to ride your bicycle beyond the proximity of your immediate neighborhood you need to be prepared for a flat tire.

OK, you are flying down the road and a tire suddenly goes flat. Hopefully, you are not on a downhill stretch, but if you are speeding downhill, apply the brake of the wheel on which the tire is not flatting out. Keep the bike perpendicular and slow down with a gentle application of the one brake. First priority is to get clear of the roadway and find a safe, suitable location to perform repairs. Presumably, you maintain a constant inventory of necessities, (2) tire tools and (2) tubes in your seat bag, along with (2-3) Co2 cartridges. A mini-air pump is a wise addition which can be clipped to your water bottle cage.

If you are dealing with a flat on the rear wheel, shift to the smallest cog before you remove the wheel. Open the caliper release lever to spread the brake pads farther apart, open the quick release lever on the left side of the skewer, loosen the axel nut on the right side until the wheel is free to drop-out from the frame/fork.

Before you do anything else, inspect the flat tire to identify the cause of the flat and remove any objects protruding from the center ridge or the sidewalls.

• ·        Working your way around the tire, push against the sidewalls till you feel the ‘bead’ break away from the rim.
• ·        Insert the tip of the first tire lever under the bead and hook the opposite end around a spoke. Then insert the tip of the second tire lever under the bead about 4” away from the first tire lever. Now, pull that second lever along the rim, sliding the tire’s bead over one side of the rim all the way around the wheel.
• ·        Pull the tube out smoothly and search to identify the cause of the flat. A hole on the rim-side of the tube may be indicative of the need to replace the rim tape or address a spoke or rough surface on the edge of a spoke hole. A hole on the road-side of the tube would suggest a thorn or nail was the cause. A double hole would suggest “Snake-bite” caused by impact on a chuck-hole or a railroad track. A small cut would suggest a piece of glass was the cause. If necessary, put a small amount of air in the flat tube to help locate the puncture location.
• ·        Do not be impatient. It is important to identify the source of insult before prematurely inserting, and trashing another good tube.
• ·        Match the tube’s puncture location with the tire to identify any object remaining in the tire. Observe the outside of the tire as well as the inside surface. Additionally, cautiously slide your fingers around the inside of the tire in search of objects that might puncture the new tube.
• ·        Put a very small amount of air in the new tube, then insert its valve into the rim hole and slide the tube into the tire all the way around the wheel. Simultaneously work the tire back onto the rim as you place the tube inside the tire. The last few inches may require significant manipulation depending on your tire bead and/or rim model.
• ·        Using your thumbs, push the tire bead back onto the rim all the way around the wheel. Ideally you can complete this task with just your hands. If tire levers are required, use extreme care to avoid pinching the new tube.
• ·        Now, pushing with your thumbs, work your way around the tire to insure that the tire is seated evenly and that the tube is not protruding between the tire’s bead and the rim.
• ·        Add some air and re-inspect the bead for a proper fit before fully inflating the tire to the recommended tire pressure found on the sidewall.
• ·        Replace the wheel in the frame/fork dropouts, close the caliper release lever, and tighten the wheel’s quick release lever with one hand while holding the wheel centered between the brake pads with the other hand.
• ·        Spin the wheel to verify that the rim is properly positioned between the brake pads. Apply the brake and visually confirm the proper clearance remains as set.
• ·        Ride cautiously for a few minutes to assess your success. If you have pinched the tube between the tire bead and the rim you may experience a loud explosion, like a gun shot, as the tube blows-out.

Besides offering a smoother, more efficient ride, properly inflated tires are less prone to flatting-out. Before every ride take a few minutes to top-off your tires’ air pressure and perform a quick-check to identify potential tire/wheel/brake problems. It is not uncommon for tires to lose 5-10 psi overnight or between rides. Prioritizing your ABC Quick-check may prevent a “garage flat” from making you too late for the ride start.

Properly inflated tires should last approximately 3,000-5,000 miles. Regardless of miles ridden, tires should be replaced if there are cuts or other breaks in the integrity of the tread or sidewalls. Rim tape should be replaced on a yearly or bi-yearly basis, or when damaged.

Ian Seecof is the Safety & Education Chair for the Central Indiana Bicycling Association. If you have concerns regarding safe cycling, touring, commuting or any other cycling related questions he can be reached at safety@cibaride.org.