Bike Maintenance

Puncture Repair

by Paul Foley

Cyclist repairs looks for a hole in his tube
photo by Xtnsgo

If you are new to cycling, and you have never fixed a puncture before in your life, it’s highly recommended to practice changing tubes a few times at home before you hit the road. You will be more prepared for a flat when it does happen, and you will be aware of all the possible pitfalls.

  • Open the quick-release lever on the brake caliper. If the puncture is on the rear wheel, shift the chain into the smallest cassette cog to make the job easier. Open the quick release lever of the hub and take off the wheel. Keep forward pressure against the spring of the rear derailleur as you remove the wheel. (If your bike is an old model, you may need a 14mm or 15mm spanner to open the axle nuts.)
  • Remove the tyre completely from the rim and pull out the inner tube. By removing the tyre completely from the rim, you can fully inspect the inside of the tyre for foreign material, or any thorns being pushed through from the outside. Also check the condition and position of the rim-tape on the wheel. Any spoke nipples showing through could have been the cause of the flat. This is where the roll of electrical tape may be needed to get you home.
  • Put a little air in the new tube to give it shape. Place it into the tyre. Some tyres are directional, so check the tyre sidewall for an arrow before mounting onto the wheel.  The arrow should face in the direction that the wheel will rotate in. (Beware if working on a bike that’s turned upside down – the arrow will face the opposite way when the bike is upright again!)
    If installing a new tyre, it’s recommended to put in a new inner tube as you’re at it (especially if the old tube has a patch or two on it). Doing this adds in a little reliability. Also, sprinkle talcum powder on the new tube, and rub it in. This makes it easier to mount the tyre, reduces the risk of pinching the new tube, and prolongs the life of the new tube.
  • When mounting the tyre onto the rim, finish one side completely before starting the other side. Begin at the valve end and work away from the valve. When most of the tyre is mounted, be careful not to pinch your new tube between the tyre and the rim.
  • For the very last section of tyre that just won’t go on, try leaving a little air out of the tube. Try squeezing the tyre lever into the area between the outside of the tyre and the inside of the rim. Do this coming from the direction of the section of tyre already seated. This will force the tyre to hook in over the rim. If the last section of tyre is still being stubborn, pull the troublesome side of the tyre back out. Start from the valve end again, but this time pay more attention to keeping tension on the tyre the whole way around. This will mean you have more slack to play with by the time you get to the opposite end.
  • With the tyre fully on, ensure that the valve and tube are seated correctly. To do this, with the tyre still mostly deflated, push the head of the valve right in towards the rim hole. Then pull it back out again. By doing this you push the tube away from the rim inside the tyre. (If the tube had been caught between the tyre and the rim (at the valve area), it is now free.) Next check that the valve is exactly perpendicular to the rim. If it’s not exactly 90˚, it will mean that the tube will be under strain when fully pumped, and you will likely end up with a hole in the tube near the valve. (An impossible place to put a patch).
  • As you pump the tyre, check frequently that there are no bulges forming due to the tyre unhooking from the rim. If something doesn’t look right, let the air back out, work the tyre back into the correct position, and pump again.
  • If you’re having a bad day and you are on your 3rd puncture, you may need to patch a used tube. Pump the punctured tube. Listen for hissing, or use a sensitive part of the face such as the cheek or top lip to feel for escaping air. Water can be used if available. Escaping air will cause bubbles to form at the hole.
    There is one thing to note when applying the vulcanizing rubber solution paste: On a very hot day it’s best to leave the paste open to the air for a little while, before placing the repair patch over it. This ensures that it’s tacky, and the patch will stick perfectly on the first attempt.
  • When mounting the wheel back on the bike, you may need to leave a little air back out of the tyre to enable it to clear the brake blocks. Only do this after making sure that you have freed up all the available cable using the barrel adjuster and quick release brake lever.
  • If the puncture was on the rear wheel, you will once again need to apply pressure against the rear derailleur cage tension spring in order to get the wheel back on. (Make sure the chain ends up on the top side of the cassette). Re-close the quick release hub lever, when you can see that the wheel is central.
  • Reclose the quick-release lever on the brake caliper, which will bring the pads back in towards the rim breaking surface. Before you cycle off, make sure the brake pads contact the rim correctly. Re-position the wheel if the brake block makes any contact with the sidewall of the tyre.

 Quick Release Lever

  • Regarding the quick release lever of the hub, there are different preferences for its closing position. The lever itself normally goes on the side of the bike opposite to the chain. However, the direction that the lever faces in when closed can vary. Whichever one you use, make sure that the end of the lever is tucked away, to prevent accidental opening (such as from the pedal of a fellow rider).