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How to Fix a Flat Tire

Learning how to fix your own flats can make your rides less stressful, and make you more confident when on a ride.
Top image caption: Bicycle wheel beside rider's legs

Published on October 20, 2016

Tools you need (pictured above)

  • A pump
  • A patch kit
  • A multi tool
  • Tire levers
  • Glue for patching
  • A spare tube
  • A tire boot
  • A wrench
  • A rim strip

How to position your bike

You can work on your bike upright, upside down, or in a repair stand. Upside down or in a repair stand will allow you to pedal and shift through the gears to make sure everything is in working order.

Fixing the flat

  1. Open the brakes.

    Most bikes have some method of quickly releasing the brakes.

  2. Remove the wheel from the bike.

    You’ll need to loosen the axle nuts or open the quick release skewer. If it is a rear wheel that has the flat, have the chain on the smallest cog and smallest chain ring for the greatest amount of chain slack.

  3. Move the derailleur back and out of the way of the axle.

  4. Pull the chain away from the cogs.

    Pull your wheel to the opposite side of the chain to remove it completely.

  5. If your tire still has some air in it, deflate it the rest of the way.

    You can push on the pin inside the valve to release the air (or unscrew and push on the pin if it is a Presta tube – not pictured).

  6. Using two tire levers, place the spoon-like end under the tire bead.

    Lift the tire bead away from the rim and hook one tire lever onto the spoke.

  7. Slide the other tire lever around the rim, removing the bead from the rim.

  8. Place the wheel on ground.

    Then, pull up on the tire, pull over its edge the side of the rim, and push down.

  9. Remove the tube from your tire and pump more air into it.

    Hold the tube next to your cheek and feel and listen for air to find the hole.

    Once you find the hole, circle it with a piece of chalk. Check to see if the hole is on your tube rim-side (the same side as the valve) or facing the tire.

    These things will help you identify the cause of your flat and are key to preventing them in the future:

    • A tiny hole is likely caused by glass or a staple
    • A large gash in your tube is usually caused by the tire blowing off the rim
    • Two small holes or slits next to each other indicate a pinch flat, which is often caused by under-inflation and potholes​
    1. If your tube’s hole is on the tire side:

      Inspect the tire while lightly feeling for pointy debris inside the tire.

      Hold the tire up to the light if you can’t find anything with your fingers. If you can see daylight through your tire, it may be time for a new one.

      Remove debris. Be careful of pricking or cutting your fingers on any sharp objects embedded in the tire – if you find something this is likely the cause of a flat!

    2. If your tube’s hole is on the rim side:

      Inspect your rim to make sure your rim strip is fully covering your spoke nipples and isn’t damaged.

      Are the spokes poking out higher than the nipples? This is a frequent cause of flats.

      Find the seam of your rim (directly opposite your valve hole). Is the seam rough? It may need to be sanded flat if there is a rough edge.

  10. Replacing your tube (patching instructions below, but not pictured)

    Go to your friendly neighbourhood bike shop and buy a tube. You can tell what size tube you need by checking the side of your tire. There should be series of numbers stamped on the tire (e.g. 700 x 23c; 26 x 1.75) that will tell you the size. When in doubt, bring your tire and wheel with you to the shop to find a tube. Be sure to note what your valve looks like! There are two common types, and your rim is only drilled for one. Presta is the skinny one and Schrader is the fatter one that looks like a car tire valve.

  11. Inflate your new tube.

    Put just enough air in that it holds shape. This will keep it from bunching up as you re-mount it inside the tire.

  12. Put your tube into your tire.

    Have the logo of the tire next to the valve: this allows for better orientation if you are trying to locate the source of the puncture.

  13. Time to remount your tire and tube!

    Start by putting your valve into your valve hole located on your rim, and then put one side of the tire back on the wheel. In most cases, it will be extremely difficult to get your tire on if try to put both sides on at the same time. Be sure your valve stays perpendicular to the rim during this process.

  14. Mount the other side of the tire.

    Do this by pressing your thumbs into the sidewall of the tire and moving them together around the wheel. When the going gets tough at the end, move your thumbs closer together, and press on the part of the tire that is almost on. You can also let a bit of air out of the tube at this point if needed.

  15. Find your recommended inflation pressure.

    This may read as MIN – MAX PSI. Find the number on the gauge of your floor pump and inflate to maximum pressure. Keeping your tires inflated to maximum pressure will extend the life of your tires and rims.

  16. Time to put your wheel back in!

    Pull the chain down and wrap it around your smallest cog on your freewheel/cassette.

    Pull your derailleur down and back to allow your axle to move towards your dropouts.

    Fully seat your axle in your drop outs and tighten your axle nuts or close your quick release, depending on your bike.

  17. Don’t forget to reconnect your brakes!

  18. Second to last step:

    Flip your bike right-side up or take it out of the stand, lift it a few inches off the ground and drop it. Does it sound like anything is rattling? If you hear a rattle, something is probably loose that needs tightening.

  19. Last but not least - take it for a ride!

    Take your bike for a test ride! Problems are easier to find when you’re on the bike. A rider’s weight makes things act differently than they do in the stand.

Worried you screwed something up? Not sure how to do any of this? Pretty sure what we mean but need some clarity? Come visit Bike Works at Evergreen Brick Works and we’ll go through this with you step by step and answer any questions you may have.

Tube Patching (Read All Steps Carefully Before Proceeding):

  1. Locate the puncture and circle it with a pen or mark it with your nail.
  2. Use the emery cloth in your patch kit to remove the release agent of the tube around the hole.  Remember to keep track of where the hole is.  Ideally you want that to be in the centre of your patch. 
  3. Choose the right size patch from your kit and apply some glue to the tube.  Make sure the that glue area is bigger than the patch area
  4. Allow the glue to dry until the sheen is gone (a couple minutes)
  5. Peel off the foil backing from the patch and apply the patch, leave clear cover on.
  6. Apply pressure and leave clear backing on.
  7. Let it cure for 24 hours before using a patched tube.