How to Fix a Bike Flat Tyre
Last updated: 7 September 2026
Remove the wheel, take out the tube, find the puncture, patch or replace the tube, and reassemble.
Overview
A flat tyre is the most common cycling problem. This guide covers fixing a puncture or replacing the inner tube to get you back on the road.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- First, shift your bike into the smallest gear and flip it upside down, resting it on the saddle and handlebars for stable access. For rear punctures, use the quick-release lever or spanner to loosen the wheel nuts before pulling the wheel out of the dropouts.
- Completely deflate the tyre by pressing the valve core with a small screwdriver or your fingernail. Remove the valve cap and keep it safe for later. For Presta valves, unscrew the brass nut at the top before deflating.
- Using two or three tyre levers, hook the first lever under the tyre bead and pull it over the rim edge. Insert the second lever about 10cm further along and slide it around the rim to release the bead. Repeat on the opposite side if the tyre is stubborn.
- Carefully pull out the inner tube from the tyre casing, leaving the valve for last to avoid damaging it. Gently roll the tube out, checking that it does not snag on the rim tape or spoke holes as you remove it completely.
- Partially inflate the inner tube until it takes a rounded shape. Listen closely for escaping air or pass the tube slowly past your cheek to feel for the leak. Submerge the tube in water if needed to pinpoint the exact puncture location by watching for bubbles.
- Mark the puncture with a circle of chalk or a pen, then roughen the surrounding area with the sandpaper provided in your repair kit. Apply a thin layer of vulcanising glue to the roughened rubber and wait for 60-90 seconds until the glue becomes tacky.
- Peel the backing off the patch and press it firmly over the puncture, applying pressure for at least two minutes with your thumb or the back of a spoon. Allow the patch to cure for at least 30 minutes before handling further.
- Before installing the tube, carefully run your fingers inside the tyre casing to feel for any sharp objects like glass, thorns, or wire that caused the puncture. Remove any debris found and check the tyre for damage.
- Lightly inflate the new or patched tube, just enough to give it shape, and insert it back into the tyre. Work the valve through its hole first, then tuck the rest of the tube carefully into the tyre without twisting or pinching.
- Starting opposite the valve, push the tyre bead back onto the rim using your thumbs, working around both sides evenly. Ensure the tube is not trapped between the bead and the rim. Inflate the tyre to the recommended pressure printed on the sidewall and reinstall the wheel.
Common Symptoms & Diagnostic Resolutions
Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| Tyre deflates within minutes | Pinch flat from under-inflation or multiple punctures | Check for two holes close together (snake bite). If present, replace the tube and ensure correct inflation pressure going forward. |
| Patch does not hold | Surface not properly prepared or glue not set | Re-roughen the area, apply a fresh coat of glue, wait until tacky, and press a new patch firmly with sustained pressure for 3 minutes. |
| Tyre beads will not seat evenly | Tube caught between rim and tyre bead | Deflate, push the tyre bead back into the rim centre channel, and re-inflate slowly while checking the bead line around the rim is uniform. |
| Valve stem crooked after installation | Tube twisted inside tyre | Deflate the tube, rotate it within the tyre to straighten the valve, then re-inflate while holding the valve straight with your thumb. |
Frequently Asked Questions
How do I prevent punctures?
Use puncture-resistant tyres, keep tyres inflated to the correct pressure (check the sidewall rating), and avoid riding over debris like glass or sharp stones. Regularly inspect your tyres for embedded sharp objects and replace worn tyres.
What should I carry for puncture repairs?
Carry two tyre levers, a spare inner tube, a patch kit with glue and sandpaper, a mini pump or CO2 inflator, and a small multi-tool. These items fit easily in a saddlebag or jersey pocket.
Can I fix a puncture without removing the wheel entirely?
Yes, for front wheels you can usually patch the tube in place, but it is much easier and more reliable to remove the wheel. For rear wheels, removal is recommended for full access.
How do I know which tube size I need?
The tube size is marked on the tyre sidewall, for example, 700x25c or 26x1.95. Always match the tube to your tyre size and valve type (Presta or Schrader).