Repair a punctured inner tube
Find the hole in a bicycle inner tube and apply a vulcanising patch to repair it.
Goal: Repair a punctured bicycle inner tube using a patch kit so the tyre holds air correctly.
Minimum practice time: 0.5 hours
Materials needed
- • Inner tube patch kit (patches, glue, sandpaper)
- • Tyre levers (2)
- • Bucket of water or wash bottle
- • Pen or chalk
- • Clean cloth
- • Tyre pressure gauge
- • Bicycle pump
- • Spanner or quick-release lever
Safety first
- ! Make sure the bike is stable before you start
- ! Do not over-inflate the tyre — check the sidewall for the maximum pressure
- ! Dispose of old inner tubes and used glue packaging in the bin, not on the floor
Steps12 total
- 1
Turn the bike upside down
Place the bike on its handlebars and saddle on a stable surface.
Done when:The bike stands stable and you can reach the wheel freely.
Why:Working on a stable bike prevents accidents.
- 2
Remove the wheel
Open the quick-release lever or undo the wheel nuts with a spanner. Lift the wheel out of the dropouts.
Done when:The wheel is fully removed from the frame.
Why:You cannot fix a tube while the wheel is on the bike.
- 3
Remove the tyre from the rim
Press the tyre bead inward on both sides. Use two tyre levers to pry one side of the tyre off the rim.
Done when:One side of the tyre is fully off the rim.
Why:You need to reach the inner tube inside the tyre.
- 4
Remove the inner tube
Unscrew the valve locknut. Pull the valve through the rim hole. Pull the tube gently all the way out.
Done when:The inner tube is completely removed from the tyre.
Why:You need the tube in your hands to find and fix the hole.
- 5
Find the puncture
Inflate the tube slightly until it holds shape. Hold it near your ear and slowly rotate it. Listen and feel for escaping air.
Done when:You have found the exact spot where air is escaping.
Why:You must know exactly where the hole is before patching.
- 6
Mark the puncture
Draw a small cross with a pen or chalk centred on the hole.
Done when:The puncture is clearly marked with a visible cross.
Why:The mark stays visible after you deflate the tube for patching.
- 7
Roughen the area
Rub sandpaper lightly in a circle about 4 cm wide around the hole. The rubber should look slightly dull.
Done when:The rubber surface around the hole feels slightly rough to the touch.
Why:Rough rubber holds the patch glue much better than smooth rubber.
- 8
Apply patch glue
Spread a thin, even layer of vulcanising glue over the roughened area. Wait 2 to 3 minutes until the glue feels tacky.
Done when:The glue feels slightly sticky, not wet or runny.
Why:Tacky glue bonds much more strongly than wet glue.
- 9
Apply the patch
Peel the foil backing off the patch. Centre the patch over the cross mark. Press it firmly from the centre outward. Hold for one minute.
Done when:The patch is flat with no air bubbles or lifted edges.
Why:Air will continue to escape if any edge of the patch is not sealed.
- 10
Refit the inner tube
Push the valve through the rim hole and tighten the locknut slightly. Tuck the tube evenly all the way around inside the tyre. Check there are no folds.
Done when:The tube sits flat inside the tyre with no twists or folds.
Why:A folded tube will be pinched and puncture again when inflated.
- 11
Seat the tyre on the rim
Push the tyre bead back onto the rim starting from the valve. Work around both sides with your thumbs. Do not use tyre levers for this step.
Done when:The tyre bead is fully seated inside the rim all the way around.
Why:Tyre levers can pinch and damage the repaired tube.
- 12
Inflate and test
Inflate the tyre to the pressure shown on the tyre sidewall. Check the tyre is round and even. Listen for any air leaks.
Done when:Tyre is firm, correctly round and not losing air after 10 minutes.
Why:Correct pressure gives safe grip and prevents pinch punctures.
Common mistakes to avoid
- × Not waiting for the glue to become tacky before pressing the patch
- × Forgetting to mark the hole before deflating the tube
- × Using too much glue
- × Fitting the tube back with folds or twists
- × Not checking inside the tyre for the thing that caused the puncture
Supervisor checklist
Confirm each item is completed before signing off.
- Learner located the hole before deflating
- Glue was applied and allowed to become tacky
- Patch is flat with no lifted edges
- Tube was refitted without folds
- Correct tyre pressure was reached
- Tyre held air for at least 10 minutes after inflation
Evidence required
- • Repaired tyre holds correct pressure for 24 hours
- • Supervisor signs the completed checklist
- • Photo of the finished repair
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Tick off steps, add evidence and register hours in Bloeiindex.