How to Fix a Bicycle Puncture

Support the bicycle securely. For a rear wheel with derailleur gears, shift to the smallest rear sprocket. Open rim brakes if necessary, release the axle according to the manufacturer's instructions and remove the wheel. Do not squeeze hydraulic disc-brake levers with the wheel removed. Motor wheels and hub gears require their own removal instructions.

Remove the valve cap. For Presta valves, unscrew the small tip nut and press the tip. For Schrader valves, press the centre pin. Let all air escape and remove the valve's rim retaining nut if fitted. Leave the valve core installed.

Push the tyre edges into the rim's centre channel. Starting away from the valve, use a plastic tyre lever to lift one bead over the rim edge. Work around until that side is free, leaving the other bead on the rim. Do not use screwdrivers.

Pull out the tube, withdrawing the valve carefully. Note its position relative to the tyre. Gently inflate it just enough to give it shape. Listen and feel for escaping air, or submerge sections in water and look for a repeated stream of bubbles. Mark the hole and check for additional leaks.

Inspect the matching part of the tyre, then its entire inside and tread. Use good light and a cloth rather than sliding bare fingers over possible glass or thorns. Carefully remove embedded debris. Check that rim tape covers the spoke holes and is undamaged. Replace damaged parts. Replace tubes with valve-base damage or tears unsuitable for patching.

Deflate the tube and dry it completely. Lightly roughen an area larger than your patch with the kit's abrasive. Brush off dust without contaminating the surface. Follow your patch kit's preparation instructions.

Spread a thin, even layer of the kit's vulcanising fluid over the prepared area. Let it dry for the time specified by the kit before applying the patch. Work with ventilation and away from flames. Self-adhesive patches use a different procedure and do not need this fluid.

Remove the patch backing without touching the bonding surface. Centre the patch over the hole and press firmly across its whole surface and edges for the time specified by the kit. Follow the kit's instructions for any top film and required waiting time.

After the required waiting time, gently inflate the tube just enough to give it shape. Check the patch and the rest of the tube for escaping air. Use water if needed, then dry the tube. If it leaks or the patch lifts, repair it correctly or fit a compatible replacement tube.

Leave only enough air in the tube to give it shape. Check the tyre's direction arrow if the tyre was fully removed. Insert the valve straight through the rim hole and tuck the tube evenly into the tyre without twisting it. Leave any valve retaining nut loose.

Starting opposite the valve, work the loose bead onto the rim with your thumbs, keeping seated sections in the centre channel. Finish near the valve, pushing the valve gently inward to free the tube from beneath the bead. Avoid levers where possible. Inspect both sides all the way around for trapped tube.

Add a little air and check that the tyre's seating line is even around both sides of the rim. If it bulges or sits unevenly, deflate and correct it. Inflate to a pressure appropriate for your tyre, rim and load, within the applicable manufacturer limits. Close the Presta tip if present, finger-tighten any retaining nut and replace the cap.

Fully seat the wheel and secure the axle exactly as the manufacturer specifies, using the specified torque where applicable. Reconnect any opened rim brake. Spin the wheel to check alignment and test both brakes while stationary. Confirm the tyre holds pressure. Take a short, slow test ride in a safe place and recheck before riding normally. If the rim brake needs further adjustment, see how to adjust bicycle rim brakes before riding.