A new tube will not stay inflated if the cause of the flat is still in the tire or at the rim. John Waller demonstrates the same careful sequence used in the shop: find the cause, protect the new tube, seat the tire correctly and check the wheel before riding.
Replacing a tube is straightforward when you work methodically. The most important part is not simply installing a new tube—it is finding and correcting whatever caused the old one to lose air.
What you will need
- A replacement tube matching the tire size and valve type
- A bicycle pump with a pressure gauge
- Plastic tire levers if the bead cannot be removed by hand
- The correct wrench or hex key if the wheel does not use a quick release or thru-axle lever
Tube replacement from wheel removal to final check
Remove the tube and find the cause
Remove the wheel, fully deflate the tube and take one tire bead off the rim. Pull the valve out of the rim and remove the tube.
Locate the puncture if possible. Carefully inspect the inside and outside of the tire for glass, wire, thorns or a protruding object. Check the rim tape for gaps, sharp edges or exposed spoke holes. Remove the cause before installing the replacement.
Give the new tube a little shape
Add only enough air for the tube to hold its round shape. This makes it easier to place and helps prevent folds and twists.
Insert the valve squarely through the rim, then work the tube evenly into the tire. Make sure it is not twisted and that no portion is hanging outside the tire bead.
Seat the tire bead without pinching the tube
Starting opposite the valve, press the loose tire bead into the rim and work toward the valve from both directions. Keep the already-installed bead down in the rim’s center channel to create slack.
Finish near the valve. Push the valve slightly into the tire so the tube is not trapped beneath the bead, then pull it back into position. Avoid using a tire lever to install the final section unless necessary; a lever can pinch the new tube.
Inflate gradually and inspect both sides
Add a small amount of air, then inspect the entire circumference on both sides. The molded line near the tire bead should remain an even distance from the rim.
If the bead is uneven or the tube is visible, release the air and correct it. Once the tire is seated properly, inflate to an appropriate pressure within the limits marked on the tire and rim.
Reinstall the wheel and check your work
Seat the wheel fully and secure the axle using the bicycle manufacturer’s procedure. Reconnect or close the brake if it was released for wheel removal.
Spin the wheel and confirm that it turns freely, remains centered and does not rub. Squeeze the brake lever to verify normal braking before riding. Never ride with a loose axle, uneven tire bead or disconnected brake.
When a new tube is not the complete repair
Get help when you find:
- A cut or bulge in the tire casing
- A cracked, dented or badly out-of-true rim
- Damaged or displaced rim tape
- A valve hole with a sharp edge
- Repeated flats without an obvious cause
- An axle or brake you cannot secure confidently
JW Bicycle Repair provides tube replacement, puncture diagnosis, tire installation and tubeless service in Augusta. Bringing the whole bicycle allows the wheel installation and brake operation to be checked before it leaves the shop.
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