AI quick summary
- Carry a spare tube, tyre levers, a pump or CO2, and know how your wheel comes off (thru-axle vs quick release).
- Find the cause before reinstalling — glass or wire still in the tyre will flat the new tube instantly.
- For tubeless, a small puncture often seals with sealant; a big cut needs a plug or a tube.
/ 01
What to carry
A spare tube (correct valve type and tyre size), two or three tyre levers, a mini-pump or CO2 inflator, a patch kit as backup, and a multi-tool for removing the wheel. That kit lives in your saddle bag or jersey pocket on every ride — a flat without it means a long walk.
/ 02
Remove the wheel
Shift to the smallest rear cog (and middle ring up front) to give the chain slack and clear the derailleur. Open the rim brake or release the caliper. For a quick release, flip the lever open; for a thru-axle, unscrew and pull it out. Drop the wheel out carefully.
/ 03
Get the tube out and find the cause
Hook a tyre lever under one bead and lever it over the rim, then slide it around to free one side. Pull out the tube, keeping track of which way it sat relative to the tyre. Before you do anything else, find what caused the flat: run a finger around the inside of the tyre and check the rim tape for a sharp edge. A thorn or wire left in the tyre will puncture your new tube the moment you inflate it.
/ 04
Install the new tube
Add a little air to the new tube so it holds its shape, then seat it inside the tyre starting at the valve. Tuck both beads back into the rim by hand, working away from the valve and finishing at the valve. Avoid using levers to reseat the last section — that's how you pinch and puncture the new tube. Check the bead is seated evenly all the way around, then inflate fully.
/ 05
Tubeless flats
On a tubeless setup, a small puncture often seals itself as the sealant does its work — you may only need to add air. A bigger hole that won't seal can be plugged with a tyre plug (a 'bacon strip'). A cut too large to plug means installing a tube: remove the tubeless valve core, treat the tyre like a normal clincher, and ride home carefully.
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