How to Fix a Flat Bike Tyre, Step by Step
A flat tyre is the one roadside problem every cyclist meets, and fixing it is a ten-minute skill that means a puncture never ends your ride. Here is how to do it, step by step, and what to carry.
- Carry three things on every ride: a spare tube (the right size), two tyre levers, and a mini-pump or CO2 inflator. With those, a flat is a quick fix.
- Swapping the tube is faster and more reliable roadside than patching. Patch the old tube later at home as a spare.
- Always find WHAT caused the flat (a thorn, glass, a sharp bit) before fitting the new tube, or it will puncture again immediately.
- Note your valve type: Presta (thin, with a lock nut) or Schrader (fat, car-style). The tube and pump must match.
- Practise once at home before you need it on the road. The first flat is slow; the fifth takes five minutes.
Get the wheel and tyre off
Shift the chain to the smallest rear cog (makes the back wheel easier), open the brake if it is a rim brake, and undo the quick-release or thru-axle to drop the wheel out. Let out any remaining air. Then unseat one side of the tyre: push the tyre bead toward the centre of the rim to loosen it, hook a tyre lever under the bead and clip it to a spoke, use a second lever a few inches along, and run it around to free one whole side of the tyre. Pull the old tube out, leaving the tyre partly on the rim. You do not usually need to fully remove the tyre.
Find the cause, then fit the new tube
This step is the one beginners skip and regret. Run your fingers carefully around the inside of the tyre (watch for sharp bits) and inspect the outside for whatever caused the puncture, a thorn, a shard of glass, a wire. If it is still embedded and you fit a fresh tube, you will flat again in minutes. Remove it. Then put a little air in the new tube so it holds its shape, tuck the valve through the rim hole, and feed the tube up inside the tyre all the way around. Work the tyre bead back onto the rim with your thumbs, finishing at the valve; avoid tyre levers here if you can, as they can pinch the new tube.
Inflate, check, and roll
Before full inflation, push the valve up and the tyre in around the valve to make sure the tube is not pinched under the bead, then check all the way around that no tube is peeking out. Inflate slowly to a low pressure and check the tyre is seating evenly (the moulded line sits just above the rim all the way round), then pump to your riding pressure, which is printed on the tyre sidewall. Refit the wheel, close the brake and quick-release properly (this matters for safety), give the wheel a spin, and you are rolling. Take the old tube home; you can patch it as your next spare.
Learn your valve type and pressure. Presta valves (thin, with a little lock nut you unscrew) need a Presta-compatible pump head; Schrader (fat, like a car tyre) is the other. Your correct tyre pressure range is printed on the tyre sidewall, use it.
Common questions
What do I need to fix a flat on a ride?
Should I patch the tube or replace it?
Why did my new tube go flat again immediately?
How do I avoid pinching the new tube?
What pressure should I pump my tyres to?
Gear guides for Cycling
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