First: figure out what kind of flat you have
A slow leak that hisses and starts sealing on its own is a tubeless win — spin the wheel and let the sealant close it. A sudden pop or a tire that's totally flat in seconds is a bigger hole, a sidewall cut, or a bead that unseated. Different problems, different fixes.
Fix a tubeless flat with a plug
- Find the hole. Rotate the tire slowly and look for wet sealant or a hissing spot.
- Use the reamer from your plug kit to open the hole slightly, then push a plug through with the insertion tool. Trim the excess flush.
- Re-inflate with CO2 or a pump. Spin the tire to let sealant finish the job.
- Ride slow for the next minute to confirm the seal holds.
When to give up and install a tube
If the tire won't hold air after a plug, if the sidewall is cut, or if the bead is completely unseated and you can't reseat it with a mini pump, install a tube. Remove the tubeless valve first, pull one side of the tire off with levers, install the tube (partly inflated so it doesn't pinch), then work the tire back on by hand — levers as a last resort so you don't pinch the tube.
What to always carry
- A plug kit (Dynaplug, Stan's Dart, or generic bacon strips).
- A spare tube sized for your tire.
- Two tire levers.
- A mini pump AND at least one CO2 cartridge with a head.
- A multitool with a chain breaker.
How to make flats less likely in the first place
Run the right tire pressure — most beginner women on 40mm tubeless tires do great in the 28–35 psi range. Fresh sealant (top up every 3–4 months) closes small holes before you notice them. And avoid the temptation to run sub-30mm tires on rough gravel.