Patch or Replace a Tube

Whenever it happens. It happens more often on worn tires, on underinflated tires, and after riding through glass or a gravel shoulder. If you are getting flats regularly, the answer is almost never better tubes; it is tire condition, pressure, or something still embedded in the casing.

The interval on this page is Event-triggered. Not on the calendar — done when something happens.

• A spare tube in the right size with the right valve
• Two or three tire levers
• A patch kit
• A pump or an inflator, and a pressure gauge

1. Get the wheel out without losing anything

   Release the brake if it is a rim brake, open the quick release or thru axle, and lift the wheel clear. On a rear wheel, shift to the smallest sprocket first so the derailleur is out of the way, and pull the derailleur back as the wheel comes down. Put the axle hardware somewhere it cannot roll into a drain.

2. Get the tire off one side only

   Let out any remaining air, push the tire beads toward the center of the rim to create slack, then hook one tire lever under the bead and clip it to a spoke. Work a second lever around from there. You only need one side of the tire off to get the tube out, and leaving the other side seated saves a lot of work.

3. Find the hole before you do anything else

   Pull the tube out, inflate it a little, and listen and feel for escaping air. A pair of holes side by side is a pinch flat and means the tire was too soft. A single small hole on the outer face is something sharp. A hole on the rim side points at the rim tape or a spoke end.

4. Find what caused it, in the tire

   Line the tube up with the tire so you know which part of the casing the hole corresponds to, then run a finger carefully around the inside of the tire at that point, and then around the whole casing. Glass and wire are easy to miss and are still there waiting. Check the rim tape covers every spoke hole while the tire is off.

5. Patch it or replace it, deliberately

   Carry a spare tube for the roadside; swapping is faster and more reliable when it is cold and getting dark. Patch at home, where a glued patch has time to cure properly: rough the area, apply a thin layer of cement, wait until it is tacky rather than wet, then press the patch down hard from the center out. A tube with a hole at the valve base or a long split is not patchable.

6. Put it back without pinching it

   Put just enough air in the tube to give it shape, seat the valve straight through the rim, and tuck the tube into the tire all the way around. Work the bead back on with your thumbs, finishing at the valve. Use levers as a last resort, because a lever is the most common way a brand new tube gets pinched.

7. Check the bead, then inflate in stages

   Before full pressure, inflate a little and look all the way around both sides: the molding line on the tire should sit an even distance from the rim, with no tube showing anywhere. Push the tire aside at a few points to confirm the tube is not trapped under the bead. Then inflate to the pressure you want, within the range printed on the sidewall.

• Fitting the new tube without finding the cause, which produces a second flat within a mile and a much worse mood.
• Levering the last section of bead on with a tire lever, which pinches the tube against the rim and punctures it before the wheel is even back in the bike.
• Rushing a glued patch by pressing it on while the cement is still wet, when the cement needs to go tacky first to bond at all.

• Inner Tubes
• Pumps and Portable Inflators

• Check Tire Pressure
• Inspect Tires for Wear and Cuts
• The ABC Check Before Every Ride

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