Punctures: fix it properly, and stop it happening again

Amara I can change a tube. I still get a puncture again a mile later about half the time.

Nadia Then you are skipping the only step that matters, and so does nearly everybody. You are fixing the hole and leaving the cause sitting in the tyre.

Amara The flint is still in there.

Nadia The flint, the thorn, the tiny shard of glass. Before you fit anything, run your fingers all the way round the inside of the tyre. Carefully, because if there is something sharp in there you are about to find it with your fingertip.

Amara Is there a trick to knowing where to look?

Nadia Yes, and it is the thing that separates people who fix punctures from people who replace tubes. Line the tube up with the valve hole in the rim, find the puncture, and then look at exactly that spot in the tyre. You have just told yourself where the cause is.

Amara What does the hole itself tell me?

Nadia Quite a lot. One small hole on the outer face is a sharp object. Two little holes side by side on the inner face is a snakebite, a pinch flat, and that one is not about sharp objects at all.

Amara What causes those?

Nadia Low pressure and a hard edge. The tyre bottoms out, the tube gets pinched between the rim and whatever you hit. So the fix is not a better tyre, it is more air, or riding lighter over the edges.

Amara Anything else?

Nadia A hole on the rim side, or around the valve, often means rim tape that has slipped and exposed a spoke hole. Worth a look, because a new tube will do exactly the same thing.

Amara Right. Fitting. What goes wrong?

Nadia Pinching the new tube under the bead. It is the reason a repair fails within thirty seconds of inflating and it is entirely avoidable.

Amara How?

Nadia Put just enough air in the tube to give it shape. Not firm, just shaped. Fit the valve first, push the stem up into the tyre so it seats, then work the bead on with your thumbs away from the valve in both directions.

Amara Everybody reaches for a tyre lever at the last bit.

Nadia And the last bit is exactly where levers pinch tubes. Try thumbs first. There is a knack: push the already fitted bead down into the well in the centre of the rim, and suddenly you have enough slack to get the last section on by hand.

Amara Before I inflate?

Nadia Push the tyre sideways all the way round on both sides and check no tube is peeking out. Then inflate to about a third, and look at the bead line, the little moulded line just above the rim. It should be evenly visible all the way round, both sides. If it wanders, the tyre is not seated. Let it down and start again, because an unseated tyre can blow off the rim.

Amara Last question. Pressure. I have always just pumped to the maximum on the sidewall.

Nadia That number is a range, not an instruction, and riding at the maximum is usually slower, harsher, and more puncture prone on real roads, not less. Heavier rider, more air. Wider tyre, less. Rough or wet, less. Then adjust by feel: pinch flats mean go up, harsh and skittery means come down.