Fix your own bicycle

Cue 1 The M traced over a bicycle, one stroke at a time.

AMARA 00:00 I have owned bikes for twenty years and I have never once done a systematic check. I just get on and ride.

NADIA 00:08 Most people do, and most of the time it is fine, because a bicycle is a very forgiving machine right up until the moment it is not. The M check takes five minutes and it exists because the failures that hurt people are boringly predictable.

AMARA 00:26 Why an M?

Cue 2 Wheel spinning with the pad gap opening and closing to show a buckle.

NADIA 00:28 Because your hands trace one. Front wheel, up to the bars, down to the pedals, up to the saddle, down to the back wheel. It is a route, not a checklist, which is why it survives contact with a cold morning when you are in a hurry.

AMARA 00:46 Start me at the front wheel. What am I actually doing?

NADIA 00:51 Spin it and watch the gap at the brake pads. If that gap opens and closes as it goes round, the wheel is buckled. Then grab the tyre at the top and rock it towards you and away. If it knocks, the hub bearings are loose.

Cue 3 Hands rocking a tyre side to side at the top of the wheel.

AMARA 01:09 And the quick release?

NADIA 01:11 Check it is properly closed, not spun up finger tight. The lever should need a firm push with the heel of your hand and leave a mark on your palm. A quick release that is merely tight will work loose, and a front wheel leaving a fork at speed is one of the worst things that can happen on a bicycle.

AMARA 01:35 Tyres?

Cue 4 Quick release lever closing, with the palm mark it should leave.

NADIA 01:36 Look for cuts, embedded flint, and bulges. A bulge in the sidewall means the casing has failed and the only thing holding the pressure is rubber. That is not a wait and see, that is a replace before you ride.

AMARA 01:52 Up to the bars.

NADIA 01:53 Stand over the front wheel, grip it between your knees, and try to turn the bars. Nothing should move. If the bars turn against the wheel, the stem bolts are loose and you have no steering when you most need it.

Cue 5 Knees gripping the front wheel while the bars refuse to turn.

AMARA 02:10 Then down to the pedals.

NADIA 02:12 Rock the crank arms towards and away from the frame. Any knock is a loose crank bolt or bottom bracket. And a loose crank matters more than people think, because riding on one for a week will chew out the crank arm and turn a two minute job into a new chainset.

AMARA 02:32 So what actually stops me riding today?

Cue 6 Four stop signs for the four faults that end the ride.

NADIA 02:35 Four things. Brakes that will not lock the wheel or a lever that pulls to the bar. A wheel that is not properly secured, or a bulging or split tyre. Bars or stem that move relative to the wheel. And any crack in a frame, fork or handlebar.

AMARA 02:54 Cracks are the one I would be tempted to ignore.

NADIA 02:58 Do not. Aluminium and carbon do not bend and complain the way steel does. They hold, and then they let go all at once. A cracked fork is not a judgement call and it is not a home repair.

AMARA 03:14 Last thing. How do I know when a job is beyond me?

NADIA 03:19 There is a proper list, and it is in the written material. But the test that has never let me down is simpler than a list. Would you be happy watching somebody you love ride that bike down a long hill? If you find yourself starting a sentence with it is probably fine, you already know the answer.

Cue 1 Lever pulled to the bar, then the same lever firm after a barrel adjustment.

AMARA 03:42 My brake lever comes almost to the handlebar before anything happens. Do I need new pads?

NADIA 03:48 Probably not, and this is the commonest wasted twenty pounds in cycling. A lever coming to the bar is usually cable slack. Look at the pads first: if they still have grooves in them, they are fine and the cable is the problem.

AMARA 04:06 So how do I take up the slack?

Cue 2 Pad height animation: too high cutting the tyre, too low diving under the rim, correct square on.

NADIA 04:09 The barrel adjuster, which is the little knurled barrel where the cable enters the lever or the caliper. Turn it anticlockwise, so it unscrews outwards, and it pulls the cable tighter and brings the pads in. A quarter turn at a time, checking as you go.

AMARA 04:27 And if I run out of adjustment?

NADIA 04:30 Then wind the barrel all the way back in, undo the pinch bolt at the caliper, pull a few millimetres of cable through with pliers, hold it, and do the bolt back up. Now you have the whole range of the barrel adjuster back for fine tuning later.

Cue 3 Card behind the pad to set toe in, then removed.

AMARA 04:49 Let us talk about the pads themselves. What am I setting?

NADIA 04:54 Four things, and in this order. Height, alignment, toe in, tension.

AMARA 04:58 Height first.

Cue 4 Worn pad with grooves gone beside a new one.

NADIA 04:59 The pad sits fully on the braking surface of the rim, square, with a small gap below the tyre. And this is the one that hurts people. A pad set even slightly too high will rub the tyre sidewall, and it will cut through it. Not might. Will.

AMARA 05:18 What about too low?

NADIA 05:20 Worse in a different way. A pad that sits below the rim can dive underneath it under hard braking and jam the wheel. Square on the braking surface, every time.

Cue 5 Fingernail running across a concave rim braking surface.

AMARA 05:32 Toe in. I have heard mechanics say this and never understood it.

NADIA 05:36 Set the front of the pad to touch the rim a fraction before the back. About the thickness of a coin. That is it. It stops the pad chattering against the rim, which is where brake squeal comes from. A folded piece of card held behind the back of the pad while you tighten it will set it for you.

AMARA 06:00 Now the thing I would never think to check.

Cue 6 Disc brake with a spacer fitted where the wheel would be.

NADIA 06:04 The rim. Everybody checks pads and nobody checks rims. Every time you brake you are sanding the rim away, and most rims have a wear indicator, a groove or a dimple in the braking surface.

AMARA 06:18 And when it wears through?

NADIA 06:20 The sidewall goes concave, and eventually it splits under tyre pressure and the tyre comes off the wheel. Run a fingernail across the braking surface. If it dips into a hollow, get it looked at before you ride it again.

AMARA 06:36 Anything I should never do?

NADIA 06:38 Never let oil, chain lube or degreaser near a pad or a braking surface. And on hydraulic disc brakes, never pull the lever with the wheel out, because the pistons close up and you will be resetting them with a tyre lever and a lot of swearing. Put the plastic spacer in. That is what it is for.

Cue 1 Fingers tracing the inside of a tyre with a flint revealed.

AMARA 07:01 I can change a tube. I still get a puncture again a mile later about half the time.

NADIA 07:08 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 07:19 The flint is still in there.

Cue 2 Tube laid against the wheel to map the hole to the tyre position.

NADIA 07:22 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 07:39 Is there a trick to knowing where to look?

NADIA 07:42 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.

Cue 3 Snakebite: two holes side by side, with the rim pinch shown in cross section.

AMARA 08:02 What does the hole itself tell me?

NADIA 08:05 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 08:21 What causes those?

Cue 4 Bead being pushed into the rim well to create slack.

NADIA 08:22 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 08:38 Anything else?

NADIA 08:39 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.

Cue 5 Tyre inflated to a third with the bead line even, then uneven and rejected.

AMARA 08:53 Right. Fitting. What goes wrong?

NADIA 08:55 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 09:04 How?

Cue 6 Pressure scale with rider weight and tyre width shifting the recommendation.

NADIA 09:05 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 09:22 Everybody reaches for a tyre lever at the last bit.

NADIA 09:26 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 09:45 Before I inflate?

NADIA 09:46 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 10:15 Last question. Pressure. I have always just pumped to the maximum on the sidewall.

NADIA 10:20 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.