Three bike fixes, and the mistake that ruins each one

Quick answer: Most second flats happen because whatever caused the first one is still stuck in the tire. Find it before the new tube goes in. And never, ever put oil on a squeaky brake.

You're three miles from home when the back tire starts to feel squishy. A minute later you're riding on the rim. Most guys call for a ride. Some walk. The ones with two tire levers and a spare tube under the seat are rolling again in fifteen minutes.

Each of these three repairs has one mistake baked into it, the thing nearly everybody does the first time. Skip that mistake and you'll be better at this than half the adults on your street.

What lives under your seat

Get a small saddle bag and put these in it:

• Two plastic tire levers. Not a screwdriver. A screwdriver will chew up your rim and stab your new tube.
• One spare tube in the right size. The size is printed on the side of your tire, something like 26 x 2.1 or 700 x 28c. Match it exactly.
• A patch kit for the day you get two flats.
• A mini pump that fits your valve type. Car-style valves are Schrader. The skinny ones with a tiny nut on top are Presta. Check yours before you buy.

If your wheels bolt on instead of using a quick-release lever, add a wrench that fits the axle nuts. On a lot of bikes that's 15mm. Try it at home first.

Fixing a flat

Get the wheel off. If it's the back wheel, shift to the smallest gear in the back so the chain has slack. If you have rim brakes, open the little release on the brake so the tire can slip past the pads. Then open the quick release or loosen the nuts and drop the wheel out.

Get the tire off. Let out any air that's left. Hook one tire lever under the edge of the tire, across from the valve, and pull it over the rim. Clip that lever to a spoke. Slide the second lever in a few inches away and run it around the rim. One side of the tire pops off. Pull the tube out.

Now the part everybody skips. Pump a little air into the old tube and find the hole. Listen for it, or hold the tube near your cheek and feel for the air. Then lay the tube next to the tire, with the valve lined up where it sits in the rim. The hole in the tube tells you exactly where on the tire to look.

Go slow here. Run a rag or a cotton ball around the inside of the tire. It'll snag on what your eyes miss. Use your fingers carefully, because the culprit is usually a sliver of glass, a thorn or a tiny piece of wire, and it's sharp. Pull it out.

If you skip this, you'll put in a brand-new tube, pump it up, ride a mile and go flat again in the same spot. Now you're out of spare tubes and walking anyway.

Two other things to check while you're in there:

• Two small slits side by side mean a pinch flat. That's not a thorn. Your tire was too soft and you hit a curb or a pothole hard enough to pinch the tube against the rim. The fix is keeping your tires pumped up.
• A hole on the inside of the tube, facing the rim, means the rim strip has slipped and a spoke hole is cutting into it. Slide the strip back so it covers every hole.

Put it back together. Put just enough air in the new tube that it holds a round shape. Push the valve through the rim first, then tuck the tube inside the tire all the way around. Push the tire edge back onto the rim with your thumbs, starting at the valve and working both directions. The last bit, opposite the valve, is the hardest. Use your thumbs, not a lever, if you can. Levers love to pinch new tubes.

Before you pump it up, look all the way around both sides. If you see any tube peeking out under the tire edge, push it back in. Pump to the pressure printed on the tire's sidewall. It'll give a range in PSI. Close the brake release. People forget that one constantly and then wonder why they can't stop.

A chain that fell off

This one's the fastest fix of the three, and the mistake is forcing it.

When a chain drops, it's usually come off the front gears, the ones by your pedals. The instinct is to grab it and yank, or crank the pedals hard and hope. Don't. You can bend the chain or twist the derailleur, the arm that moves the chain between gears in the back. Then a two-minute problem costs real money.

If your bike has gears:

1. Shift to the smallest gear in front and the smallest in back.
2. Push the back derailleur forward, toward the front of the bike. That gives the chain slack.
3. Lay the chain over the bottom teeth of the front gear.
4. Lift the back wheel and turn the pedals slowly forward. The chain walks itself back on.

Grab a leaf or a rag before you touch the chain. That black grease doesn't come out of white shoes.

If it's a single-speed or BMX, a dropped chain usually means it's loose. Loosen the back axle nuts, pull the wheel back until the chain has about a half inch of up-and-down play, keep the wheel straight in the frame, and tighten the nuts hard.

If the chain keeps falling off on a geared bike, something needs adjusting, or the derailleur got bent when the bike tipped over. That's a bike shop job unless someone who knows the work is showing you.

While you're down there, lube the chain. Real chain lube, one drop on each link while you backpedal, then wipe off the extra with a rag. WD-40 isn't chain lube. It's mostly a cleaner, and it'll strip off what's there.

Brakes that scream

Squeaky brakes are annoying. Oily brakes are dangerous. The single worst thing you can do is spray lube at a squeak. It might go quiet, and that's because your brakes barely work anymore.

Squealing usually comes from dirt, worn pads, or pads hitting the rim at a bad angle.

For rim brakes, the pads grab the metal edge of the wheel:

• Wipe the braking edge of the rim with rubbing alcohol on a clean rag.
• Look at the pads. If they're shiny and hard, rough them up lightly with sandpaper. Pick out any little bits of metal stuck in them.
• If the grooves in the pads are worn away, replace them. Pads are cheap.
• Check the angle. The front of each pad should touch the rim a hair before the back does. Mechanics call this toe-in. Loosen the pad bolt, tuck a folded piece of thin cardboard between the back of the pad and the rim, squeeze the brake and tighten the bolt.

For disc brakes, the pads grab a metal disc by the hub. Don't touch that disc with your fingers. The oil from your skin is enough to start a squeal. Clean it with rubbing alcohol and a clean rag. If the pads soaked up oil, cleaning won't save them. They need replacing.

Last check: squeeze both brake levers hard. If either one comes all the way back to the handlebar, don't ride it. Show it to someone who knows brakes.

When to hand it off

Some things aren't a driveway fix. A wheel that wobbles side to side. A crack anywhere in the frame. Brakes that still feel weak after you've done everything above. Take those to a bike shop, or get a parent to look at it with you. Knowing where your skill stops is part of having the skill.

The part that isn't about bikes

Once you can do this, people will notice. Your little sister's bike has been sitting with a flat since spring. Your buddy's chain falls off every ride. Fix them. You'll learn more on their bikes than on yours, and fixing things for the people you live with is how reliability gets built in the house you already live in.

If you ever borrow a bike, give it back better than you got it. Tires pumped. Chain lubed. Mud hosed off. Nobody asks for that, and that's exactly why it gets remembered. Reliable men are built at fifteen, one small fix nobody told you to do.

Next time somebody's standing at the side of the road with a flat, you won't be calling for a ride. You'll be the one they call.