Skill guide · Transportation

Basic Bicycle Maintenance & Repair

The Transportation chapter's Tier 2 names a bicycle as a genuinely practical fuel-free backup, but only if it stays rideable. Unlike a car, a bike is DIY-friendly enough that almost anyone can learn the handful of repairs that keep it running: fixing a flat, keeping the chain lubricated, and knowing when a shifting problem is dirt, not damage.

Fixing a flat: patch it or replace the tube

Check for a tubeless setup before assuming there's a tube to pull out

Many gravel and mountain bikes, and a growing number of road bikes, run tubeless: no inner tube at all, just liquid sealant inside the tire that self-seals small holes on its own. A tire that sloshes when you shake the wheel, or has a small brass valve-core nut visible at the base of the valve, is tubeless. A puncture under about 2mm often seals itself once the wheel spins and works sealant into the hole; a slightly larger one can usually be closed with a tubeless plug kit (a rubberized cord forced into the hole from outside, no tire removal needed). If neither works, or the cut is too large to trust, unscrew the valve core's lock ring and install a standard inner tube exactly as described below, a tubeless tire still holds a tube fine as a get-home fix.
  1. Flip the bike upside down (or use a stand). For a rim-brake bike, open the brake caliper's own quick-release first so the tire can clear the pads. Check which of two axle systems your bike uses first, since they come apart differently: a quick-release skewer has a lever, pull it straight outward, away from the wheel, until it swings a full 180 degrees into the open position, most levers are stamped "Open"/"Close" to confirm you're reading it right, then only loosen the adjusting nut on the far side if the wheel still won't clear the dropouts. A thru-axle, the standard on most disc-brake road, gravel, and mountain bikes made in the last several years, has no lever at all: it threads directly into the frame or fork and has to be unscrewed with a hex key (usually 5mm or 6mm) or its own fold-out lever handle, then pulled all the way out before the wheel drops free. For a rear wheel specifically, shift to the smallest rear cog first, then pull the derailleur body backward to slacken the chain before lifting the wheel out, guiding it down past the chain and derailleur cage as it comes free. If the rear derailleur has a clutch (common on gravel and mountain bikes with a 1x drivetrain), switch it to its off/unlocked position before forcing the wheel out, Shimano models have a small clutch lever, SRAM models need the cage pushed forward and locked, since fighting an engaged clutch to remove the wheel can damage the mechanism.
  2. Work a tire lever under the tire's edge, hook the other end on a spoke to hold it up, then work a second lever around the rim until one whole side of the tire is off.
  3. Pull the tube out and find the leak: re-inflate it slightly and listen or feel for escaping air, or submerge sections in water and watch for bubbles.
  4. Check the inside of the tire itself for whatever caused the puncture (a thorn, a sliver of glass or wire) before putting a new or patched tube back in; skip this and the same object punctures the next tube too.
  5. Work the tube into the tire and the bead back onto the rim mostly by hand; only use a lever as a last resort, and never a screwdriver or knife, which can puncture the tube you just installed. Inflate to low pressure first and check both sides of the tire for a visible, even line just above the rim (the bead seated correctly) before inflating the rest of the way; an uneven line usually means the tube is pinched under the bead somewhere.

Two different kinds of stick-on patches exist, and using the wrong procedure for the one you have is a real way to fail a repair. A glueless patch works as written: lightly scuff the area around the hole so the adhesive bonds, peel the backing, then press the patch on firmly and hold it for a minute. A traditional rubber-cement patch kit works differently: scuff the area the same way, apply a thin, even layer of the cement from the kit, then wait for it to dry until tacky, not press the patch onto wet cement, before applying the patch. Treat a patch as a get-you-home fix rather than a permanent one, though a properly applied patch can last a long time in practice. Replacing the tube outright is faster and more reliable when time matters, which is why carrying at least one correctly-sized spare tube is worth more than carrying only patches. Match the new tube's diameter and width numbers to what's printed on the tire's sidewall before buying spares.

Before you can add air at all, know which of the two incompatible valve types your bike uses: a narrow, threaded Presta valve needs the small knurled nut at its tip unscrewed (counterclockwise) before a pump will move air, then closed again after; a wider Schrader valve, the same type used on car tires, just needs the cap off. Check which one your bike uses before buying a pump or inflator, some pump heads only fit one type. Inflate to the PSI (or BAR) range printed on the tire's own sidewall, not a single fixed number: road tires typically run 100-140 psi, hybrid/urban tires 60-80 psi, and mountain bike tires 30-50 psi, with heavier riders running toward the top of the range and the rear tire commonly a few psi higher than the front.

Chain care: the maintenance that prevents most other problems

Clean and re-lubricate the chain roughly every 100 to 150 miles of riding, after any wet or muddy ride regardless of mileage, or as soon as it starts sounding gritty or dry, whichever comes first. Wipe the chain down with a rag and a degreaser to pull off built-up grime, let it dry, then apply lubricant drop by drop so it reaches each link, and wipe away the excess. Excess lube left on the outside of the chain doesn't help it run smoother; it just collects more dirt, which is the opposite of the goal.

Shifting problems: usually dirt, not damage

Most shifting complaints come from a dirty drivetrain, a stretched or gunked-up cable, or a derailleur knocked slightly out of adjustment, not a broken part. Brush caked grease and grit off the derailleur's small jockey wheels and give the derailleur's pivot points a light touch of lubricant, without over-oiling them the same way the chain shouldn't be over-oiled. Clean the whole drivetrain (chain, cassette, chainrings) before assuming a shifting issue needs a real mechanical fix; a surprising share of "broken derailleur" complaints resolve with nothing more than a proper cleaning.

Riding while hauling cargo

A loaded bike, whether carrying panniers, a trailer, or a bag of supplies, handles differently than an empty one: it's slower to turn, needs more distance to stop, and is less stable at low speed, especially over the first few rides while getting used to the new balance. Practice riding loaded on a familiar, low-traffic route before relying on it for a real trip, the same reasoning this manual applies to breaking in evacuation footwear or testing a rucksack under real weight.

Quick Reference

TaskInterval / triggerNote
Chain lubeEvery 100–150 miles, or after wet ridesWipe excess off; too much lube attracts dirt
Chain/drivetrain cleaningEvery 2–3 lube cyclesDegreaser + rag; resolves most shifting complaints
Tire checkBefore every real-use rideCheck for embedded debris after any flat
Spare tube fit checkBefore storing as emergency backupMatch diameter/width printed on the tire sidewall

A basic repair kit:

ItemPurposeNote
Tire levers (2-3) Removing the tire from the rim Plastic is fine; keep a spare, they do snap
Patch kit Emergency/get-home fix Check the glue hasn't dried out before relying on it
Spare tube(s) Fast, reliable fix Correct size for your specific tire
Mini pump or CO2 inflator Re-inflating after a repair A pump never runs out; CO2 is faster but finite
Chain lube + rag Routine maintenance A dedicated bike lube, not household oil
Multi-tool Minor adjustments on the road Covers 4mm, 5mm, and 6mm hex/Allen, the sizes used on most stem, seatpost, and brake/derailleur mounting bolts, plus a Phillips or flat screwdriver bit

Tip

Dust a stored spare tube with talcum powder before it goes in the kit

A bare rubber tube left folded up for months tends to stick to itself, which makes it harder to unfold and seat correctly when you actually need it. A light dusting of talcum or baby powder inside a sealed ziplock bag keeps the rubber from bonding to itself and doubles as a light lubricant that makes the tube easier to work into the tire during the actual repair.

Sources