Keeping a bike running well.

The pre-ride M-check

The M-check is the standard way to look over a bike. You trace an M shape from the front wheel up to the bars, down to the bottom bracket, up to the saddle, and down to the rear wheel — so nothing gets missed. It takes a minute or two.

• Front wheel & tyre: spin it — is it true and does it run without rubbing? Check the tyre for cuts and correct pressure, and that the wheel is done up (quick-release closed, or thru-axle torqued).
• Front brake & headset: squeeze the lever — firm, not to the bar. Rock the bike forward with the brake on; a knock usually means a loose headset.
• Bars, stem & forks: grip the front wheel between your knees and try to twist the bars — the stem shouldn't move. Look over the fork for cracks or damage.
• Bottom bracket & chainset: grab a crank arm and push side-to-side — no play. Check the chain and chainring for wear and that pedals are tight.
• Saddle & seatpost: the saddle shouldn't twist or slip; the post should be above its minimum-insertion line.
• Rear wheel, brake & gears: as the front, plus check the rear brake and that gears shift cleanly up and down.

The ABC quick check

When you don't have time for the full M-check, the ABC covers the three things most likely to leave you stranded or hurt:

• A — Air: tyres pumped to the right pressure and holding it.
• B — Brakes: both levers firm and stopping the wheels.
• C — Chain & cranks: chain clean and lubed, cranks tight with no wobble. (Some also add Quick-releases — check wheels and seatpost are done up.)

Tyre pressure

Tyre pressure is the single change that most affects how a bike rides — and the most neglected. Too high and the ride is harsh and grip is poor; too low and you risk pinch flats and sluggish handling. Tyres lose air slowly on their own, so check before most rides: road tyres roughly weekly, wider tyres every week or two.

These are starting points. Rider weight, tyre width, rim, and terrain all shift the ideal figure, so adjust in small 2–3 psi steps from a good first guess. The tyre sidewall shows a maximum (and often minimum) — stay within it.

A tubeless setup typically runs about 5–10 psi lower than the same tyre with an inner tube, because there is no tube to pinch-flat. Use a pump with a gauge, or a separate gauge — floor pumps are far easier to read than mini-pumps.

Cleaning & lubricating the chain

A clean, lubed chain is quiet, shifts well, and lasts far longer than a dry, gritty one. The order matters: clean and dry first, then lube — oiling a dirty chain just grinds the grit into the rollers.

1. Wipe: back-pedal the chain through a rag to lift the loose muck.
2. Degrease if needed: for a heavily soiled chain, use a chain-cleaning tool or a brush with a bike degreaser, then rinse gently.
3. Dry fully: lube won't cling to a wet chain — let it dry or wipe it down.
4. Lube: one drop on each roller as you back-pedal a couple of turns, then keep turning to work it in.
5. Wipe off the excess: run the chain through a clean rag. Lube belongs inside the rollers; anything on the outside only attracts dirt.

Choose lube for the conditions: dry (wax-based) lube stays cleaner and suits dry roads but needs reapplying more often; wet lube lasts through rain and mud but attracts more grime. Apply to the chain only — keep it off discs, rims and pads.

Chain wear — when to replace

Chains stretch as the pins and rollers wear (the metal wears, the links don't literally stretch). A worn chain then chews into the cassette and chainrings. Replacing a chain on time is cheap; letting it run on ruins the far more expensive cassette and rings too.

Measure with a chain-wear gauge (chain checker). The replacement point depends on how many sprockets the drivetrain has, because narrower chains tolerate less wear:

Past 1% you'll almost always need a new cassette as well, and possibly chainrings. If you don't have a gauge, a shop will check it in seconds. Signs of a worn drivetrain include skipping under power (especially on a fresh chain over a worn cassette) and gears that won't hold no matter how you adjust them.

Brakes

Brakes are not optional maintenance. Whatever the type, both should feel firm and stop the wheel well before the lever reaches the bar.

Rim brakes

• Check the pads for wear — most have grooves; replace before they're gone. They should hit the rim squarely, not the tyre, and not dive under the rim.
• Keep the braking surface of the rim clean; grit embedded in pads scores the rim.
• Replace worn pads and gritty cables; a spongy lever usually means cable stretch or worn pads.

Disc brakes

• Check pad thickness — replace when the friction material is down to roughly 1 mm (or per the maker). Worn-out pads damage the rotor.
• Keep rotors and pads free of oil. Contaminated pads squeal, lose power, and often can't be recovered — handle rotors by the edge and never spray lube near them.
• Hydraulic systems self-adjust for pad wear and rarely need attention beyond pads, but the fluid needs bleeding periodically (typically once a year or when the lever goes spongy).
• Mechanical (cable) discs need occasional cable and pad-gap adjustment as pads wear.
• A rhythmic rub often means a slightly bent or warped rotor; a light true with a rotor tool fixes most cases.

Gears & indexing

If shifting is hesitant or noisy, the cause is usually cable friction, indexing being slightly out, or a worn drivetrain. For a mechanical (cable) system:

• Barrel adjuster: if the chain is slow to climb to a bigger sprocket, turn the rear adjuster anticlockwise a quarter-turn at a time; if slow to drop, clockwise.
• Limit screws (H and L): set how far the derailleur can travel so the chain can't be thrown into the spokes or off the smallest sprocket. Adjust these only when the chain over- or under-shifts at the extremes.
• Cables: gritty or corroded inner cables and housing are the most common cause of vague shifting — replacing them transforms an old bike.
• Hanger: a bent rear derailleur hanger (the small replaceable bracket the mech bolts to) causes shifting that can't be dialled out. A shop can check its alignment.

Electronic systems (Shimano Di2, SRAM AXS, Campagnolo) are trimmed in micro-adjust mode from the shifter or an app rather than a barrel adjuster, and hold their tune far longer — see the old-vs-new guide.

Bolts & torque

Modern bikes — especially carbon ones — use light, precise parts that must be tightened to a specific torque, measured in newton-metres (Nm). Too loose and parts slip or come off; too tight and you crush a carbon bar or strip a thread. Most components have the figure printed right next to the bolt. A torque wrench is the one tool that pays for itself.

*Typical values only — always use the figure marked on the part or in the maker's manual, which overrides any general chart.

A simple service schedule

Ride more in winter salt, mud or rain and everything moves up the schedule — wet, gritty conditions are what wear a bike out.