Bike maintenance basics: the checks that prevent the expensive repairs

The M-check is the standard pre-ride inspection, and it is a memory trick more than a procedure: walk the shape of a letter M over the bike, from the front hub up to the bars, down to the bottom bracket, up to the saddle, down to the rear hub. Follow the shape and you cannot skip anything that matters. It takes about a minute once you know it.

1. 1

   Front wheel

   Spin it: it should run true and quiet. Squeeze opposite pairs of spokes — even, none loose. Check the tyre for cuts, embedded flint and worn tread, and the pressure against tyre width and pressure . Make sure the wheel is secured: quick-release closed with real force, or thru-axle fully wound in.

2. 2

   Fork and front brake

   Pull the front brake on and rock the bike forwards. No knocking from the headset, no movement in the fork legs. The lever must stop well short of the bar. Look at the rotor for oily marks and at the pads for remaining material. If the lever feels spongy or reaches the bar, do not ride it.

3. 3

   Bars and stem

   Grip the front wheel between your knees and try to twist the bars. Nothing should move. Check the bars sit straight and the levers have not rotated. If a bolt needs tightening, do it to the torque printed on the part, and use a torque wrench on any carbon bar, stem or steerer.

4. 4

   Bottom bracket

   Push a crank arm side to side. Any rocking is a bearing or a loose crank bolt, and both get worse quickly. Spin the pedals backwards and listen: a dry chain sounds like sand, a stiff link ticks once per revolution.

5. 5

   Saddle and seatpost

   Try to twist the saddle and to push its nose up and down. It should be solid and level, at the height you set in saddle height and bike fit . Check the post’s minimum-insertion mark is still hidden inside the frame — if you can see it, the post is too far out — and tighten to the torque printed on the part.

6. 6

   Rear wheel and drivetrain

   Repeat the front wheel checks, then pull the rear brake and rock the bike backwards. Look at the cassette teeth for a shark-fin profile and at the chain for rust or stiff links. Check the axle is tight and the gear hanger is not visibly bent.

Maintenance schedules fail because they ask for an hour on a Sunday. This one is built around ten minutes a week, because ten minutes a week is what prevents the repairs below. Treat the distances as a guide: a winter of wet road grit wears a drivetrain faster than a dry summer at twice the mileage.

An e-bike adds to this list and takes nothing away. The extra weight and the motor torque wear chains, cassettes and brake pads faster, so move those inspections up a band: the assisted bikes here weigh 22.8 to 27.3 kg before you load them. Battery care is its own subject, in the e-bike range guide .

A chain does not stretch. The pins and rollers wear, each joint gains a fraction of a millimetre, and the chain gets longer. A longer chain no longer sits in the valleys between the cassette teeth, so it grinds new valleys to match itself. Ride it long enough and the cassette is shaped to the worn chain — at which point a new chain skips on it and you replace both.

That is the whole cost argument, and it is stark. A chain is a €25 part you can fit yourself with a chain tool and a quick link. A chain and cassette together is a €120 job. Standing between them is a chain checker costing about €10 and thirty seconds a month.

• Replace at 0.5% wear on 11- and 12-speed. The chains are narrower and the cassettes cost more, so the window is tighter.
• Replace at 0.75% on 8-, 9- and 10-speed. Past 1%, assume the cassette has gone too and check the chainrings.
• With a drop-in checker: if the 0.5 pin drops in, order a chain. If the 0.75 pin drops in, order a chain and expect to need a cassette.
• Check monthly, more often through a wet winter. Grit does the damage, not distance.

A clean, lightly lubed chain is quieter, shifts better and lasts longer. An over-lubed chain is worse than a dry one, because lube on the outside collects grit and becomes grinding paste. The goal is lube inside the rollers and nothing on the outside: wipe the chain with a rag while backpedalling, put one drop on each roller as it passes, leave it a few minutes, then wipe the outside until the rag comes away nearly clean. Only reach for degreaser when the chain is visibly black, and never point a pressure washer at a hub, bottom bracket or headset — it drives water past the seals.

Tyres

Many tyres have small dimples moulded into the centre of the tread as a wear indicator; when they disappear, the tyre is done and the puncture rate climbs. Without dimples, look for a flattened square profile down the middle, a visible line of casing threads, cuts deep enough to see into, or a bulge anywhere. A sudden run of punctures is usually a worn tyre rather than bad luck. If only one is finished, put the better tyre on the front, where losing grip costs you most.

Brake pads, rotors and rims

Disc pads wear down to a thin layer of friction material on a steel backing plate. Judge the material, not the whole pad, and replace well before it reaches the plate — pad makers publish a minimum thickness, so use the figure for your pads rather than a guess. Metal on metal ruins a rotor costing several times the pads. Rim blocks have wear grooves moulded in: when the grooves are gone, so are the blocks. Rims wear too, and many carry a wear indicator; a visibly concave braking surface means the rim is finished and should be replaced rather than ridden.

Cassette, cables and hoses

Worn cassette and chainring teeth curl into a shark-fin shape, and the giveaway is a new chain skipping under load. Frayed strands at a cable end, or a gritty feel at the lever, mean the cable or housing is due. Hoses do not wear that way, but a lever gone spongy, or one that firms up only when you pump it twice, needs a bleed — and that is a shop job unless you have the kit.

There is no prize for doing everything yourself. Each job below needs either a tool that costs more than the service, or has a consequence you do not want to discover at speed.

• Hydraulic brake bleeding. It needs the right kit and the right fluid — mineral oil and DOT are not interchangeable, and mixing them destroys the seals. 43 of the 53 bikes here run hydraulic discs.
• Anything inside a brake caliper or lever, and any brake symptom you cannot explain. This is the place to ask rather than experiment.
• Wheel truing and spoke tension. A wheel can be pulled straight and left with wildly uneven tension, which fails later. It needs a stand and a tension meter.
• Bearing replacement — hubs, bottom bracket, headset, suspension pivots. Mostly pressed in, mostly needs specific tools.
• Servicing a suspension fork or shock, or anything involving a sealed damper.
• Any bolt on a carbon frame, bar, stem or seatpost if you have no torque wrench. Over-tightening crushes carbon; under-tightening lets it slip.
• Motor, battery and wiring faults on an e-bike. Diagnostics need the manufacturer software, and opening a battery pack is not a home job.
• A frame or fork you suspect is cracked. Do not ride it to find out.

Service load differs by bike, and it is worth knowing before you buy. A steel tourer built around mechanical simplicity asks less of you than a full-power e-bike with a motor, a battery and 25 kg working on its brake pads. That is part of the running costs covered in how to choose a bike , and worth weighing before the purchase rather than after.