Ten Minutes That Tell You Whether a Second-Hand Bike Is Worth Buying

There is a settled way of talking about buying a used bicycle. It is worth asking how much of it survives contact with the detail.

Start with the frame, because nothing else matters if it is bent

Look along the frame from front and rear, checking that the fork legs are even and the rear triangle sits square to the wheel. Run a finger along the underside of the down tube behind the head tube, which is where a front impact leaves a ripple or crease. Check every weld and tube junction for hairline cracks, paying most attention to the head tube, the seat tube junction and the dropouts.

Rust on the surface is cosmetic, but rust bubbling under paint or flaking inside the seat tube suggests corrosion that has been running for years. A bent or cracked frame is where you stop, because the repair usually costs more than the bike is worth.

Wheels, which are the next most expensive item

Lift each wheel and spin it, watching the gap at the brake pads or frame to see how far it wanders side to side. Small wobbles are a truing job, but a visible kink or a flat spot at one point means the rim itself is damaged.

Mid-traffic, squeeze pairs of spokes around the wheel, since one noticeably loose or a missing spoke means the wheel needs work before it is safe. On a rim-braked bike, check the braking surface for a concave groove or a visible wear indicator, because a worn rim can fail suddenly. Grab each wheel at the rim and rock it sideways to feel play in the hub bearings, which is adjustable on some hubs and terminal on cheap ones.

The drivetrain and how worn it is

Lift the chain away from the front chainring at the three o'clock position, and if it pulls clear of the tooth tips it is badly worn. A chain that worn will have already reshaped the sprocket teeth, so budget for a chain and cassette rather than just a chain.

Look at the sprocket teeth from the side, since worn teeth develop a hooked, shark-fin profile instead of a symmetrical one. Turn the pedals backwards while shifting through the gears, listening for a rear mech that hesitates or a bent hanger pulling the chain off line. None of this is expensive to put right, and quoting it back to the seller is the easiest money you will save.

Bearings and the parts you cannot see

Hold the front brake and rock the bike forwards and backwards, feeling for a knock at the headset that indicates loose or worn bearings. Turn the bars slowly with the front wheel off the ground, feeling for notchiness that means the headset bearings have indented their races.

Grab a crank arm and push it sideways towards the frame and away, since any play there points at the bottom bracket. Spin the cranks backwards with the chain removed from the chainring if possible, listening for grinding rather than a smooth quiet rotation.

Bearings are cheap and labour is not, so several bad bearings on a low-value bike change the sums considerably.

Provenance and the awkward question

Ask directly how long they have owned it, where they bought it and whether they have a receipt, and watch how comfortable the answer is. Stolen bikes are a large and well-documented market, and buying one funds the theft and may leave you with nothing if it is traced.

Check the frame number against any national or community bike registry available where you live before handing over money. A price far below the going rate for the model, combined with vagueness about history, is the pattern worth walking away from. Meeting at the seller's home address rather than a car park is a small filter that removes a lot of risk.

Frames, sizes and riding positions vary enormously; borrow before you buy wherever you can.

Ride it before you decide

Set the saddle to roughly your height first, since judging a bike from a badly set position tells you nothing useful. Ride it slowly with hands off the bars if the road is safe and empty, because a frame pulling persistently to one side is a bad sign. Brake hard from walking pace with each brake in turn, then check that both wheels lock and neither lever pulls to the bar.

Shift through every gear under light pedalling load and count how many are usable rather than how many exist. A bike needing a chain, cables, brake pads and a service is normal and cheap, and a bike needing wheels and bearings usually is not.

The takeaway

Pay for a straight frame and good wheels, and treat everything else as a shopping list.

Most of riding well is being boring and predictable to everyone else on the road.