Adjusting your gears step by step (and when to see a shop)

Short answer: a basic rear derailleur adjustment is done with the cable barrel adjuster and the H and L limit screws, usually in 10–15 minutes. But if the derailleur "skips" or will not reach the end gears despite adjustment, the culprit is most often a bent derailleur hanger or a worn cable — and that is a job for a workshop.

Start by diagnosing. Lift the rear of the bike (or use a stand) and turn the cranks while shifting. Note whether the chain moves to the next sprocket immediately or with a delay, and whether it slips off the cassette. Delayed, "lazy" shifts are usually about cable tension; slips at the edge of the cassette are about the H/L limits.

The tools are simple: usually an Allen key (typically 5 mm) for the cable pinch bolt and a small Phillips screwdriver for the limit screws. The barrel adjuster at the derailleur or shifter is turned by hand, no tools needed.

Tension adjustment (rear): when the chain is slow to climb to a larger sprocket (easier gear), add tension — turn the barrel adjuster half a turn anticlockwise and check. When it is slow to drop to a smaller one, reduce tension (barrel the other way). Adjust in half-turns and check each time under load on the cranks.

The H and L limit screws set the derailleur's end positions. The H (high) screw limits travel at the smallest sprocket, L (low) at the largest. Set them so the chain runs quietly in the end gears and does NOT drop off the cassette or between the cassette and the spokes. This is set rarely — usually only after disassembly or when something has drifted.

The front derailleur follows similar logic: it has its own inner and outer limits and cable tension. The key things are the cage height and its alignment parallel to the chainrings. Front adjustment can be more sensitive than the rear — if the chain rubs the cage despite your attempts, check the manufacturer's guide or leave it to a shop.

When is it a workshop job? When, after a correct tension and limit adjustment, the derailleur still skips — suspect a bent hanger (the part joining the derailleur to the frame). The hanger is checked with a special gauge and straightened or replaced; doing it by eye easily makes things worse. Also for a shop: a worn, stretched cable and outer, a badly worn cassette or chain (adjustment alone will not help), and electronic groupsets, which need a software calibration.

A safety rule: adjust in small steps, note how far you turned the barrel, and ride a few metres under load before calling it done. If you are unsure, or the bike has brakes or setups you would rather not touch, a short shop visit is cheaper than repairing a damaged drivetrain. You can find a workshop in our directory by filtering on city and service.