Bike basics: five fixes you can do at the kerb

Commuter bike against a brick wall with a compact tool on the saddle
Kelvin Tools

Modern bikes are held together with a handful of hex and Torx bolts in a handful of sizes. That makes most of the everyday adjustments quick, provided you have the right bits and a tool that fits in a jersey pocket or a saddle bag.

The sizes that matter

Four, five and six millimetre hex cover most stems, seat clamps, bottle cages and racks. Torx T25 is common on disc brake rotors and some stems; T15 and T20 appear on racks and accessories. A compact ratchet with sockets and bits, such as the Kelvin PakRatchet, reaches into tight spots a plain L-key cannot. It carries seven 6-point sockets, four 25 mm bits (Square #2, Phillips #2, T15, T20) and a ratchet with in-grip storage, in a carbon fibre body with stainless springs. Check the bolt sizes on your own bike against what the tool carries; metric and SAE versions exist.

1. Saddle height

Sit on the saddle with your heel on the pedal at the bottom of the stroke; your leg should be straight. Loosen the seat clamp, adjust, retighten. Many clamps have a torque figure stamped on them; snug with a short tool is usually right.

2. A loose stem or handlebar

If the bars twist or the stem turns separately from the wheel, stop riding until it is fixed. Loosen the two stem bolts at the back, line the stem up with the front wheel, tighten them alternately a quarter turn at a time. Never ride with a stem you can move by hand.

3. The rattling rack or bottle cage

Rack bolts work loose constantly. Snug them, and if a bolt keeps loosening, a drop of blue thread locker fixes it for the season.

4. A crooked brake lever

One bolt under the lever clamp. Loosen slightly, rotate the lever so your wrist is straight when you reach for it, tighten.

5. A slipping seatpost

Clean the post and the inside of the seat tube, apply a thin layer of grease (or carbon paste for carbon posts), reinsert and tighten the clamp. If it still slips, the clamp may be worn.

What is not a kerb job

Brake pads, derailleur indexing, headset bearings and anything hydraulic. Those want a stand and a workshop, or a shop.

See the Kelvin PakRatchet

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