Adjusting gears and brakes on an urban bike

Before touching anything: look at the whole setup

I lift the rear wheel and pedal by hand to listen for where the noise is coming from. Often the problem isn't in the gears but in a dry chain or a brake pad rubbing against the rim. I check that first, because adjusting the derailleur with a dirty chain is a waste of time: any tension I set will end up badly calibrated.

With the bike propped up and the wheel lifted, I turn the pedal forward and shift through each gear one by one. I note which sprocket it skips on and in which direction it does so. That detail alone already tells me whether the problem is the limit, the tension, or a stretched cable.

H and L limit screws

The two small screws on the derailleur mark how far the chain can go. The H controls the smallest sprocket and the L the largest. If the chain falls toward the spokes, the L limit is loose; if it comes off toward the frame, it's the H. I turn them a quarter turn at a time and test each time, without rushing, because a quarter turn too much already changes the behavior.

Before moving them, I mark the original position with a fine marker. If I get lost, I go back to the starting point and begin again. It's faster than trying to guess how much I turned.

Cable tension and the barrel adjuster

When the limits are fine but the middle shifts engage slowly, it's almost always cable tension. The barrel adjuster on the handlebar lets you correct it while riding: I turn it half a turn, test, and keep going until every shift engages cleanly. If the cable is already stretched from so much use, there's no other option but to loosen the derailleur screw, tension it by hand, and tighten it again.

A mistake I made several times: over-tightening. The shift goes up fast but the chain is forced and makes noise on the middle sprockets. The right tension is the minimum that makes the shift engage without hesitation.

V-brake brakes: centering and checking the pads

The brake pads must sit flat against the rim, not tilted or touching the tire. If one rubs on only one side, the brake is off-center: I loosen the mounting bolt, hold the arch centered, and tighten it again. Worn pads are replaced when the wear groove is almost no longer visible, not when they start braking poorly.

And something worth repeating: the rim is never lubricated. Oil on the braking surface ruins braking and stains the pads. If grease accidentally gets on it, clean it with alcohol and a cloth until the surface is dull again.

Minimal tools and a short test

For all of this, a set of Allen keys, a flathead screwdriver, a wire brush for the chain, chain oil, and a cloth are enough. Nothing specialized. I bought the oil a while ago and it still lasts; the cloth comes from old clothes cut up.

Before heading out onto the street, I do a short stretch on the sidewalk: I shift through all the gears, brake hard two or three times, and listen. If anything rubs, it shows up right away. It's better to find out there than in the middle of traffic.

The chain noise that isn't from shifting

When the chain sounds metallic on every pedal stroke, many people start moving the derailleur unnecessarily. It is almost always a lack of lubrication or a stretched chain. Before touching the screws, I clean with a brush, apply a few drops of oil, and pedal for a while. If the noise continues, then I do check the shifting.