Brake and gear adjustment: a precision guide

Adjusting brakes and derailleurs is one of the most common maintenance tasks on a bike. After a Canadian winter, cables stretch, housing compresses differently with temperature changes, and derailleur limits can drift. Even a new bike often needs adjustment after a few hours of use while cables bed in.

This guide covers basic adjustments for the most common systems: cable-operated Shimano and SRAM derailleurs, rim brakes, and mechanical disc brakes. Electronic systems (Di2, AXS) follow different procedures and are not covered here.

1. Cable brake adjustment

The principle is the same for all cable brakes (V-brake, cantilever, caliper): tension on the cable pulls a brake arm to press the pad against the rim. Adjustment sets cable tension for progressive braking with optimal lever travel.

Cable tension and lever travel

The ideal distance from lever to bar at full braking is about two to three fingers for V-brakes. If the lever hits the bar before effective braking, the cable is too loose. If you must squeeze hard from the start, it is too tight.

1. Loosen the cable clamp screw on the caliper (5 mm Allen on most Shimano models)
2. Pull the cable by hand until pad-to-rim gap is about 2 mm on each side
3. Tighten the clamp screw while holding tension
4. Fine-tune with the barrel adjuster: turn out to increase tension, turn in to reduce it

Pad alignment

The pad should contact the rim in the centre, with a slight toe-in of 1–2 mm forward. That angle reduces squeal common on V-brakes. On caliper brakes, loosen the centre bolt slightly and re-centre the caliper.

2. Rear derailleur indexing

Indexing synchronizes shifter positions with cassette cogs. Poor indexing causes skipping, noise, or slow shifts. Re-index after every cable replacement or after a crash that bends the derailleur hanger.

Derailleur hanger check

Before adjusting, confirm the derailleur hanger is straight. A bent hanger makes indexing impossible. From behind, the derailleur cage should be parallel to the cassette cogs. If not, use an alignment tool (Park Tool DAG-2.2) or have a shop correct the hanger.

Step-by-step indexing

1. Place the chain on the smallest cog (highest gear, cable slack)
2. Set the low limit (H screw): the guide pulley aligns with the small cog without rubbing the next cog
3. Shift to the largest cog (lowest gear)
4. Set the high limit (L screw): the guide pulley aligns with the large cog without the chain going into the spokes
5. Return to the small cog, clamp the cable with no tension, then pull by hand until you feel firm resistance
6. Tighten the cable clamp
7. Shift through all gears and adjust the barrel until each shift engages cleanly without delay or noise

B-tension adjustment

The B screw controls derailleur angle relative to the cassette. On large cassettes (34–46 teeth), more B-tension keeps the upper pulley clear of the largest cog. Aim for 1–2 mm between the upper pulley and the largest cog.

3. Front derailleur adjustment

The front derailleur is often neglected, but poor alignment causes chain rub and difficult shifts. Procedure varies by mount type (braze-on, clamp-on).

Front derailleur height and angle

The outer cage should sit 1–3 mm above the large chainring teeth. The cage should be parallel to the ring within about ±0.5°. Set height and angle before limits and cable tension.

Front limit screws

1. Place the chain on the small ring and largest cog
2. Set the L limit so the chain clears the inner plate without rubbing
3. Place the chain on the large ring and smallest cog
4. Set the H limit so the chain clears the outer plate without rubbing
5. Adjust cable tension for immediate upshifts without overshooting the large ring

4. Chain stretch and tension check

On a derailleur bike, chain tension is not user-adjustable—the rear derailleur spring maintains it. On a fixed-gear or singlespeed, tension is set by moving the rear wheel in the dropouts.

On derailleur bikes, correct tension means the rear derailleur keeps the chain taut in all gear combinations without the cage hitting its stop. If the derailleur lacks travel for large-large combinations, the chain may be too short—check length.

5. Fixed-gear and internal-gear hub maintenance

Internal-gear bikes (Shimano Nexus, Sturmey-Archer) need different care. The internal unit is sheltered from weather, which suits Canadian winter use. Maintenance mainly involves:

• Checking shift cable position per manufacturer marks on the hub (alignment point visible on Nexus models)
• Lubricating the hub at manufacturer intervals (typically every 3,000–5,000 km or annually)
• Adjusting chain tension by moving the wheel in the dropouts