page_title: Bicycle brake
section_title: Side-pull caliper brakes
hierarchical_section_title: Bicycle brake / Brake types / Rim brakes / Types of rim brakes / Side-pull caliper brakes
caption_attribution_description: English: Taken by Andrew Dressel
context_page_description: A bicycle brake reduces the speed of a bicycle or prevents it from moving. The three main types are: rim brakes, disc brakes, and drum brakes.
  Most bicycle brake systems consist of three main components: a mechanism for the rider to apply the brakes, such as brake levers or pedals; a mechanism for transmitting that signal, such as Bowden cables, hydraulic hoses, rods, or the bicycle chain; and the brake mechanism itself, a caliper or drum, to press two or more surfaces together in order to convert, via friction, kinetic energy of the bike and rider into thermal energy to be dissipated.
context_section_description: "Single-pivot side-pull caliper brakes" consist of two curved arms that cross at a pivot above the wheel and hold the brake pads on opposite sides of the rim.  These arms have extensions on one side, one attached to the cable, the other to the cable housing.  When the brake lever is squeezed, the arms move together and the brake pads squeeze the rim.
  These brakes are simple and effective for relatively narrow tyres but have significant flex and resulting poor performance if the arms are made long enough to fit wide tyres. If not adjusted properly, low-quality varieties tend to rotate to one side during actuation and tend to stay there, making it difficult to evenly space brake shoes away from the rim. These brakes are now used on inexpensive bikes; before the introduction of dual-pivot caliper brakes they were used on all types of road bikes.
  "Dual-pivot side-pull caliper brakes" are used on most modern racing bicycles. One arm pivots at the centre, like a side-pull; and the other pivots at the side, like a centre-pull.  The cable housing attaches like that of a side-pull brake.
  The centering of side-pull brakes was improved with the mass-market adoption of dual-pivot side-pulls (an old design re-discovered by Shimano in the early 1990s). These brakes offer a higher mechanical advantage, and result in better braking.  Dual-pivot brakes are slightly heavier than conventional side-pull calipers and cannot accurately track an out-of-true rim, or a wheel that flexes from side to side in the frame during hard climbing.  It is common to see professional racers climbing mountains with the quick-release undone on the rear brake, to eliminate drag from this source.
caption: Dual-pivot caliper brake.
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