Combined braking system in a motorcycle front wheel

A combined braking system (CBS), also called linked braking system (LBS), is a system for linking front and rear

brake A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Backgroun ...

s on a

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruisin ...

or scooter. In this system, the rider's action of depressing one of the brake levers applies both front and rear brakes. The amount of each brake applied may be determined by a proportional control valve. This is distinct from (conventional) integrated brakes, where applying pressure to the rear brake pedal only applies some braking force to the front brake.

Legal issues

In the United States, the law requires a motorcycle to have two separate braking systems, although there is no special requirement that the systems have separate controls. By contrast, a car is required to have only one braking system for dynamic braking (i.e. braking when moving), plus a separate parking brake. Since 2016, the EU requires CBS or

anti-lock braking system An anti-lock braking system (ABS) is a safety anti- skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses. ABS operates by preventing the wheels from locking up during braking, thereby maintai ...

(ABS) on all new scooters, motorcycles, tricycles, and quads below 125 cc. Since 1 April 2019, India requires CBS (or ABS) on all new two-wheelers below 125 cc. From 1 January 2024, Argentina will require CBS (or front wheel ABS) on all new on-road motorcycles between 50 and 250cc (or electric equivalents). Chile will require CBS (or ABS) on all new motorcycles from 50 cc to 149 cc or 4 kW to 11 kW from February 2026. From October 2025, Colombia will require CBS (or ABS) from 50 cc to 149 cc or 4 kW to 11 kW. From March 2027, Colombia will require CBS (or ABS) on all new motorcycles below 125 cc.

Examples of CBS

BMW Motorrad BMW Motorrad is the motorcycle brand of BMW, part of its Corporate and Brand Development division. It has produced motorcycles since 1923, and achieved record sales for the fifth year in succession in 2015. With a total of 136,963 vehicles sold i ...

uses a system called Integral ABS, in which the front brake lever operates both the front and rear brakes, while the brake pedal operates only the rear brake. In the inverse,

Honda is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan. Honda has been the world's largest motorcycle manufacturer since 1959, reaching a producti ...

's system that features both combined brakes and

anti-lock brakes An anti-lock braking system (ABS) is a safety anti- skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses. ABS operates by preventing the wheels from locking up during braking, thereby maintaini ...

is dubbed Combined ABS. In this system, the rear brake pedal operates both front and rear brake, and the front brake lever operates the front calipers, which in turn activates a secondary master cylinder to engage the rear brake. ABS modulators are installed on both the front and rear wheel. Honda's first street motorcycle with a combined braking system (then called Unified Braking) was the 1983 GL1100. This system was derived from a 1970s RCB1000 world endurance race bike.

made several variations of the LBS system with differing levels of complexity and integration. The Honda CBR1000F and CBR1100XX and

VFR800 The Honda VFR800 (Interceptor) is a sport touring motorcycle made by Honda since 1998. The model was the successor to the VFR750F and shares the V4 engine configuration with the Honda VF and VFR series. Fifth Generation: 1998–2001 VFR800Fi ...

featured what

called LBS II (now called Dual CBS), a system where both levers would activate both brakes through a system of secondary pistons and proportioning/delay valves. One front brake caliper was connected to a secondary master cylinder, and the caliper was allowed to rotate slightly to apply pressure to the piston in that secondary master cylinder. Braking force was translated into pressure that was sent to the rear brake cylinder. Only the two outer pistons in the front brake calipers were directly activated by the brake lever; the center piston received pressure from the rear pedal via the proportioning and delay valve. From 2009 the

Honda CBR1000RR The Honda CBR1000RR, marketed in some countries as the "Fireblade" (capitalized as FireBlade until the 2000s), is a liquid-cooled inline four-cylinder superbike, introduced by Honda in 2004 as the 7th generation of the CBR series of motorcycles ...

and

CBR600RR The Honda CBR600RR is a sport bike made by Honda since 2003, part of the CBR series. The CBR600RR was marketed as Honda's top-of-the-line middleweight sport bike, succeeding the 2002 Supersport World Champion 2001–2006 CBR600F4i, which was ...

sport bikes are optionally equipped with an integrated Dual CBS and ABS system which uses an

electronic control unit An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a car or other motor vehicle. Modern vehic ...

to distribute hydraulic pressure between front and rear brakes. The combined anti-lock braking system is called C-ABS.

References

{{Chassis control systems Motorcycle technology