A cyclocomputer, cycle computer, cycling computer or cyclometer is a device mounted on a

bicycle A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist. Bic ...

that calculates and displays trip information, similar to the instruments in the

dashboard For business applications, see Dashboard (business). A dashboard (also called dash, instrument panel (IP), or fascia) is a control panel set within the central console of a vehicle or small aircraft. Usually located directly ahead of the driver ...

of a car. The computer with display, or ''head unit'', usually is attached to the handlebar for easy viewing. Some

GPS watch A GPS watch is a device with integrated GPS receiver that is worn as a single unit strapped onto a wrist, in the manner of a bracelet. The watch can have other features and capabilities depending on its intended purpose and be a smartwatch. GPS wa ...

es can also be used as display.

History

In 1895, Curtis H. Veeder invented the ''Cyclometer''. The Cyclometer was a simple mechanical device that counted the number of rotations of a bicycle wheel. A cable transmitted the number of rotations of the wheel to an analog

odometer An odometer or odograph is an instrument used for measuring the distance traveled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two (electromechanical). The noun derives from ancient Gr ...

visible to the rider, which converted the wheel rotations into the number of miles traveled according to a predetermined formula. After founding the Veeder Manufacturing Company, Veeder promoted the Cyclometer with the slogan, ''It's Nice to Know How Far You Go''. The ''Cyclometers success led to many other competing types of mechanical computing devices. Eventually, cyclometers were developed that could measure speed as well as distance traveled.

Basic operation

The head

A basic cyclocomputer with a wheel speed sensor may display the current speed, average speed, maximum speed, trip distance, trip time, total distance traveled, and the current time. More advanced models with additional sensors and storage may display and record

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

, incline (

inclinometer An inclinometer or clinometer is an measuring instrument, instrument used for measuring angles of slope, elevation, or depression (geology), depression of an object with respect to gravity's direction. It is also known as a ''tilt indicator'', ' ...

heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...

, power output (measured in

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

) and

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

as well as offer additional functions such as pedaling

cadence In Western musical theory, a cadence (Latin ''cadentia'', "a falling") is the end of a phrase in which the melody or harmony creates a sense of full or partial resolution, especially in music of the 16th century onwards.Don Michael Randel (1999) ...

, a

stopwatch A stopwatch is a timepiece designed to measure the amount of time that elapses between its activation and deactivation. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stop clock. ...

and even

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

navigation and video data overlay synchronization. They have become useful accessories in

bicycling Cycling, also, when on a two-wheeled bicycle, called bicycling or biking, is the use of cycles for transport, recreation, Physical exercise, exercise or sport. People engaged in cycling are referred to as "cyclists", "bicyclists", or "bike ...

as a

sport Sport pertains to any form of Competition, competitive physical activity or game that aims to use, maintain, or improve physical ability and Skill, skills while providing enjoyment to participants and, in some cases, entertainment to specta ...

and as a

recreational Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure ...

activity. The display is usually implemented with a

liquid crystal display A liquid-crystal display (LCD) is a flat panel display, flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liqui ...

, and it may show one or more values at once. Many current models display one value, such as current speed, with large numbers, and another number that the user may select, such as time, distance, average speed, etc., with small numbers. The head usually has one or more

buttons A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole. In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, ...

that the user can push to switch the value(s) displayed, reset values such as time and trip distance,

calibrate In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known a ...

the unit, and on some units, turn on a back light for the display. Most displays are navigated by pressing buttons and high-end models use a capacitive touch screen to navigate screens and maps.

The wheel sensor

The older, traditional

sensors A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

have a magnet attached to a

spoke A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. The term originally referred to portions of a log that had been riven (split l ...

of either the front or rear

wheel A wheel is a circular component that is intended to rotate on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction wi ...

. A sensor based either on the

Hall effect The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was disco ...

, or on a magnetic reed switch, is attached to the

fork In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tines with which one can spear foods ei ...

or the rear of the

frame A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...

. The sensor detects when the magnet passes once per rotation of the wheel and time stamps or time codes the revolution count. Alternatively, a sensor may be attached to the wheel hub.

Distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

is determined by counting the number of rotations, which translates into the number of wheel circumferences passed.

Speed In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quanti ...

is calculated from distance against lapsed time period using the circumference of the wheel and the time it took to make one rotation.

The cadence sensor

To measure cadence (revolutions per minute of the crankarm), a magnet is mounted to the crankarm, and a sensor mounted to the frame. This works on the same principle as the speedometer function and measures the turning of the cranks and front chain ring.

Transmission

Some models use a wired connection between the sensor and the head unit. Other cyclocomputers, e.g. those used by competitive cyclists, transmit the data wirelessly from the sensor/transmitter to the head unit. Data can be exported to a SD card, computer, or phone and uploaded to an internet web service. Wireless cadence and speed sensors use wireless communication standards ANT + and Bluetooth Low Energy and can directly communicate with a smartphone application that also uses the phone's GPS, barometer, temperature, clock, and other sensors to create a more detailed picture, record, or map. Bicycle speed in KPH

Calibration

Once a new computer is installed, it usually requires proper configuration. This normally includes selecting distance units (kilometers vs. miles) and the circumference of the wheel. Since the sensor measures wheel rotation, different wheel sizes will translate to different measures of speed and distance for a given number of rotations. For more accuracy the bicycle (with the set cyclocomputer) must be ridden by the intended rider over an accurately measured distance. The computer's reading is then compared with the known distance and any necessary corrections made.

Additional information

Besides variables calculated from the rotating wheels or crank, cyclocomputers can display other information.

Gear

For integrated shifters on

racing bicycle A racing bicycle, also known as a road bike is a bicycle designed for competitive road cycling, a sport governed by and according to the rules of the Union Cycliste Internationale (UCI). Racing bicycles are designed for maximum performance ...

s, the gear can be read by the computer: Shimano's Flight Deck and Campagnolo's ErgoBrain work with their respective systems to detect the gearing. This allows indirect measurement of cadence. These systems do not have sensors on the crankset or cassette to determine what gear the bicycle is in. They work exclusively with the shifters, which may result in misleading information. Instead of knowing what gear the bicycle is in, they rely on sensing when the cyclist changes gears using sensors in the shifters. If the gear change doesn't actually happen, or the computer's sensors are too sensitive (e.g.: when braking with STI-style shifters), the information displayed is not accurate.

Performance

With additional sensors, other performance measurements are available: * A

heart rate monitor A heart rate monitor (HRM) is a personal monitoring device that allows one to measure/display heart rate in real time or record the heart rate for later study. It is largely used to gather heart rate data while performing various types of phy ...

can be integrated into the computer, using a chest strap sensor. * A power meter measures

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...

output in watts, using a torque sensor in the bottom bracket, pedals, or rear hub.

Environment

Some models also have sensors built into the head that measure and display environmental parameters such as temperature and altitude.

Cyclist power measurement

Some more sophisticated models are able to measure the rider's power in terms of watts. These units incorporate elements that measure torque at the crank, or rear wheel hub, or tension on the chain. This technology began in the late 1980s. (See

Team Strawberry Team Strawberry was a professional bicycle racing team that participated in experiments on human power/performance conducted by their primary sponsor, Balboa Instruments of Newport Beach, California. The Team was founded in 1988 by team captain Ala ...

for the early development and testing stages of this technology.)

Maps

Some cyclocomputers (such as the Garmin Edge, trimm One,

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Elemnt Bolt or Hammerhead Karoo) can be loaded with maps and can thus show the rider's position on the map, or provide turn-by-turn directions for a pre-determined route.

Electric bicycles

Most electric bicycles have a microcontroller in the motor controller to calculate input cadence or torque, adjust amperage, control the motors and send the display screen information. Often cyclists can select the level of power assist provided using the computer. The computer also monitors the speed and can deactivate the motor for braking or if required by law (for example, in many countries

pedelec A pedelec (from pedal electric cycle) or EPAC (''electronically power assisted cycle''), is a type of low-powered electric bicycle where the rider's pedalling is ''assisted'' by a small electric motor. However, unlike some other types of e-bi ...

bikes cannot use motor assist above 25 km/h).

References

{{commons category, Cyclocomputers American inventions

Computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...