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Cycling Computers 101

close up of road bike handlebars with a garmin cycling computer and a blackburn bag attached

Cycling Computers 101

Most of us had the experience of learning how to ride a bike at a young age and racing down the street at top speed, imaging how fast we were going. Well, for riders who want to gather speed and other information about their ride, a cycle computer (or cyclometer) is just the ticket. Cycling computers are small devices that normally mount on the handlebars of the bike and use various sensors to measure -- at the very least -- speed, trip distance, trip length and time. Some advanced cycling computers provide advanced features as well.

This guide will explain the basic functionality of cycling computers, go over the features and price range on the market, and share some tips about how to use a cycle computer.

Setting Up The Sensors

Bike computer sensor on wheel

Most cycling computers operate by means of a pair of sensors. The first sensor is a small, passive device that screws onto the spokes of your bike wheel. The second sensor is a slightly larger device, sometimes battery powered, which mounts onto the fork or rear stays of your bike.

These sensors should be lined up, so that when you ride your bike, the sensor on the wheel rotates directly past the sensor on the frame. When programmed with the diameter of your wheel, this allows the cycling computer to calculate your speed based on the RPMs of the wheel.

The cycle computer itself is a small device, usually rectangular, which mounts on the top of the handlebars and connects to the sensors most often via a wireless connection. A small liquid crystal display allows the cycle computer to display information at a glance. Cycling computers usually feature a single button that is used to toggle through the different functions, set clocks and set preferences for imperial or metric measurements.

A Wealth Of Information


While you ride, most cycling computers show your speed as the default display item. Some units with bigger screens show multiple items at once: speed, distance traveled, current time, etc.

Some cycling computers also feature other sensors which measure cadence (this requires a small sensor/magnet combination to be mounted on the crankarm and frame), altitude to measure climbing and descent data, current incline, power output, temperature, or even heart rate. These sensors can sometimes calculate average speed and can function as a stopwatch.

The most advanced sensors on the market can even be attached to sensors on your body to show blood oxygen levels. These are used by professionals and serious racers to keep their body operating at exactly the level of exertion they have planned out before the race and can also be used to determine training intensity.

Some advanced cycle computers feature GPS navigation technology, advanced software or web applications to track data, customized workout creations, calorie calculators and more. These expensive devices may also use touch screens for ease of navigation while riding.

Build Quality And Battery Life


Larger, more expensive cycle computers have more features, but this generally comes at the expense of battery life. The most advanced cycling computers on the market have 20-30 hours of battery life and use rechargeable lithium-ion batteries. By comparison, the cheap end of the market uses watch batteries that can be used for months on end before replacing.

Most cycling computers are built tough, with waterproof casings and durable construction, so they can withstand a drop or two. Look for extra tough models for mountain biking. Accidentally running over your $30 cycling computer may not be such a big deal, but having one of the more expensive computers will likely influence you towards being careful.



General purpose cycle computers with basic features like the ability to track speed, trip distance, trip time, and clock can be found for as little as $15-$30. These are great for casual riders looking to measure their speed and even for bike tours.

Cadence and/or heart rate compatibility, altimeter functionality begins to be found on computers costing around $80, while GPS functionality along with the ability to measure power output starts around $160. The top-end cycle computers on the market cost over $400 and feature color touchscreens, precise GPS tracking, and wide sensor compatibility.

These more expensive models are ideal for people training or racing seriously, as they provide invaluable feedback on performance at the very moment it is occurring. It is also nice to know that some models can be used with two bikes, which makes it easy to buy an extra sensor and swap the computer between cycles when you choose a different ride. Not all computers have this feature, so make sure to check before you buy.

Additional sensors to transmit data on heart rate, cadence, or power output are often sold separately from the cycle computer unit itself, and cost in the range of $20-$60 each.

It is also important to know that some new sensors on the market can be used to interface with your smartphone via downloadable apps. This allows you to simply mount your phone on your bike, and use the high-quality display screen you always have with you as a cycling computer as well. Just be careful, as phones aren't designed with this is mind and a single good tumble off a moving bike can put a phone out of commission quickly.