Bike computer

Cycling in the Information Age means more ride data is available to you than ever before. While the use of a smartphone to collect ride data is increasingly popular, a bike computer can still make sense for any rider, especially if you're a data-hungry enthusiast.

To get started, ask yourself:

  • What information do you want and how will you use it?
  • How much are you willing to spend?
  • What other functionality is important? Computer connectivity? Multi-bike options?

Shop REI’s selection of bike computers.

What Type of Rider Are You?

Your information needs often match the type of rider you are:

Casual cyclists usually just want to know the distance, speed and time: How far have I ridden? How fast am I going? How long did my ride take?

Enthusiast riders, commuters and touring riders often like a few more options such as trip distance, total odometer, average speed and maximum speed.

Competitive cyclists may want all of the above plus cadence, heart rate, elevation gained and power output.

Types of Data Devices

Bike computer

You have several options:

Bike computer: This is the sport-specific device that mounts to your bike. This article focuses primarily on this option.

  • Pros: Compact, weatherproof, stays on the bike, low profile mounting, less likely to get damaged in an accident.
  • Con: No versatility for other uses.

Shop REI's selection of bike computers.

Fitness monitor for cycling

Fitness monitor: A GPS sport watch with a bike mode can be mounted to your bike’s handlebars with an adaptor.

  • Pros: Use one device for more than one activity, weatherproof.
  • Cons: Usually less compact and a higher profile, thus more prone to damage in an accident. Easy to leave behind when going on a ride.
Smartphone

Smartphone: Use your GPS-enabled smartphone to run a cycling app.

  • Pros: Large, easy-to-read screen. Provides a mapping option as well as data capture and display.
  • Cons: Requires a mounting bracket to attach the device to your bike. Not weatherproof without an ancillary case. Running the GPS and keeping the screen awake consumes battery power quickly. Higher mounting profile and larger surface area increases the risk of damage in an accident.

Shop REI's selection of bike computers.

How Do Bike Computers Work?

You have several options in how a bike computer delivers information:

Types of Sensors

Magnetic: This consists of a magnet attached to a wheel spoke, which rotates past a sensor attached to the front fork. For a cadence sensor, the magnet is attached to a crank arm and the sensor is attached to a rear stay.

  • Pros: Cheaper, longer battery life. No need to recharge regularly.
  • Con: No GPS functionality.

 GPS: This uses a satellite receiver to convert GPS signals into ride data.

  • Pros: More data options, which can be transfered to a computer; customizable screens. Can be easily swapped between bikes.
  • Cons: Higher cost, heavier, needs regular recharging.

Types of Data Transmission

Wired: Magnetic sensor with a wire transmitting the signal to the display unit.

  • Pros: Cheaper, simpler, lighter.
  • Cons: Usually not swappable between bikes. Transmission wire can get caught and rip out, which is a higher risk on a mountain bike than a road bike.

Wireless: Magnetic sensor with a signal transmitter to the display unit. GPS sensors are intrinsically wireless.

  • Pros: Easier to install, no wires, cleaner look. 
  • Cons: More expensive - especially GPS units; heavier.

Other Bike Computer Features

These features can also influence your choice:

Backlight: Ride in the dark? A backlight feature makes your screen more readable than does shining a helmet light on the screen.

Battery life: GPS bike computers use a built in-rechargeable battery with a life of up to 20 hours; smartphones using a GPS and cycling app last about 5 – 8 hours. Magnetic units use 1 or 2 watch batteries, often a CR2032, which can last a couple of years.

Multiple data screens: Data may be restricted to a single screen or several screens you can scroll through with the push of a button. Screen options may be fixed or customizable.

Data transfer: Do you want to transfer data to training program software, website or a social fitness site? GPS models, including smartphones, cater to this.

Readability: How easy to read is the screen data? Magnetic units have a fixed font size. GPS models may have an option to change font size. A small font that is easy to read while stationary may be blurred by road vibration when on the move.

Additional mounts: Available for units that have multi bike functionality, aftermarket mounts can position the computer out in front of the handlebar. This is of benefit to cyclists losing near-distance focus. It also means less time with eyes averted from the road or trail when glancing down at the screen.

Multi-bike use: Some units, typically the higher-end GPS models, can be swapped between 2 or 3 bikes and save cumulative data for each bike in a separate file.

Budget

Price Range Bike Computer
Features
Up to $50 Basic magnetic-sensor wired models. Time, distance, speed.
$50 to $125 Magnetic-sensor wired or wireless models with additional options such as cadence.
$125 to $200 Advanced magnetic-sensor wireless models or basic GPS models. May include some performance and environmental data like heart rate, temperature and elevation.
 $200+ Advanced GPS models with customizable screens, a full range of data options and possibly a mapping option.

Bike Computer FAQs

Q: Which type is more accurate?

A: A dedicated GPS bike computer is more accurate and reliable than a smartphone with GPS and cycling app. A magnetic bike computer can be close in accuracy to a GPS unit provided that the code for your tire size is correctly entered into the setup menu.

Q: I have a magnetic type, but I’ve lost my wheel magnet.  Can I get another one?

A: Yes, go to REI or other local bike shop for a replacement wheel magnet.

Q: If my battery dies, do I lose my ride data?

A: No. You can recharge or replace batteries without losing ride data.

Q: My bike computer doesn’t work anymore.  What’s wrong with it?

A: There are several possibilities:

Sensor position: The wheel sensor may have been knocked out of position. Check the alignment and gap between the wheel sensor and the spoke magnet. (Applies to magnetic models.)

Battery: A magnetic wired model has a battery in the display unit. Replace it if it's more than 2 years old. A magnetic wireless unit also has a battery in the wheel fork transmitter. Replace it at the same time as the display unit battery.

Mount connection: The display unit may not be engaged correctly in the mount. Take it off and click it on again. (Applies to wired models.)

Wire connection: The wire in a wired model may have pulled loose from the mount or gotten worn from rubbing on the frame. Check the integrity of the wire. If it is faulty, you may need to replace the computer.

Shop REI’s selection of bike computers.

Smartphone photo by HF / Wikipedia Commons.