How To Use A Road Bike Computer
So you’ve bought a brand new cycling computer but you’re not really sure how to get the most out of it.
Don’t worry though, we’ve all been there, and being confronted with all this terminology and training data can be extremely daunting to the point where you may even find yourself asking “what is a bike computer?”
In this article, we’re going to cover how your GPS bike computer works and discuss what features are important from the data it collects right the way down to whether you have wireless connectivity or a colour display.
As a side note – if you’re looking for a new bike computer for a reasonable price then check out our guide on the best budget bike computer.
So, now you know what you’re in for, let’s jump into the article.
How Does A Bike Computer Work?
Bike computers use small sensors that attach to the wheels and forks of your bike (and in the case of cadence sensors, to the chainstay and pedal crank) and record the frequency of each wheel revolution which then gives you data such as speed, distance, etc.
Usually, a magnet is attached to a spoke on the front wheel and a sensor to one of the fork legs. Normally, you’ll have to calibrate your bike computer with your wheel size. The instruction manual is likely to tell you how to do this but if you need additional help then check out our article on how to measure your wheel for a bike computer.
This is so that each time the magnet passes the sensor, the computer recognizes the distance traveled by the wheel and so it can also measure the speed according to the frequency of wheel rotation. Then you can easily see all the data on your display. You can also hook up a heart rate monitor to measure your bpm (beats per minute).
From these inputs, along with GPS and accelerometer readings, bike computers can record maximum speed, distance, cadence (the number of pedal rotations per minute measured with a cadence sensor), calories burned, elevation, heart rate, temperature, and more.
While most cycling computers offer real-time onscreen information (for example, speed and heart rate), it’s often after the ride that they become most useful and you can then use the different data fields to judge how much you’re cycling is improving which is vital if you’re training for an event with other competitive riders.
Other Tools Used With A Bike Computer
When you cycle you exert power by using a force over a distance. Pedal power meters measure how hard you’re pedaling and multiply it by how much you have pedaled. Most of the sensors that measure these things are embedded into your cranks or pedals. They communicate their calculations back to the bike computer via ANT+ or Bluetooth Low Energy.
Cadence sensors are pretty much the same as speedometers. They can use magnets, orientation sensors, and sometimes use pressure sensors, but they time how long it takes your pedals to rotate instead of timing the wheels.
Heart Rate Monitor
Heart rate monitors use one of two different techniques. They either sense the electrical signals coming from your heart as it beats, or they use LEDs and receptors to detect your blood flow. If your heart rate unit wraps around your chest it is most likely measuring electrical signals. However, if you are using a smartwatch to track your heart rate, they tend to use the LED method.
Features On Your Bike Computer
Many bike computers offer different features, here are the kinds of things you might see upon device setup or in your bike computer’s manual and what they all mean or offer.
Current speed – The speed you’re traveling at
Maximum speed – The highest rate of speed you have attained
Average speed – Measures the average rate of speed over the extent of a trip
Weather information – Gives you updates on current weather and future forecasts
Elapsed time – The actual time taken
Odometer – Measures the distance traveled
Calorie counter – Gives an estimate of how many calories you have burned
Turn-by-turn navigation – Similar to a car in that it offers live updates on your location
GPS Location – Offers maps of your location and where you’re heading.
Clock – This shows how long you have been riding or how long you have left if you set a timer
Colour display – Your display will appear in color as opposed to black and white
Wireless compatible – Doesn’t require a wired connection to operate (most units are wireless)
Backlight – Keeps your display well lit when it’s dark
Long battery life – how long the bike computer can stay on before running out of battery
Cadence compatible – Can accommodate the use of a cadence sensor
Strava integration – Tracks exercise which incorporates social network features.
Electronic shifting integration – small electric motors to shift the gears instead of metal cables
Altimeter – Calculates your altitude or distance above sea level
Muscle oxygen (Moxy) sensor – a small, wearable sensor that monitors oxygen levels in the muscles
Touchscreen – Can control bike computers by touch
Heart rate – A sensor that detects your heart rate or beats per minute (bpm). Usually sold separately
Wi-Fi – Can connect to the internet via wifi
Rider to rider connectivity – allows you to interact with other bikers from a distance
Consider The Brand
When you buy bike computers you’re investing in not only the device itself but the brand name and its chosen interface. Many brands have their own apps, UIs (user interface), and websites that connect to your bike computer and compile your data.
For example, if a Garmin Edge computer is better than a Cateye Velo, you need to consider if you like the Garmin Connect web portal and smartphone app better than the Cateye web portal and smartphone app. This is down to personal preference as many brands offer most of the same features but their user interfaces, accessibility, etc. will vary.
Positioning Your Bike Computer
Having the sensor on your front or back wheel won’t make too much difference unless you have a wired sensor. In which case, there are a few things you may want to consider.
Firstly, it’s easier to route a wire through the front wheel so if you want as little set up as possible, then stick the sensor on your front wheel. A downside to this is that you’ll have excess wire length that will need to be wrapped around your fork as the wire provided will always be long enough to reach the back wheel also.
If you want the wire to look a little neater then you can go to the extra trouble of routing it to your rear wheel but as we said before, either way, it makes no difference to you or your bike computer’s performance.
Rim and Hub
When you put the sensor towards the hub (the middle of the wheel), the magnet on the spoke moves past the sensor much more slowly than it would if it were to be mounted closer to the rim. This will mean it takes longer to pass the sensor and so the sensor has a better opportunity to read the changing magnetic field. This results in a more accurate reading, especially at higher speeds.
However, if the magnet is close enough to the hub, that tendency won’t be too strong, but much further out, and it will fly out to the rim. So, you may be better off mounting it as close to the rim as possible.
What To Do If Your Bike Computer Doesn’t Work
The most likely problem you’re having is that the magnet isn’t getting close enough to the sensor. The magnet will often rotate around the spoke or move up and down it.
Other common problems are a damaged wire or screen, in which case going to a bike shop is probably the best course of action to get it repaired.
Alternatively, your battery may be dead. Cheap batteries are often used in bike computers and they only last for so long. Fortunately, they don’t cost too much to replace.
Frequently Asked Questions
What does a bike computer do?
Bike computers attach to your handlebars or stem and display a range of real-time information on your speed, distance, trip time, and much more. They have increased in popularity due to the growth in performance software, such as Strava, providing a world of statistics and data for cyclists everywhere.
Can I use Strava as a bike computer?
Strava turns every iPhone and Android into a sophisticated running and cycling computer. Start Strava before an activity and you can track your favorite performance stats, and afterward, look at your data.
How does a bike computer calculate speed?
Distance is determined by counting the number of rotations, which translates into the number of wheel circumferences passed. Speed is calculated from distance against lapsed time period using the circumference of the wheel and the time it took to make one rotation.
Will a wireless bike computer work on the back wheel?
The short answer is that you can put a bike computer on a rear wheel, but it must be specifically designed to work from that position. In other words, not all bike computers can work on a rear wheel.
Why is my bike computer not working?
The most common problems are fairly easy to fix. There are three basic causes of the vast majority of cycle computer malfunctions: Battery problems, wiring problems, and misalignment between the magnet and the sensor.
Where do you mount a computer on a mountain bike?
The stock mount that comes with many cycling computers allows the unit to be mounted in a variety of locations, including the handlebar, on top of the stem, or even on the top tube. Some enduro racers prefer the top tube location, as it keeps the computer safe in the event the bike goes tumbling away from them.