Bike computers

Draadloze waterdichte fietscomputer

A digital bike computer that works wirelessly and is waterproof, for riders who want speed and distance without cables on the bike. It is an unbranded product, so you will need to read the product page for many details.

What you get

Digital bike computer
Wireless connection
Waterproof according to the title

Why a bike computer?

A bike computer gives you numbers to steer by. Speed and distance let you pace a ride, and cadence and heart rate make training more targeted. These units are small, light and built to last for years on your bars.

With a magnet sensor, a small sensor counts how often a magnet passes it on your spoke or hub. The computer multiplies that by the wheel circumference you enter, about 2100 mm for a 700x25c wheel. If your circumference is 20 mm off, your distance is off by about 1 percent. A GPS measures distance and speed using satellites. That is usually accurate to within 1 to 2 percent on distance, but tunnels, dense forest and tall buildings disturb the signal, and the speed reading reacts a little more slowly.

For altitude there are two methods. A barometer measures air pressure and converts it. It shows small height changes quite accurately, to within a few metres, but weather moves the pressure, so the absolute value drifts over a day. GPS altitude comes from satellite positions and is far less accurate, often tens of metres out. If you want climbing metres you can trust, pick a model with a barometer.

A simple magnet model needs little upkeep and its battery lasts a season. A GPS computer stores your ride, follows a route and syncs with an app, but it needs charging.

How bike computers compare

How a unit measures decides how accurate speed and altitude are.

Type	Speed and distance	Altitude	Battery	Setup
Wired with magnet	Very stable if circumference is right	Usually not available	About a year (coin cell)	Route cable, fit magnet
Wireless with magnet	Good, but interference can occur	Sometimes with barometer	Months to a season	Align sensor and magnet
GPS computer	Within 1 to 2% on distance, slower speed	GPS altitude, tens of metres off	About 15 to 30+ hours	No circumference needed
GPS with barometer	As GPS, even under trees	Barometer, accurate to a few metres	About 15 to 30+ hours	Calibrate altitude once

Guideline values. Each model works a little differently.

Choose it if

You want a simple computer without wires on your bars
You ride in the rain and want a waterproof unit
You want speed and distance without fuss and without constant charging.
You want to track climbing or cadence, and you choose a barometer on purpose.

Choose something else if

You want gps routes and navigation: look at a gps bike computer instead
You want to navigate or upload your ride. Then you need a bike GPS.
You swap bikes often and do not want to move a sensor and magnet each time.

How to use a bike computer

Mount the bracket
Fit the bracket to the bar or stem and click the computer in. Pick an angle you can read without moving your head.
Place sensor and magnet
Put the magnet on a spoke and the sensor on the fork, about 2 to 4 mm apart. With a GPS computer, skip this step.
Set the wheel circumference
Use the maker’s table, or roll the wheel one full turn and measure. A test over a known distance gives the best value.
Calibrate altitude
On a model with a barometer, set the altitude at a known point, such as home. Your climbing figures then stay reliable.
Choose your fields
Show a few fields at once, for example speed, distance and time. Look at the rest after the ride.

Good to know

The brand is not in the title, so check which features and which battery come with it
Check how the sensor and the bracket attach to your handlebar
Check the wheel circumference after every tyre change. A different tyre width changes it by a few millimetres.
A wireless sensor can drop out because of interference or a weak battery. Keep the distance to the computer short.
GPS altitude is an estimate. Do not compare your climbing too strictly with a unit that has a barometer.
Replace the battery in the sensor and computer in good time, before a long ride.

What you get

Why a bike computer?

How bike computers compare

Choose it if

Choose something else if

How to use a bike computer

Mount the bracket

Place sensor and magnet

Set the wheel circumference

Calibrate altitude

Choose your fields

Good to know

Also in this category