Bike and Byte — Bike Computer Guide | bikeandbyte.com
Compare wired, wireless and GPS computers by measurement source, sensor radio and setup effort.
A wired cyclocomputer reads a spoke magnet passing a fork-mounted sensor: speed equals wheel circumference multiplied by revolutions per second, and the circumference must be entered correctly — about 2110 mm for a typical 700x25c road tyre (ETRTO 25-622). Setup is a bracket on the bar plus one number typed into the menu.
A wireless cyclocomputer does the same wheel math but moves the fork sensor off the cable. The spoke magnet still passes the sensor once per revolution, the wheel-size entry is still 2110 mm, and the only extra step is aligning the magnet gap so the sensor triggers cleanly at speed.
A GPS head unit fixes position instead of counting spokes. It records rides as FIT files, a compact data format created by Dynastream Innovations and now maintained by Garmin, and current units advertise roughly 12 to 20 hours of recording per battery charge. Wheel circumference becomes irrelevant because speed comes from position.
On narrow screens, swipe or scroll the plate sideways.
Sensor radio separates the classes further. Classic units use a reed switch; modern units pair ANT+, a low-power wireless sensor protocol developed by Dynastream Innovations and acquired by Garmin in 2006, or Bluetooth, to add cadence, heart rate and power.
Cadence from a paired crank sensor shows a working band of roughly 60–100 rpm, with a steady club rider holding 80–90 rpm. Heart-rate straps report 120–180 bpm, sitting near 120–150 bpm on moderate terrain. Power meters report 100–250 W sustained.
Setup effort grows with the sensor count: mount, confirm the wheel size on magnet units, then pair each ANT+ sensor one at a time and watch its live reading before moving on.
Further reading