Garmin Edge 840 review: a do-it-all bike computer

The Garmin Edge 840 is a GPS bike computer for riders who want proper mapping and serious training data on a compact unit. It arrived alongside the button-only Edge 540 and sits below the larger Edge 1040 in Garmin's range; the headline difference from the 540 is the 2.6in colour touchscreen, which lets you pinch and zoom the map, swipe between pages and tap through menus, while physical buttons still handle start/stop, laps and anything you would rather not do with a cold, wet finger.

That combination is the whole pitch. Through a British winter you can lock the screen and run the ride from the buttons; on a summer sportive you can zoom into a junction instead of scrolling through a menu to find it.

It is aimed at club riders, sportive entrants, gravel riders exploring new lanes and anyone training with power or heart rate. It is neither the biggest nor the cheapest unit Garmin makes, which is exactly why it suits so many people.

Most bike computers force a choice: buttons that work in the rain or a touchscreen that is quick in the dry. The Edge 840 refuses to pick. The screen can be locked so rain and road spray do not register as taps, and the three buttons under the screen cover start/stop, laps and page changes.

In practice that means the touchscreen is reserved for what it is good at: pinching the map, dragging it around, tapping a data field and scrolling through menus during a coffee stop. Everything time-critical stays on a button.

Data pages are set up on the device or in the Garmin Connect app, with a sensible number of fields per page depending on whether you are racing, navigating or commuting. Profiles keep those setups apart, so your commute screen does not have to look like your interval session.

The 840 ships with routable cycle maps for your region and handles the basics properly: turn-by-turn prompts, a distance-to-next-turn banner, off-course warnings and automatic recalculation if you ignore a turn. Courses sync from Garmin Connect, Komoot or Strava, and GPX files can be imported if you plan elsewhere.

Two features earn their place on British roads. Popularity-based routing leans on the tracks large numbers of Garmin users have ridden, which usually throws up better lane choices than a straight-line algorithm. And ClimbPro breaks the route into climbs, showing what is left of the current one and what is coming, which is far more useful on an unnamed 12% ramp in the Chilterns than a total elevation figure.

Back-to-start navigation and point-to-point routing are there for the days when a group splinters or the café stop moves.

This is where the 840 pulls away from a basic navigator. Stamina estimates how much you have left in the tank, based on your power or heart-rate history, and shows it falling during the ride; used properly it is a reason to ease off at 60km rather than blow up at 90km. Power Guide builds a pacing plan for a course and then tells you whether you are ahead or behind it.

Training Status and load tracking give a running picture of whether you are building or digging a hole, and structured workouts sync from Garmin Connect and third-party platforms so a Tuesday night interval session can run straight off the head unit.

It also plays nicely with the rest of the ecosystem: power meters, heart-rate straps, Di2 and eTap shifting, Varia radar and lights, and smart trainers for indoor sessions.

Garmin rates the standard Edge 840 at up to 26 hours, which is realistic for a long day out with navigation running but will fall if you leave the backlight high, run several sensors and keep the map on screen. The Solar version adds a panel that tops the battery up in daylight and a higher rated runtime, though the gain depends entirely on how much sun you actually ride in.

USB-C charging means one cable for the computer, your phone and your lights, and a small power bank in a jersey pocket covers multi-day trips. Rides upload over Wi-Fi when you get home, with Bluetooth to your phone as the fallback, and smart notifications, LiveTrack and incident detection need a paired handset.

Buy it if you want one computer that covers a Tuesday chaingang, a Sunday club run, a gravel explore and a week in the Alps. The 840 is small enough to leave on the bike, capable enough that you stop thinking about it, and the touchscreen genuinely speeds up route checking and menu work.

Buy it if you race or train to a plan. Stamina, Power Guide and the training load metrics are what you are paying for, and they are the same core tools the flagship uses.

Skip it if you almost always follow a pre-loaded route and rarely touch the map. The button-only Edge 540 covers that job for less money, and the buttons are the part that matters in the rain anyway.

Skip it if screen size is your priority. Riders who need reading glasses for a small map, or who ride mostly off-road with a route line to follow, will be happier with the bigger Edge 1040.

Skip it if you only need basic speed, distance and a breadcrumb trail — that is a much cheaper category of computer.