Garmin Edge 840 Review: Great Internals in an Outdated Design

CyclistsHub is supported by its readers. We may receive a commission if you buy products using our links.

Garmin introduced Edge 840 a few weeks ago. Thanks to Pulsmetry.cz, I could test it for the past few weeks.

I’ve been using it for the last few weeks (also in Italian Dolomites) to find out what’s new compared to the Edge 830 and what you can expect. I also compare it to competitors’ bike computers.

My Edge 840 rating at a glance:
Battery Life 5/5 | Ease of Setup 5/5 | Display 4/5 | Ease of Use 4/5 | GPS Accuracy 5/5 | Maps & Navigation 5/5 | Price 2/5 | OVERALL 4.3/5
More about this bike computer scoring.

Garmin Edge 840 Pros & Cons

These are the main pros & cons of Edge 840 I found during its use.

What’s New Compared to the Edge 830?

The major changes include the addition of control buttons, increased battery life from 20 to 26 hours, a new user interface (the same we know from the Edge 1040 or Explore 2), Real-Time Stamina, Power Guide, an improved ClimbPro, and more.

I enjoyed the Garmin Edge 830, even though its user interface was clunky. I predicted that Garmin would implement the same user interface found in the Edge 1040 and Explore 2 to the 540s and 840s, along with a few other features.

It’s more user-friendly and easier to use. But it’s still not perfect.

However, I (and many others) didn’t expect to get control buttons alongside the touchscreen. This is a significant improvement and a reason to prefer the 840 over the 540.

If you’re interested, you can learn more about the differences between Edge 830 and 840.

Unboxing & Setup

So, let’s dive right into the setup.

Garmin simplified the initial setup. Now you just scan a QR code like on Wahoo ELEMNT bike computers.

Additionally, if you are already in Garmin’s ecosystem, your previous settings will be loaded onto the new device.

One of the new features I appreciate is the possibility of setting the head unit via the Garmin Connect app.

Due to the button-based user interface, it’s easier and faster to set the data fields via the smartphone app. But you can still use the bike computer itself.

This is one of the differences between Garmin and Wahoo. ELEMNT bike computers cannot be set up directly on the device. This makes them smartphone-dependent.

My Experience

Let’s now talk about individual features in more detail.

Display

The display size of the Garmin Edge 840 is the same as the Edge 830 and 540, at 2.6 inches, with a resolution of 246×322px.

It’s still a touchscreen, and I find its size ideal for most people. It makes the head unit compact, relatively lightweight, and suitable for daily riding.

However, the Edge 840 now also has control buttons. But we’ll talk more about this later.

The Edge 840 has good readability and brightness, making it easy to read even in direct sunlight. However, its finish is glossier than that of Wahoo computers, which means it reflects more glares. But I still could read it easily in most scenarios.

Thankfully, unlike the Hammerhead Karoo 2, it has an ambient sensor that adjusts the brightness based on the outside light conditions. So it spares the battery.

The 840 can fit up to 10 data fields on one data page, which is the same as the Edge 540. However, it doesn’t allow you to zoom in and out like ELEMNT computers to make the data fields larger or smaller. Instead, you have to change the entire data screen layout.

Thanks to the touchscreen display, adjusting data fields is much easier on the Edge 840 than on the 540. However, the customizability via Garmin Connect minimizes that difference. I’ll talk more about this in the Control section.

One thing that disappointed me about the new Garmin Edges is the wide bezels. In 2023, I would expect efforts to maximize the display size while keeping the device’s dimensions (a trend we can see on smartphones).

Battery Life

The claimed battery life of Edge 540 is 26 hours (same as Edge 840), which is a 30% increase.

The Solar version can extend the battery life by up to 25 minutes per hour of riding in ideal conditions. This means up to 32 hours in total. For comparison, Edge 1040 has a claimed battery life of up to 35 hours.

Remember, the solar panel can’t recharge the device. It only extends its battery life.

I was able to get around 24.25 hours during my testing. I had my HR monitor, power meter, Varia RTL515, and phone connected to the bike computer.

This battery life pleasantly surprised me because it almost meets the claimed battery life. From my experience, Garmin bike computers lagged behind it.

On the other hand, they have the battery-saver mode, so you can squeeze more of the remaining battery (unlike on ELEMNT bike computers).

Another change is that Garmin switched from a MicroUSB to a USB-C charging port. This is not a surprise but rather an obligation in 2023.

Control & User Friendliness

One of the biggest changes from the 830 to the 840 is the inclusion of control buttons, which are the same as those on the 540. This means you can control the 840 with either touches or buttons.

Thanks to the new user interface, controlling the device is a bit easier than Edge 830. You can also set the data fields and other settings using the Garmin Connect app.

Honestly, I wouldn’t mind if the Edge 840 was not customizable via smartphone because you can quickly find and set up everything on it. However, this doesn’t apply to the button-based 540.

So, how reliable is the touchscreen display when you sweat a lot, it’s raining, or you’re wearing gloves? It works surprisingly well (although you may have to repeat your input sometimes, it’s mostly fine). Check out the following video for an illustration.

In case you ride MTB, wear gloves, or have frozen fingers, you can use the control buttons. I believe this is the step in the right direction – maybe Garmin inspired itself with Karoo 2, which also has a touchscreen display and control buttons.

Maps & Navigation

Edge 840 features full on-device navigation and adds one technology that greatly improves its accuracy – Multi-band GNSS. But more about it later.

The 840 comes with preloaded maps for your region, and you can also download other regions.

The increased storage of 32 GB will allow you to download almost the entire world. Unfortunately, there is no way to download the maps wirelessly, and you must use the Garmin Connect desktop app.

Garmin also improved the navigation experience. For example, the head unit is much faster when calculating routes than its predecessor.

You don’t have to wait about a minute for the route to load. Now, it loads almost instantaneously. Thumbs up!

Additionally, there are multiple ways you can use navigation. Edge 840 can navigate you to Points of Interest (POIs), a selected point on a map, back home, a preloaded route, etc. Unlike 540, it also features address search and on-device course creation.

Accuracy

The 840 supports GPS, GLONASS, Galileo, and newly Multi-band GNSS satellite systems. The Multi-band GNSS improves the accuracy, especially in areas with worse signals.

I tested 840’s accuracy on my favorite segment in the forest, where I test all bike computers. Unsurprisingly, its accuracy is comparable with the Edge 1040.

I have also used the 840 in Italian Dolomites in the highest accuracy mode. I noticed the accuracy was not that high, and sometimes the route even completely missed the real route. You can see one of these routes here.

ClimbPro

ClimbPro is a popular feature that displays details about climbs. The earlier version only worked for planned routes.

However, on the new Garmin Edge devices, it also works for unplanned routes (just like Hammerhead’s Climber). I tested this feature, and it’s not 100% accurate yet.

Sometimes, it starts displaying the climb too early or too late. Additionally, sometimes, the percentage gradient displayed is not correct. I assume that the accuracy will improve with future firmware updates.

What bothers me is the limited editing of data fields. Two-thirds of the screen is taken up by the map and gradient. For example, I would personally prefer to replace the map with other metrics. See the following picture for illustration and comparison with other ClimbPro-like features.

By the way, I will be publishing an article comparing all three of these features soon.

Real-Time Stamina

Real-Time Stamina and Power Guide are functionalities first introduced on the Garmin Fenix 7 watch and later implemented into the Garmin Edge 1040 and 1040 Solar.

Real-Time Stamina is a feature that provides accurate energy and recovery guidance during activities, while Power Guide provides real-time training targets and alerts to help optimize performance.

Honestly, I didn’t find them very appealing when testing the Edge 1040, although I understand their usefulness for a certain group of riders.

Especially for Real-Time Stamina, it’s important to have collected riding data so that the algorithm can “get to know you” and provide accurate recommendations.

You’ll achieve the best accuracy, particularly when you use Garmin watches with the same functionality. These watches can track your data throughout the entire day/night, not just during bike rides.

Since I have mainly used non-Garmin bike computers in the past, I haven’t collected that much data yet.

However, in the Dolomites, I turned on Real-Time Stamina on some routes for fun.

Logically, it showed a shorter estimated distance when riding at the limit than when riding at a more relaxed pace.

It was also interesting to watch the decrease in so-called potential. I never completely exhausted it, but its value also decreased as fatigue increased. Its lowest value was around 12 %, and I remember being tired.

Someday, I’ll try pushing it down to 0 and see if that means I can no longer pedal.

Power Guide

Power Guide is a feature that is perhaps even slightly more useful than Real-Time Stamina. It just doesn’t look like it at first glance.

The way it works is that you choose the route you want to create a Power Guide for. You then specify a few more details, such as the total weight of your bike and accessories, riding position, etc., and most importantly, the intensity of your ride.

The algorithm will then suggest target watts adapted to the route profile. As a rule, the intervals are higher on hills while lower on descents or flats.

This function is suitable for those who don’t want to follow the watt zones of structured workouts strictly but want at least some structure.

It can also help those who have favorite routes and want to improve their time on them.

By design, however, this feature is more suited to riding solo than in a group.

Extras

Garmin crushes its competitors (mainly Wahoo) with these features, but it comes at a cost. From my experience, Wahoo ELEMNT bike computers are more user-friendly and easier to use.

Connectivity

Garmin Edge 840 has ANT+, Bluetooth, and WiFi connectivity. 

You can pair it with additional sensors like HR monitors, power meters, cadence and speed sensors, cycling radars, etc.

Of course, Edge 840 can automatically upload your activities to 3rd party apps like Strava or TrainingPeaks or control your smart trainer.

Despite Bluetooth and WiFi, you still have to download maps to it via the Garmin Express desktop app. This is one of the biggest disadvantages of the Edge 840.

Hopefully, Garmin will include this functionality with future software updates to match Wahoo computers.

Garmin Edge 840 Alternatives

Garmin Edge 840 Technical Specifications

Here is the summary of the main features and the technical specifications of the Garmin Edge 840.

My Verdict

I enjoyed using Edge 840 because of its buttons + touchscreen display combo. It’s by no means a cheap bike computer, but I believe it has the potential to become quite popular.

It’s packed with many features from the higher-end units (Real-Time Stamina, Power Guide, ClimbPro) and offers above-average battery life.

You can skip the 840 Solar, as it doesn’t make much sense financially (1040 non-solar for just $50 more seems like a better deal).

On the other hand, I am somewhat disappointed with the design. The 840 would have deserved narrower bezels.

What are your thoughts? Let me know in the comments.

Anyway, I hope you find this review helpful. If you are considering the purchase of the 840, please use the links below to support Cyclists Hub.

Recommended Accessories

Below, I include a few accessories worth using with the Garmin Edge 840.

Garmin Varia RTL515 Radar

Garmin Varia RCT715 Radar with Camera

Garmin Edge 840 FAQ