Garmin Edge 840 vs Hammerhead Karoo 2: Which Is The Better Bike Computer For You?

In this post, my comparison of the Garmin Edge 840 and the Hammerhead Karoo 2.

I bought both with my own cash money, the Edge 840 in April 2023 and the Karoo 2 in September 2021 – although it only left the box in August 2022. Hashtag too many devices in the Sportive Cyclist GPS Stud.

I paid £359 for the Karoo 2 (the price on the Hammerhead website) but at least in the UK, you can pick one up for more like £200.

The Edge 840 (Solar version) cost me £520. You do see some discounts that bring it into the mid-£400 range. It’s still a fair chunka-difference in price versus the Karoo 2.

With that contextual intercourse out of the way, let’s compare the two devices. Is the extra cost of the Edge 840 worth it?

What Sort of Riders Would The Edge 840 and Karoo 2 Suit?

Erm, the same ones?

The marketing trumpet, whence converted into plain English, is similar for each device: they’re targeted at the enthusiast end of the cyclist spectrum.

Edge 840 ClimbPro on handlebars


Both devices have sophisticated features. Both appear well made (I’ve dropped them both a few times) using premium materials.

Touchscreens, and the silicon elephant power required to drive them, are not cheap (said the amateur reviewer with no idea what he’s talking about), so both are set at premium price points (the 840 being a more premium price point).

In summary, with these two bike computers, Garmin and Hammerhead are going after the same lycra-clad gentlefolk.

Hammerhead Karoo 2 screen

(Other clothing materials are available. I don’t recommend them.)

But you’ve come here for a comparison, so let’s … comparison.

I’ve divided the list into those factors you should care about and those that, in my low-FTP opinion, don’t really matter. We’ll start quickly with the less important (unimportant… nonportant?) ones.

Size and Weight

Both the Karoo 2 and Edge 840, er, have these characteristics.

Edge 840 solar

The Karoo 2 weighs a bit more, but it’s 50g. Which (lads… Ay. Lads) really isn’t very much.

Hammerhead Karoo 2 device

Let’s talk about you honing that one-pack gut down by a smudgeon. After that you can let weight be a factor in your bike computer decisioning.

I have spoken.

Meanwhile, on a similar ragga tip…


Life would be boring if we all looked the same.

Well, amazing if we all resembled Hercule Poirot, but otherwise… boring.

Edge 840 ride summary

Lucky then that the Karoo 2 and Edge 840 pump out differing visual vibes.

I’ll let the photos do most of the talking. The Edge is more utilitarian. The buttons are more obvious. Shall we call it ‘outdoorsy’?

The Karoo 2 is sleeker with rounded bevels and a focus on the larger screen. Like a smooth, slightly distorted walkie talkie. Which probably does it a disservice.

Looks shouldn’t really drive the decision, even if, in the cycling realm, they often do. To my eyes at least, both look … er, fine?

The Mount On The Karoo 2 Is A Bit… Esoteric

The Garmin mount design has been around a long time. It ticks boxes for both ‘tried’ and ‘tested’. Drop your Edge 840 (or other device of choice) in from the top, quarter turn and it’s locked into place.

Edge 840 mount cleat with contacts


Competitors have largely copied the Garmin approach, either in a way that is somewhat compatible with a fair to middling chance your device will emergency eject at the slightest turbulence, or based on the same principle but rotated by 90 degrees.

Karoo 2 mount cleat

Hammerhead has thrown that all in the bin and gone with a proprietary design. Attaching it is fine. Slide the cleat down the mount and it clicks securely into place. It’s solid on a ride as well. Firm. It’s not going anywhere. A trait that it carries into the detaching process.

Karoo 2 removing from mount

(Bluntly) I’ve found it a bugger to remove at times. An unsatisfactory twist to the side and a shimmy forward. Maybe I’ve got the technique wrong.

Probably not a super helpful factor in shaping your buying decision, but I’ve written this section now. It would appear you’ve read it.


Now on to the more important factors, ‘pon which I do think you should base your purchase decision.

The Karoo 2 Display Is Beautiful (The Edge 840 Screen Is Just Ok)

Whilst size is important, said the grumblemag publisher, the biggest difference in screen terms between the Edge 840 and the Karoo 2 is that latter has a glorious one and the former is just ok.

The Karoo 2 is super clear, contrasty (not a word) and colourful. It has a matte finish, so no annoying reflections in bright conditions thenkyouverymuch.

The Edge 840 is pretty much none of those things. Compared to the Karoo, text is less defined. Although better than previous Edge generations, text sizes stay small, even when you reduce the number of data fields.

Edge 840 data screen

The display on the 840 is a bit washed out compared to the Karoo 2. I think this is more pronounced on the solar recharging version of the 840 that I bought, but also a characteristic of the non-solar version.

Size-wize, the Karoo 2 display is 3.2″ with a 480 x 800 resolution. The Edge 840 is 2.6″ with 246 x 322 pixelanus (latin for pixels).

Hammerhead Karoo 2 review

So the Karoo is objectively larger with higher definition, which is good in that you can show more stuff in more detail.

Or the same stuff but bigger.

(Incisive tech analysis. You’re welcome.)

Side by side, the choice is clear. The Karoo wins, sensors hands down. But in use, on its own, I don’t find myself lamenting the 840’s screen. It’s perfectly usable. It doesn’t detract from the overall experience using it.

And it’s clearly a conscious choice from Garmin not to compete on screen beauty. There are other considerations, and one of them is…

The Edge 840 Has A Much Longer Battery Life Than the Karoo 2

In many of my reviews, battery life goes in the not interesting column. Not in this case.

It’s hardly Michael Lewis level on the interesting-o-meter, but there is at least a significant difference between the Karoo 2 and the Edge 840.

The battery life on the Karoo 2 is a modest (if not stingy) 8 hours, in normal use. The Edge 840 should get well into the mid-20 hours (according to Garmin), with more if you go for the solar re-charging version. This difference will primarily be driven by powering that beautiful Karoo 2 screen (or not, in the 840’s case).

Edge 840 solar charging

The 840 will deal comfortably with a number of long all-day rides and still have juice to spare. I’m unlikely to do an 8 hour ride any time soon, but the 100 milers I’ve done have taken 6 or so hours.


With the Karoo 2, I’d have to use up some brain credits, checking to see if I needed to switch to battery saving mode. Provided the battery is at least half full, with the 840 I really don’t need to think about it at all on any give ride.

On the charging front, Garmin has caught up with the rest of the world by providing a USB-C port on the Edge 840. The Karoo 2 has the same. So both charge quickly. Which is nice.

Edge 840 usb-c port

Both devices are well-endowed from a navigation perspective. Create routes, follow routes, scroll around map screens. All pretty similar.

The maps on the Karoo 2 are more beautiful, rendered as they are on the Hammerhead’s glorious screen. But the Edge 840’s are more than adequate. In scroll-about mode, usability on the Karoo is marginally better by dint of the larger screen. If you’re an Edge user that frequently map-scrolls, you should consider the larger 1040 or 1030 Plus.

Karoo2 map screen

In terms of route calculation speed, the Edge 840 is possibly marginally quicker, though I suspect that the user doesn’t see what goes on the background so can’t assess when the entire route has been calculated. Whatever, it doesn’t make much of a difference when using the Edge 840 and Karoo 2 in anger (and in ecstasy).

The Edge 840 *does* have a Course Demands feature though, where it analyses, for a given route, which of your cycling abilities (let’s assume you have some) will be required. It gives an interesting perspective, albeit most people have an innate sense of how they will find a route based on the question, “How much climbing is there…?”.

Edge 840 Course Demands

There has always been a lot of user noise around re-routing on the Karoo 2, on the Hammerhead user forums and elsewhere. A particular pain point is that navigation can’t be paused – to divert to a cafe just off route, say – without the Karoo 2 invoking a re-route.

For my part, I’ve not found this a particular pain. A lot of my riding is on familiar local routes. Also I am not a DEVIANT (of routes).

Live re-routing is a complex topic in cycling – programmable rules are clearer in A-to-B vehicle navigation. I’m sure, if we dig enough, there’ll be user forums complaining about the Garmin algorithm. But I think I’m right in saying that you can set how the Edge 840 responds to you going off-route, including pausing navigation. So there’s that.

User Interface

The user interface on the Karoo 2 is more intuitive than that of the Edge 840. It’s built on the Android platform, so feels somewhat smartphone-y. It makes good use of the touchscreen, and features and menus are well laid out. The high definition screen allows for helpful hints to be displayed within most features.

Karoo 2 menu screen

Said features, such as the Strava Segments integration or Climber (more on that in a second) make full use of the glorious technicolours the Karoo provides. When you’re blowing out of your Harris whilst the Strava timer ticks down, at least you can marvel in the delicious shade of orange daubed across the screen.

The Edge 840 employs a more recognisably bike computer style user interface. Edge users of old (and probably any other bike computer) will feel at home. That said, the 840 user experience has improved over older generation devices.

More features are directly accessible from widgets that can be added to the home screen (which in themselves display helpful information). There are fewer menus nested within menus nested within menus.

Edge 840 next to 830
Edge 840 (updated UI) on the left

The 840 is stuffed with features, more than the Karoo, so it’s never going to get away from scrolling menus entirely but I do feel Garmin has made a step-change improvement in pruning and simplifying them.

Finally, with the 840, the integration with Garmin Connect has been beefed up. You can now adjust all the settings on the 840 directly from the phone app, including adding metrics and changing the layout of your data screens. This surpasses the Wahoo ELEMNT BOLT/ROAM approach, which has full phone integration but more limited control on the device itself.

Phone integration is less a factor with the Karoo 2. With it being Android based, the device itself acts as a the phone (you can insert a SIM card to give an always-on connection, in addition to the wifi link), so why hook up another one?

That said, Hammerhead does allow you to connect to your actual phone, in order to mirror phone notifications and the like. There’s no partner app because (come on sheeple!) because the app is the phone is the phone is the app. Capiche?

Touchscreen And Buttons

Both devices have a touchscreen.

I’m not the ideal touchscreen tester. I have ‘good fingers’ (a fact I disclose on my LinkedIn profile).

Touchscreens generally work ok for me. I don’t tend to see the lack of responsiveness sometimes experienced by others.

Karoo 2 maps

In terms of said touchscreen, both the 840 and Karoo 2 are… alright.

They’re never going to be ‘modern smartphone great’ – they have to deal with outdoor use and lower power consumption – but they both do a job. They’re both generally okay in the wet, but with the (expected) odd brainfart.

Unlike prior generations of the Edge 8 series (as few call it), the 840 has a full complement of physical buttons. As a result, any and all actions on the 840 can be performed using the touchscreen only, or the buttons only (or a combo). You’re no longer a hostage to fortune if inclement weather renders the touchscreen ‘a bit wazzy’. Or if you want to keep your gloves on.

Edge 840 cycling ability

The Karoo 2 also has buttons. These can control the primary features of the device: navigating between data screens, accessing and moving through menus, starting and stopping the device. There’s a longer list of functions (long press of button A for … zooming out on map screen, fr’instance) but you’ll need to spend the time to learn them.

For choice, the Edge 840 has the most ‘input method flexibility’ (unlikely to be a term) but there’s not a great deal in it.

Climbing-Specific Features

As we shift into looking at specific software features on the devices, this is perhaps a weird one to lead with.

But then, on a new route, knowing about upcoming climbs and whether I have the fitness chops to endure them is key to my enjoyment of a ride.

The good news is that both devices have one of these newfangled climb specific screens. Garmin has ClimbPro whilst Hammerhead’s version is called ‘Climber’. And I like both of them.

ClimbPro is the OG in this space. The new version that Garmin deployed with the x40 generation of bike computers is fandabidozee.

Edge 840 ClimbPro

The gradient charts have more colour variants depicting different percentages of pain, so they look more pro. Where previous versions relied on you following a course for the ClimbPro details to be displayed, the 840 edition pops up whether you’re on a route or not. You can now search for climbs nearby and ascents are highlighted on the map screen as you squizzle around.

But wait right there. The Karoo 2 is just as good, at least in terms of features. Hammerhead was first to introduce a Climb feature than popped up in realtime (i.e. not requiring a pre-loaded route) – so the Karoo 2 is predictive as well.

Karoo 2 Climber

The Karoo 2 makes use of its tip top display to present very attractive gradient charts, with an overall view of the climb and a grid showing gradient over the next few 100m sections. The Climber screen is almost so beautiful you lose track of the pain in your lungs-und-legs. With ‘almost’ doing a big job of work in that last sentence.

The key requirement for a predictive climbing feature is the ability to realise you’re on a climb, which climb you’ll stay on if there are turnings, and that the gradient data is accurate. ClimbPro data is supposedly better. The Karoo 2 has shown me the odd random phantom 20%er which turned out not to be there. If it’s going to be wrong, better that way round.

Edge 840 and 1040 ClimbPro
The Edge 840 is the bottom device (the other one is the Edge 1040)

ClimbPro relies on detailed climb data built into its map files – hence why they are now so large on the 840 (and why this ClimbPro version isn’t coming to the Edge 830). The charts and gradient numbers it tells me generally correlate with how ‘little bit sicky in my mouth’ I feel.

I actually really like both Climber on the Karoo 2 and ClimbPro on the 840. ClimbPro may be more accurate but the Karoo 2 version meets my requirement. I feel a lot happier knowing what legbusters lie ahead of me, and the Karoo 2 is definitely good enough to do that. And the screen looks pretty: an iron gradient chart in a velvet display. Or something.

Training Features

Bluntly, the Edge 840 has a lot more of them.

That’s not to say the Karoo 2 can’t be used to support your sophisticated (or unsophisticated) training programme.

The Karoo can connect to all the usual training aids: heart rate strap, power meter, automated jockstrap. You can create and follow workouts (workout creation via the website or integration with TrainingPeaks). The Karoo can control your smart indoor trainer. It just doesn’t have all the in-built software whizzbangs possess-ed of the Edge 840.

Karoo 2 ride screen

These Edge 840 features include those to help create a training plan and focus it on your ‘A’ event in the future, to identify what abilities you have as a rider (surely there are some) and help you develop them, and those to support you whilst riding, either by reminding you to eat or to maintain certain power outputs over the course of the ride.

If your training is centred on a third-party platform (like the aforementioned TrainingPeaks), then the differences between the Edge 840 and Karoo 2 will be less material.

Edge 840 cycling ability

Similarly, if you’re like me and feel slightly embarrassed describing your velo-nanigans as ‘training’, the Karoo 2 will probably do the job.

That said, I do enjoy seeing the sophisticated (but disappointing) training stats displayed at the end of each ride. There’s a masochistic thrill seeing an electronic device disparage my cycling abilities on a regular basis.

So I prefer the Edge 840 because, you know, more is more. I do accept it’s wasted on me though.

Mountain Biking Features

The Edge 840 has some dedicated mountain biking features, including recording MTB-specific data (e.g. ‘flow’ and ‘hang time’), a dirty map theme (which I’m sure they call it) and Trailforks integration.

The Karoo 2 fits in the bucket of ‘can be used for mountain biking but doesn’t have dedicated features’ (you know, that bucket).

But given I’m primarily a road cyclist that has only just got round to buying a gravel bike, I’m not that bothered about the mountain bike side right now.

Wrap Up

To be fair, I like both the Edge 840 and Hammerhead Karoo 2.

The Edge 840 is bang up to date and probably the best Garmin available right now (though I prefer the larger-screened 1040).

The Karoo 2, whilst it has an attractive user interface, presented on a beautiful screen, is probably not too far off a hardware upgrade. Hence why we’re seeing more discounted offers (I’d imagine).

So, if you’re on a budget, and being in the Garmin training feature ecosystem isn’t important to you, then the Karoo 2 is a good option. Make sure you do buy it on offer though. The £360 list price is toppy.

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Monty - Sportive Cyclist
Monty is an enthusiastic road cyclist with only moderate talent. He started Sportive Cyclist in 2013 to record the journey to his first 100 mile ride, the RideLondon 100. Over time the blog has expanded to include training advice, gear reviews and road cycling tales, all from the perspective of a not-very-fit MAMIL. Since you're here, Monty would also like you to check out his YouTube channel. Also, Monty really needs to stop referring to himself in the third person.

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