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Hammerhead Karoo



Not as good as it can be, but already better than anything else for core functionality, with lots more promised

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

What the scores mean

Good scores are more common than bad, because fortunately good products are more common than bad.

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  • Very Good
  • Good
  • Quite good
  • Average
  • Not so good
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  • Bad
  • Appalling

The Hammerhead Karoo is a work in progress, but even with its current functionality it's the best bar-mounted GPS unit I've used. It's powerful, intuitive to use, has a fantastic screen and decent battery life. For a day on the roads or trails, it's hard to beat.

  • Pros: Powerful, easy to use, great screen, excellent routing options, good battery life, constantly getting better
  • Cons: SIM functionality is limited, no hardware beep, bulky

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Build quality: good, with easy-to-use hardware buttons

The Karoo itself is a big old beast, no mistake about that. At 98 x 72 x 28mm it's bigger than any other dedicated GPS computer, and at 168g it's about 50g heavier than other top-end units such as the Garmin Edge 1030. That may be an issue for you; I'm happy mounting my phone to my bar (I have a Garmin mount glued onto the case) so It's not anything new for me to have a big thing to look at. I wouldn't do that on the race bike, but being a race computer isn't the Karoo's primary function.

Hammerhead Karoo - mounted side.jpg

The form factor of the Karoo is squarer than most, with the Gorilla Glass screen taking up the whole of the front and five hardware buttons located on the two sides. There are two raised buttons on each side with a textured finish that are pretty easy to use in gloves, with the power button sitting flush with the body. The Karoo uses a titanium and aluminium chassis, and on the back there's a removable plastic cover, behind which is a SIM card port protected by a rubber bung. On the back there's a standard Garmin quarter-turn mount.

Hammerhead Karoo - back.jpg

Hammerhead has gone with the Garmin mount because it makes a lot of sense: it has the lion's share of the third-party mount market. I don't think the mount is the best though, especially for heavier computers like the Karoo. Overall it just feels a bit flimsy for the weight it's carrying, and the click engagement on the supplied BarFly mount isn't especially positive, so the computer doesn't always sit exactly straight on the mount. It's okay, and I don't have any particular worries about the Karoo falling off, but other systems – Lezyne's eighth-turn mount, for example – give a much better engagement.

Hammerhead Karoo - mount.jpg

Operating system: Android, but very Karoo-specific

The Karoo runs on the Android 6 operating system. If you've used an Android smartphone then there are certain telltale signs – the status bar, for example – that it's an Android back-end, but the firmware has been heavily modified to be specific to this device and it certainly doesn't feel like a phone made to do GPS duties.

Hammerhead Karoo - screen 1.jpg

With a WiFi connection available all updates are over the air, and Hammerhead is working to an update schedule of one new release per fortnight. Some updates are bug fixes and minor UI changes, while some will introduce new features over time. More on that in a bit.

Screen: the new benchmark

The Karoo has the best screen of any bike computer I've ever tried, bar none. There are two reasons for this. Firstly, the resolution – 640x480, at 229 pixels per inch – is a class above anything else bike-specific that's out there. It's not just that, though: the Gorilla Glass top layer of the screen has a semi-matt coating that does a really good job of reducing reflections from the sky and things passing overhead – tree branches, buildings, and so on – meaning that the information is more visible for more of the time. I found that even in bright sunlight I only needed the screen just above half power on the brightness slider; if I have my phone on the bar on a sunny day I really need to dial the brightness all the way up in order to use it, which cuts the battery life considerably.

Hammerhead Karoo - screen 8.jpg

The screen is touchscreen, but it's cleverly also not a touchscreen most of the time. Because the Karoo has hardware buttons you really only want the screen to be touch responsive when you're in the menus, and that's basically how the Karoo works. On the map screen you need the option of turning the screen on to jiggle about with the zoom, and move the map around to see what's coming up, so there's a padlock icon that you press to unlock it.

All this works really well, and it means that when you're out in the rain the screen is never – not so far for me, at least – affected by raindrops hitting it, which is the big problem if you're using a phone; that and your phone getting wet, though many are waterproof these days. You can swipe horizontally between screens, and down from the top at any time to change the brightness or turn connectivity on and off; a swipe is not an action a raindrop can easily replicate, so it's not an issue when it's wet.

Hammerhead Karoo - wet screen.jpg

Routing: some issues but generally works very well

My first outing with the Karoo was a 100km loop over the Mendips. I was out for about five hours in total including a coffee in Cheddar. I created the route on the Karoo itself through the routing app. Creating a route can be as simple as saying where you want to go (search for a place, or drop a pin on the map) and asking the unit to find the way. You can drop multiple pins, so it's possible to do circular routes too. I initially found that after about four or five points the app on the Karoo itself tended to get pretty laggy and it crashed from time to time, but the mapping engine has been reworked in subsequent firmware updates.

The Karoo has a pretty broad understanding of what a road might be. For example, this is a road...

Hammerhead Karoo - forest track.jpg was the muddy farm track that preceded it. Not a problem on my Kinesis Tripster ATR with 40mm tyres – ideal, in fact, since I didn't even know this route existed and it was lots of fun – but I'd have been grumbling if I'd been out on my road bike, so caution is advised if you're planning a ride somewhere you're not familiar with.

The desktop/mobile app (more on that below) allows you to choose between road, gravel and mountain bike routing, with increasingly off-road-biased routes the more knobbly you go. That option should be coming to the Karoo app in due course.

The route I created on the Karoo had turn-by-turn instructions, which display on the bottom of the screen; you can turn them off if you prefer. There's no hardware for sound, so the Karoo doesn't beep to notify you of directions. That's fine for me – it's the first thing I turn off, generally – but it might be an issue if you like a beep to warn you. Upcoming software updates will add bluetooth support for headphones, so audible notifications will be available through those, as will streaming services such as spotify further down the line if listening to music on a ride is your thing. It's a workaround rather than a fix, so if beeps are your thing this probably isn't the GPS for you. At the moment, anyway; probably the next hardware round will include an audio capability of some sort.

Hammerhead Karoo - routing on device.jpg

If you turn the screen off, the Karoo won't turn itself back on to warn you of an upcoming or missed turn. That would be a good addition to the functionality, especially on long rides where you want to keep the screen use to a minimum. Hammerhead says it's looking into that. Turn by turn instructions are generally good; the only one that isn't is roundabouts, where the Karoo just warns you there's a roundabout coming rather than telling you which exit to take. That's okay on the map screen where you can see where you're going, and less so on the data screens.

Hammerhead Karoo - routing.jpg

Head off route and the Karoo will try to reroute you. Again, pretty much anything seems to be fair game as far as the unit is concerned – farm tracks, footpaths, someone's driveway that wasn't obviously a right of way – and one time it got confused and tried to route me back down the route the wrong way to pick it back up at a point it decided I needed to pass.

Fair play though: when I didn't do that but instead just picked up the route, it soon realised and started giving me the correct instructions again. If you've gone off route, or your route isn't appropriate (I encountered one closed road, and also there was the muddy bit I'd have worked around on a road bike) then the best thing to do is zoom out the map and find a way back to the red line a bit further along.

Hammerhead Karoo - rerouting fail.jpg

When I got to Cheddar I decided to reroute myself back up the gorge and down Burrington Combe, as opposed to following the route I'd planned. Since the cafe had Wifi I hopped on my phone and planned the route on the Hammerhead dashboard, instead of using the app on the Karoo itself. The routing app on the dashboard is excellent: really quick and easy to use. You can drag your intermediate points around and the route will be recalculated. Once you save it, the route will be automatically synced to the Karoo if that's also on the Wifi, and you can switch routes mid-ride without stopping and starting again. It's all so simple that it makes you wonder how you've been managing up until this point.

The route I'd created on the phone didn't have turn-by-turn instructions – I'm not sure why, probably because I didn't leave enough time for the system to generate them – so I just followed the wiggly red line back to the finish. That's my preferred method of navigation, to be honest. Your mileage may vary there. Subsequently I've found that every route I've followed – either created on the Hammerhead, or imported from Strava – has had turn-by-turn options available, even if I didn't use them.

One word on the maps: they use the desktop colour palette which is reasonably low contrast, and not ideal for reading on the bike. They'd be much easier to read on the go if the contrast between the roads and the backgrounds was increased a bit; that would mean you'd be able to run the screen at a lower brightness, which would improve battery life.

You can configure as many data screens as you want, to give you all the metrics you could ever need. There's all the usual stuff – speed, sensor readings, altitude, route-following and so on – but also some graphical data such as an elevation plot of your ride, and a colourful bar to show you your heart rate or power zone in a more graphical way. More stuff like that will be coming, including the ability to show an elevation plot of a route you're following, and your position on it. That will certainly be handy.

Hammerhead Karoo - page sets.jpg

Normally, playing about with data screens is a faff, and often you're better off doing the configuration from the smartphone app that pairs with the computer. But since the Karoo behaves pretty much exactly like a smartphone in menu mode, there's no need for that. In fact the Karoo doesn't have a partner app at all: it's designed to be an entirely standalone device, although there's still the desktop portal that's the route for some functions such as importing routes.

At the moment the layout of the screens doesn't make the best use of of the screen real estate that's available: the metrics basically sit one under the other, and as the number of metrics increases the type gets increasingly small, with space either side. Again, future releases of the firmware will offer more layout options.

Connectivity: comprehensive but SIM is under-utilised

Pairing sensors seems to work well. I connected up a pair of Garmin Vector 3 pedals on ANT+ and a Lezyne HR strap on Bluetooth with no issues. The Karoo lost the heart rate data after my mid-ride stop and I thought it was maybe the battery in the strap itself, but turning Bluetooth off and back on again fixed the connection. I didn't have any dropout issues when I was actually riding.

Hammerhead Karoo - sensors.jpg

The Karoo has a SIM card slot, which you access by pulling the back cover off (or dropping the unit on the stone floor of the cafe – not recommended, though it survived fine) and removing a rubber bung. If you stick a SIM in there then you're not reliant on a Wifi connection to sync routes with your Hammerhead dashboard, or upload rides and sync to Strava or another platform.

At the moment, that's about it: the Karoo doesn't have a microphone or a speaker so you're not ever going to be making emergency calls, and though it has a three-axis accelerometer that could in theory detect a crash and notify an emergency contact via SMS, it doesn't do that as of yet.

One thing the Karoo will be doing, though, is live tracking: broadcasting your real-time location to a contact so that if you end up in a ditch someone will know where you are. That functionality isn't in the firmware yet but it is coming, probably at the start of 2019. That'll definitely be a useful addition to the unit and a reason to fit a SIM. Currently I wouldn't say it's worth the bother.

There's a lot of stuff in development. Hammerhead is pretty open about the things that are coming to the Karoo, and there's a roadmap page which sets out the priorities for the upcoming features. That page is all software updates, and some – Strava live segments, upcoming elevation on routes, support for Garmin's Varia lights, smart trainer support for workouts – will definitely add to the appeal of the Karoo.

Hammerhead Karoo - Strava.jpg


As mentioned before, the Hammerhead team updates the firmware of the Karoo every two weeks. Updates happen over Wifi, and you can remember as many Wifi networks as you like, like you would with an Android phone. The Karoo uses Wifi to sync activities at the end of your ride, with uploads to Strava more or less instantaneous.

Sometimes updates give you access to stuff that doesn't make a lot of sense on its own – for example, my Karoo now has Bluetooth connectivity for a headset but no functions that play audio – but they're part of a longer game. Audio turn-by-turn and workout notifications are two things that will be coming in the future, along with music streaming. Maybe you wouldn't want that for your outdoor ride, but you might well do if you were smashing out an indoor workout with the Karoo controlling your trainer; that's another function in development.

Hammerhead Karoo - downloading update.jpg

In theory the Karoo could do most things that an Android phone could do, and all the things most other GPS computers can do, and more. It doesn't do all of them yet but the pace of development is pretty quick, so actually reviewing it is kind of like trying to hit a moving target. As of now, the core functionality is good, but the offering has improved over the time I've been testing the Karoo and looks likely to continue doing so.

Battery: plenty for a day of riding

Battery life is pretty good, considering the size of the screen. Hammerhead claims up to a 15-hour run-time, but like all battery claims that's very much an absolute-best-case scenario. At the end of my 5-hour Cheddar ride the battery was showing 55% remaining, so there was plenty left in the tank, but not enough to do 15 hours. It was a pretty murky day so I didn't need the screen to be especially bright, and on bits of the route I knew well I turned the screen off to save the battery.

On subsequent rides I found that having the screen on all the time didn't actually affect the battery life that much; in most scenarios the Karoo was giving me about an hour of operation for 10% battery drain when riding, and the battery doesn't deplete very quickly at all when it's paused and you've turned the screen off in the cafe. Rides of up to about 9-10 hours should be fine; on occasion I managed some way above that.

Beyond that you're going to need to think about your charging strategy. The Micro-USB charge port is IP67 waterproof and you can charge the Karoo while you're riding, provided that you can fit the charge cable between the unit and the handlebar as it's on the back. With the supplied Barfly mount, I couldn't get a standard Micro-USB in there, but a right-angle one fitted okay. It's still not a great idea to charge if it's really wet as the moisture can short the contacts.

Hammerhead Karoo - USB port.jpg

Overall: really impressive, even if it's a work in progress

No doubt about it: the Karoo feels unfinished. That's not unusual when I get a GPS unit or some other tech trinket to review on, as they're usually first release and not everything works as it should. What is unusual is that Hammerhead is entirely upfront about it, with a roadmap for what's coming and an indication of the priorities.

Everything that has already been implemented works very well, to the point that the Karoo is the easiest computer to use that I've yet tried. The hardware is powerful, the physical unit is well built with useful hardware buttons and the best screen you can get on a GPS. The firmware does everything efficiently and sensibly, with a pleasant interface that's highly configurable.

Hammerhead Karoo - data display.jpg

Even as it stands, it's easy to recommend, and there's plenty more coming. When the Karoo can do live tracking independent of your phone, and take you through your workouts on TrainerRoad while playing you your favourite Spotify playlist through your Bluetooth headphones, it'll be an enticing prospect indeed.

The Karoo hasn't fulfilled its potential yet, and there are some omissions – audio hardware for example – that will limit its appeal, as will its size. So there's no way I could give it full marks as it stands. But what I will say is this: the Karoo is the best all-round GPS computer I've used yet on my bike. It very effectively combines everything I like about using my smartphone – powerful performance and a great screen – with everything I like about using a dedicated GPS – sensor connectivity, all-weather performance and good battery life – with very few downsides. Okay it's a bit bulky, and still very much in development, but it's already ahead of the pack.


Not as good as it can be, but already better than anything else for core functionality, with lots more promised

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Make and model: Hammerhead Karoo

Size tested: 98 x 72 x 28mm

Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Hammerhead says, "Designed by cyclists, Karoo is the next generation of cycling computer. Our goal is to bring the best cycling-specific maps, training tools, and social features to your ride."

Tell us some more about the technical aspects of the product?

Operating System Karoo OS (built on Android 6.0)

Software Updates Regular, over-the-air via WiFi

Physical Dimensions 98 x 72 x 28 mm (3.8" x 2.8" x 1.1")

Weight 168g (5.92 Oz)

Water Rating IP67


Metal-injection molded skeleton with high-impact resistance polycarbonate. Endurance rated buttons with an affirmative mechanical click. All-weather paint finish. Sealed with 8 screws.


3200mAh Lithium-Ion Polymer cell, ~3 hour full recharge, ~10 hour runtime with internet connectivity and all features running, ~15 hour runtime with just screen, GPS & sensors.

Mounting Standard quarter-turn mount interface works with aftermarket brackets

Touchscreen Capacitive with multi-touch, pinch-zoom, and water droplet rejection

Cover glass 1.1mm Corning Gorilla GlassTM


Full device navigation via side buttons (2 on each side for those really muddy rides) and a power button with reset.

Display Technology High resolution, non-reflective, military-grade screen for maximum visibility in all conditions

Display Size 3.5" diagonal (2.10" x 2.80" or 53.28 x 71.04mm)

Display Resolution 640 x 480 - 229 Pixels per inch

Backlight Auto-adjusts to ambient light conditions.

Ports Waterproof Micro USB port and Micro SIM card slot for cellular connectivity

Custom Applications Karoo comes standard with a suite of custom Android-based apps to operate the device.

Recording interval 1-second


Maps & Navigation

Turn by turn navigation Turn by turn navigation on any route created or imported.

Offline Map Updates On-demand, offline downloadable maps, based on Open Street maps.

Routing On-device route-making and navigation via waypoints or location searching.

Route Types Create routes optimized for road, gravel and MTB riding.

Re-routing Reroute in-ride on any route that you make or import

Route Sharing Share any route via the dashboard. Shared routes can be edited by other Karoo users

Route Import

Import, create and manage routes on the Karoo Dashboard: GPX files, Strava, MapmyRide, Ride with GPS, OutdoorActive, Trailforks, MTBProject,, Gpsies

Route syncing

Automatically sync new routes from the Hammerhead Dashboard. Any imported activity can be made into a route with turn-by-turn navigation.

Activities syncing Automatically sync activities to Strava

Offline Maps Cache any region on Karoo, offline map tiles and routing are auto-cached for your planned ride

Fast GPS Lock Satellite lock in under 5 seconds.


Processing and Connectivity

Global Navigation Satellite System (GNSS) GPS, GLONASS and Cellular Triangulation, -163dBm sensitivity

WiFi 2.4 GHz - 802.11 b/g/n


Any cycling specific ANT+ sensors from any manufacturer can connect seamlessly. Connect up to 7 at any time

Cellular Connectivity 3G, 850/900/1900/2100 MHz


Bluetooth Smart (4.0+) with audio streaming (A2DP) Including other Bluetooth profiles for later apps and voice control (HSP - headset profile, HFP - hands-free profile)

Processor Quad-core ARM Cortex-A53 MPCore - 1.3 GHz, optimized for longer operational life


Storage 16 GB with 8.5GB of user space (thousands of miles of routes, a full suite of apps, and all of your data).

Altimeter Barometric, accurate to 0.012m, GPS calibrated

Accelerometer 3-Axis

Compass 3-Axis Magnetometer

Light Ambient light sensor for backlight dimming

Temperature Internal sensor


External Sensors and Devices

ANT+ / Bluetooth 4.0

Capable of logging any number of Bluetooth 4.0 and 7x ANT+ devices simultaneously. Heart rate, Speed, Cadence, Power Meter, Shifting*, Trainer control**, Muscle oxygen***, Other (Future Releases)



Data display Customizable profiles allow you to select what data is displayed while riding

Account Synchronization

You can log in to any Karoo with your Hammerhead account and automatically sync your pre-paired sensors, routes, page sets, Strava account, and more.

Customizable page sets

Karoo allows you to create an unlimited number of riding 'page sets' in the Pages app, which can be customized to display different types of data for different types of riding.

The Karoo Dashboard

Login to the Karoo Dashboard on your computer to more quickly design and alter routes. You can also easily import routes as URLs from a wide variety of services, such as Strava, MapMyRide, Trailforks, and more. All routes on your Dashboard seamlessly and instantly with your Karoo.

Auto Start/Stop/Pause Customizable auto pause.


Future Software


Hammerhead has built Karoo on the most flexible software stack possible. This allows any developer to bring value to our platform. Our goal is to be nimble with software releases and build services that cyclists want. Our customers will be a part of making this paradigm a reality, below are some of the ideas that we are currently designing


Build custom workout profiles with alerts and specific heart rate, power or pace goals, link them to routes, and share them with friends.

Intervals Easily build interval workouts or choose from presets designed by coaches

Strava segments

See strava segments while route-planning. Add segments to your route and race them with real-time feedback.

Live-tracking Live location and sensor data can be shared with anyone through a URL.

Group Tracking Share location, meetup times and courses to friends on your ride.

Weather Display

Get a weather forecast pre-ride, wind data on the route and a head's up for rain. Post-ride wind, power and speed data is correlated to give you a better understanding of your training session.

Training Calendar

A whole new standard for training planning, workouts are preloaded on your bike, if you miss one the plan adjusts. Integrate your indoor and outdoor training data.

Ride leader tools

Visualize the heart-rate and power output of everyone in your ride group. Get instant feedback on the relative strain of your team.

Training groups

Find ride groups and training friends in your city, match with cyclists at your level and make group rides easier.

Live training interface Coaches who tailor your training plan and give you live feedback.

Music Storage and Playback Hammerhead will incorporate 3rd party music apps like Spotify to enable some music capability.

Rate the product for quality of construction:

Good overall. The Garmin mount maybe doesn't feel like the perfect choice for a computer this heavy.

Rate the product for performance:

So easy to use and intuitive. Superb screen. Good battery life.

Rate the product for durability:

It's been dropped a couple of times, a bit of superficial damage but no issues, and five hours in the rain didn't throw up any waterproofing problems.

Rate the product for weight (if applicable)

It's about the heaviest GPS unit I can think of.

Rate the product for comfort (if applicable)
Rate the product for value:

It's expensive but you're getting a lot for your money. I'd buy one, though I might wait for the hardware update next year.

Tell us how the product performed overall when used for its designed purpose

Brilliantly. It's a joy to use.

Tell us what you particularly liked about the product

Powerful, easy to use, great screen, excellent routing options, good battery life, frequent updates means it's constantly getting better.

Tell us what you particularly disliked about the product

Functionality is currently limited, no hardware beep, bulky, Garmin mount maybe not the best for a unit this big.

How does the price compare to that of similar products in the market, including ones recently tested on

It's in the same ballpark as other top-end computers such as the Garmin Edge 1030 and the Xplova X5 Evo. The Garmin is more expensive at RRP (£499) but widely discounted, the X5 is about the same at RRP.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your overall score

The Karoo really is a lovely bit of kit, and it's getting better all the time. At some point it might sneak up to full marks. It's not quite there yet.

Overall rating: 9/10

About the tester

Age: 45  Height: 189cm  Weight: 92kg

I usually ride: whatever I'm testing...  My best bike is: Kinesis Tripster ATR, Merida Scultura

I've been riding for: Over 20 years  I ride: Every day  I would class myself as: Experienced

I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, club rides, sportives, general fitness riding, fixed/singlespeed, mountain biking, Mountain Bike Bog Snorkelling, track

Dave is a founding father of, having previously worked on Cycling Plus and What Mountain Bike magazines back in the day. He also writes about e-bikes for our sister publication ebiketips. He's won three mountain bike bog snorkelling World Championships, and races at the back of the third cats.

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