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27-06-2022 | Frank Jansen

Karoo 2 review

The Karoo 2 by Hammerhead is a head unit that has been on the market for about 2 years now. It's about time we put it to the test. Can the Karoo 2 stand up to direct competitors like the Garmin Edge 1030 and the Wahoo ELEMNT Roam?

Photo: the Karoo in action in a Hide My Bell mount with Garmin fitting. Nice detail: the dark mode. During this ride, the Di2 support was still working.

The hardware

What makes the Karoo 2 different from other bike computers is that it's actually a phone disguised as a bike computer. The device runs on Android, and it can accommodate a SIM card (though that's not mandatory, more on that later). For the nerds among us, it is even possible to side load Android apps, though that is not officially supported. The big advantage of this is that the Karoo has a much better screen. And with that we have immediately mentioned the big plus.

The screen is the best on the market as far as I'm concerned. The brightness and sharpness is fantastic, the colors are vivid and the screen is easy to read, even in full sun. However, there is one catch. Just like a phone, the screen really needs backlight. For me, 50% is the minimum. And that, of course, affects the battery. I didn't get below 10% per hour in my tests. Now I hear you say: I never ride longer than 10 hours. And that is indeed true for 95% of cyclists. But consider that the number of ultra cyclists, bike packers, randonneurs is on the rise. And as gran fondo riders are also sometimes on the bike for more than 10 hours. For them, the Karoo is not an option. Moreover, you must also look at battery life in the context of the competition. And then 10 hours is very, very little. For your information, the Garmin 1030 has 20 hours and the new 1040 35 hours. An ELEMNT Roam will last about 17 hours.

Photo: from left to right: Wahoo ELEMNT Bolt v1, v2, Garmin Edge 830, Hammerhead Karoo 2.

The Karoo has both a touchscreen and two buttons on each side. That's brilliant. For many actions you can choose between touch or button: the best of both worlds. The touchscreen is otherwise acceptable, but certainly not outstanding. If I swipe 10 times I'm still 1 or 2 times wrong.

The charging goes as it should via a USB C-port. In the first batch, this port had no cap or cover. If you buy one now, you get two separate rubber caps with it. That cap, however, vibrates very easily and is therefore easily lost. It would have been much more convenient to make the cap a physical part of the device. Separately, our test device on the computer hardly wanted to recharge. Only with a strong 10 or 20W charger did we get the battery full.

The casing makes a solid impression, and so do the buttons. The device seems to be able to take a beating. For mounting, Karoo came up with its own standard. An out front holder is included. Personally, I'd rather see manufacturers use existing standards, instead of coming up with their own that you're stuck with. In my opinion, the Karoo attachment offers no advantages at all over the quadlock used by other brands. You do get an adapter with which you can convert it to quadlock (Garmin fitting). Unfortunately, there's play between the adapter and the Karoo. I recommend immediately upon purchase to glue it down with super glue, then you have nothing to worry about.

The Karoo has ANT+, Bluetooth, WIFI and of course a barometric altimeter. The altimeter is good and accurate. The wifi chip does have some trouble with some wifi networks.

Let's talk about the form factor. The fact is that the Karoo is (and looks) a lot smaller than the Karoo 1, which was sort of half an iPad. Still, I find the device by no means elegant. The much longer Edge 1030/1040 look smaller, while in reality they are longer. The device is also quite thick at 28 mm. The weight of 186 grams is also considerable (some 50-80 grams heavier than the competition).

It is worth noting that the device was stable and never crashed. On the other hand, the Karoo isn't the fastest device out there. From a phone you would expect something more. The reason is probably that the processor is slowed down quite a bit to save the battery.

Connectivity and sensors

Setting up the Karoo is easy, you start up the device and everything is self-explanatory. You can connect your phone via bluetooth, which allows you to see apps and calls while riding, if you want to of course. If you use Android you have to install an app for this on your phone, on an iPhone this is not necessary. The connection with the phone remained stable during our test period, although it sometimes took a while (6-10 seconds) before messages and calls came through.

Connecting sensors goes without a hitch. Like Garmin, Karoo works with a fold-out screen from above. What is very unfortunate is that Shimano has withdrawn Di2 support, as Hammerhead is now part of SRAM and thus seen as a competitor. It's lame, but effective. For Di2 riders the device is therefore no longer interesting. When I received the device, the old firmware was still on it and I was able to test the Di2 functions. It is on a par with Wahoo, but not as good as Garmin. No gear adjustment mode, no 50x11 format for the gears and no beep at your lightest gear. But otherwise it just worked as it should.

No companion app

Hammerhead does not have a companion app. However, there is an online dashboard (website) where you can easily link Strava, Komoot, RidewithGPS and a whole bunch of other platforms. Routes are then automatically synced as soon as you start up the Karoo. The dashboard also allows you to draw routes or upload a separate GPX. Unfortunately, you can't adjust settings on the Karoo in the dashboard, this can only be done on the device itself.

The fact that there's no companion app has one very important consequence: the Karoo can't use your phone's internet connection. For a number of actions, every bike computer, including the Karoo, needs internet. Think of loading a route, uploading a ride and live tracking. At home, you will usually do this via wifi. If you want to do this on the road, you have a problem with the Karoo. Karoo prefers you to put a data SIM card in the device. However, in many countries this is quite an expensive option. A workaround is to make a wifi-hotspot of your phone, but that is laborious and (especially with live track) costs a lot of battery.

User friendliness

The Karoo is pretty user-friendly. Everything is self-explanatory and the user interface (UI) looks fresh. The Karoo uses the well-known OSM maps that you have to download when setting up. This takes some time but is not difficult. The internal storage of 32 GB is not very spacious. Downloading NL, Belgium and France costs 13 GB.

What is nice is that there are not too many settings like Garmin. It is really less = more and therefore even technophobes will be able to fathom the device quickly. The UI contains a number of clever features, such as a drop-down menu with several tabs. Also, climbing profiles and Strava segments are displayed with a dynamic pop-up, which is very clever.

The Karoo has bike profiles which is a big plus over Wahoo. A downside is that you can't back up the settings. If you need to reset the device, you have to create all profiles and pages again. The creation of data pages is, however, via the settings menu. This is super easy and simple. Unfortunately you can't change a data field while driving with a long press, as with Garmin.

Navigating with guidance

Navigating is where the Karoo aims to stand out from the rest. After you've created and loaded a route via the dashboard, let the Karoo sync up and click the route. If you want, the Karoo will take you to the start, although you have to click this yourself while the competition pro-actively asks you to do so.

The directions are at the bottom of the screen (see photo) and are clear. As long as it doesn't get too complicated, you can feel free to keep a regular data screen in view and rely on the clue. Just before the junction, the street name is added to the direction (this can be turned off). The navigation line itself is yellow, which is not adjustable but that's not necessary. The line also contains arrows as extra help (the so called chevron).

Picture: the direction is at the bottom of the screen.

A big disadvantage is that recalculation cannot be turned off separately. Guidance can be turned off, and then you also turn off recalculation. Recalculating is an option which causes more trouble for many users than it saves (see box). Of course we have tested recalculating extensively. Positive is that recalculating is very fast. The redirections are illogical or even blatantly wrong in about 30% of the cases. This is not worse than the competition, but also not better.

Picture: Just before the turn, the street name comes up in the direction.

While navigating, you can zoom in on the map with your fingers or via the buttons. You can also move the map around (panning). That works just fine.

The Karoo plots your "tail" (where you've been) with a thick gray line on the map. What I find annoying is that it is projected below the yellow navigation line. Therefore it is not very visible. Another disadvantage is that there is very little you can adjust to the navigation. We already mentioned turning off recalculation, but auto zoom is also missing. Reversing a route cannot be done on the device itself (it can be done via the dashboard). Switching automatically from a data page to the map screen at an intersection is also not possible. Beeps can fortunately be turned off.

A plus point is that the layout of the map is very clear, partly thanks to the beautiful screen. A "surprise me" function, where the device maps out a lap of X number of km for you, the Karoo doesn't have.

Why is recalculation so difficult for a bike computer?

Recalculation is one of the trickiest things to program for any bike computer manufacturer. There are two reasons for this.

First, a bike computer can't determine whether you accidentally drive the wrong way (you miss a turn) or whether you deliberately drive the wrong way (road closed). Second, on a bike you're mostly doing loops, unlike in a car where you usually drive A>B. Car navigation can always assume the final destination as the goal, while a bike navigation wants to stay true to the loop.

However, a bicycle computer can never know if a closed road might be open again further down the road. The very first bike computers with navigation solved this by calculating the fastest way to the final destination, just like a sat nav in a car. This sometimes led to bizarre situations in which if you made a mistake at the start of the route, you would find yourself back at your house a few miles later....

Nowadays, bike computers use a slightly different algorithm: they take a point on the route X number of km further than the point where you went wrong and try to lead you there. That can work out well, but in the bad case you can miss a good portion of the original route.

Navigating without guidance

Personally I prefer to navigate without guidance, I find that a lot calmer and clearer. This works very well on the Karoo 2. The line is as mentioned very clear and thanks to the chevron you don't have to hesitate even when routes intersects itself. What is inconvenient is that you lose your chevron as soon as you zoom out further than 200m.

On the map screen you can put up to 6 data fields. In my opinion these fields do take up a lot of space. If you have 4 like me, they take up 40% of the screen. I'd rather have smaller data fields and a bit more map.

Navigating to an address

Of course, the Karoo can also navigate to an address or point on the map. This works well. A disadvantage is that you need (temporary) internet. If you don't have a SIM card in the Karoo and no wifi connection, you have to make a hotspot of your phone. An advantage, however, is that you do not need to know the address ("Marriot Hotel" in Amsterdam). The algorithm is not adaptable (yes/no ferry, yes/no unpaved, etc.). This is a huge disadvantage, especially for gravel riders or people who live in an area with a lot of water (ferries!). On the other hand, navigating to an address is also a functionality you rarely use.

Live tracking

To test this, I made a hotspot of the phone, since I didn't have a SIM in the Karoo. This of course cost the phone a lot of battery, but on its own it worked correctly. The link for sharing your location is taken from the Dashboard. Strange that one of my spectators saw all the data in miles/feet, and others just metric. The spectator sees the speed, distance traveled and total distance route. What you don't see as a spectator: power, heart rate, distance to go and ETA. This could really be better. In this way, you might as well share your location via WhatsApp.

Climb profiles

The Karoo can display the profile of a climb while cycling. You can turn this on and off, if desired you can choose not to display it for shorter climbs. Garmin and Wahoo have similar functionality, but Karoo's is superior. For example, the profile appears as a clever pop-up over another data screen. If you want more detail you can expand the screen further, or drag it away if you don't feel like it. The profile itself is very clear and looks nice (see photo). A nice detail is that the climb profile also works if you have not loaded a route (this in contrast to the competition). The maps on the Karoo however have a low resolution regarding the altitude data, so it is a lot less accurate than when you load GPX.

Photo: The climbing screen.


Many Karoo 2 users are quite lyrical about the device. So I went into the test period with high expectations. Those expectations were partially met. The screen is definitely THE big plus of the device. It is also nice to see that many new features have been implemented recently. The climbing profile is the best on the market at the moment. I don't think the mounting adapter is a logical choice (nor is it well designed), but it could live with.

The question is would I buy the device myself? The answer is no. I ride with Di2, occasionally take part in a long gran fondo and the fact that you often have to make a hotspot of your phone are the showstoppers for me. I also have good eyes and I find the device just too big and too heavy. On top of that, for the same money (€399) you have a Wahoo ELEMNT Roam and for 50 euros more a Garmin 1030.

Would I recommend the device to others? I might. For people who have somewhat impaired eyes, don't do hugely long rides and are looking for the best screen, the Karoo 2 could be a great choice. I also think that technophobes will be quite happy with the device although then Wahoo is also a good choice.

In my opinion, there are still a lot of big and small areas for improvement in both hardware and software. Many readers may feel that I am too harsh in my judgment. But remember: Hammerhead has been around for over 5 years and this is already their second device. In that time they have come quite a long way, but the only conclusion I can draw is that Garmin and Wahoo still have a pretty big lead. Hammerhead obviously only has a small team of developers, but now that they have been acquired by SRAM that will probably improve. In terms of navigation and features I put Garmin really one step higher (sorry Garmin-haters ;). In terms of user-friendliness Wahoo is in my opinion the industry standard. Are they on the heels of these companies? Certainly. The Karoo 3 could well become a killer. The Karoo 2 is not, as far as I am concerned.

Final grade: 7


+ screen
+ build quality
+ user friendliness
+ nice climb screen
+ number of smart solutions in the UI
+ touchscreen and buttons
+ less = more device


- battery life is really poor
- proprietary standard for mounting that has no advantages
- play on the adapter
- UBS-C port cover is easily lost
- No companion app, therefore no possibility to use internet phone (without hotspot)
- Live tracking could be better
- certain crucial options in the software are missing
- relatively heavy
- No Di2 support anymore
- not always fast
- not a competitive price (€399 ex. sensors)

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