Hammerhead Karoo 2 – a review

Two years ago I took the big step and bought myself a proper bike computer (or a head unit), a Wahoo ELEMNT Bolt. This action felt like a rite of passage, progressing from being a casual cyclist to becoming a passionate data-driven amateur cyclist (define as you will). It promised the collection of large amounts of data, such as cadence, heart rate and power, as well as showing maps and recording rides. At that stage, it was more than enough for my purposes.

The Wahoo is a very good bike computer, and even the upgrades to the new Bolt are pretty marginal, a testament to the quality of the original (although the new colour screen is pretty cool). As I became more interested in long-distance riding and audaxes (such as Berlin-Munich), the small screen became a bit of an issue. I was also looking for something with a colour screen, detailed maps useful for orienting, and a clearer elevation profile for upcoming hills (I no longer hate climbing).

Whilst the new Bolt wasn’t really a contender, I did think about an upgrade to the Wahoo ELEMNT Roam. The maps are good, however this still didn’t offer the climbing profile I wanted. Unfortunately Wahoo only offers general profile and current gradient, rather than a detailed breakdown of upcoming segments which would allow the user to plan efforts.

Garmin’s 830 and 1030 Edge were interesting, as these seemed to to tick most of the boxes, including the climber function and an app store which adds functions such as wind direction. From their optics however, these however felt a little dated, and – whether or not a fair judgment – I had the impression that Garmin had a reputation for reliability issues.

Given that no major releases for either were published at the time for either Wahoo or Garmin, I wasn’t keen on spending a lot of money on something where I had doubts. That’s where the wildcard came in – the Hammerhead Karoo 2.

The Karoo 2

Over the past few months, I’ve been bombarded with adverts of the Karoo 2 on Instagram and Facebook, and originally I just rolled my eyes and over time became increasingly irritated. Just as any good advertising should do though, it sew a seed, which – coupled with my search for a new computer and dissatisfaction of the current market offerings – flowered into an idea.

Hammerhead played it well, offering a 45 day no-commitment trial period. One day I took a punt and ordered the Karoo 2, with the idea lingering in the back of my mind of getting a Garmin if it didn’t work out. About a later, the K2 came in the post.

For the first day or two, I was quite sceptical of the K2, but its performance and quality quickly grew on me. After about a month of using it, I discovered that the altitude values were inconsistent over routes I regularly rode, and I later had some sensors cutting out, in particular one of my power meters. This is where Hammerhead’s customer service really shone, and one technician asked me to send over my ride data and made some practical suggestions after analysing it. After several attempts to remedy this, I was sent over a replacement computer, and indeed it appeared that the original model had some minor problems. Since I received the new computer, I haven’t had a single issue.

Map display of the K2 on the highest zoom out mode. Here you can see saved Strava segments in orange, bike paths in green/white, and international cycle routes in green.

I don’t want to do an in depth product review, and I defer to more capable reviewers such as road.cc, CyclingNews and DC Rainmaker. Instead, I felt like putting my thoughts into words after using the computer for several months. Perhaps this might help someone who is in a similar position to myself.

To keep things to the point and fun, I have listed 3 things I don’t like, 3 things I do like, and then a short summary.

Disclosure: I am not sponsored by Hammerhead and have paid for the Karoo 2 in full with my own money. The below is purely my unbiased opinion based on my experience.

3 things I don’t (quite) like…

  • The K2 has a USB-C port which I like, however it’s protected by a tiny rubber plug which I’m sure I’ll lose soon. In comparison, the Wahoo ELEMNT Bolt has a plug which is built into the body. This is a much cleaner solution and more practical as it can’t be lost. That being said, this point is addressed on the Hammerhead website, and it appears the USB C port is waterproof even without the plug. [Update: this problem has been remedied, see point “Another Update” below]
  • After using the mount for the Bolt, the K2 specific mount feels a little too clunky and heavy. I don’t really use this however, as the K2 does come with a Garmin adapter. Unfortunately there is no Wahoo adapter available. That being said, I have bodged my current Wahoo holder to adapt to the Garmin mount.
  • This is an odd one, however having the software regularly updated somehow makes the K2 feel a little experimental. When you buy the Bolt (and presumably Garmin products), it feels that you are buying a product which has been fully tried and tested, and over its lifetime may receive minor updates. In comparison, Hammerhead is clearly a startup and it does appear to rely on its community to perfect the product. Over successive major and minor updates since I received it however, I get the impression that the K2 is becoming more refined – anybody buying this now with the benefit of these upgrades will certainly receive a very sophisticated computer, comparable with offerings from Wahoo and Garmin.

3 things I like…

  • The K2 build quality is very good – it feels solid but not too heavy, and the screen is large and presents data very clearly. Upgrading from the Bolt, the map screen is incredible, with a high level of details and POVs presented without the data being overwhelming.
  • The K2 has the perfect mixture of touch screen and buttons – if it starts raining, the big grippy buttons on the sides cover all normal functions. I have only used the K2 in winter so far, but with touchscreen compatible gloves, the screen is easy to use, and I often find myself using the physical buttons as much as (if not more than) I use their touchscreen equivalents. The computer even has a tiny on-screen keyboard (which can be used to write up ride descriptions) which is surprisingly easy to use given its size.
  • The K2 really feels like a community-driven project. The website has an active forum where many users suggest developments which may materialise in the fortnightly software updates. This is linked to my third point above. One example is the new app store function which was released just after I bought the K2. This has however disappeared again, but I presume it will reappear again when it has been improved. As noted above, the customer support is great.
Data field mode. These are fully customisable and can include charts and graphics.

The conclusion?

The bike computer market for amateurs / professionals right now feels like the mobile phone market must have done before the iPhone was launched. Much like Nokias, Motorolas and Sony-Ericssons of the early 2000s, every bike computer model has a standard set of features and sensors, and this is the main reason you buy a specific model. Afterwards, you may get a minor updates once in a while to remove bugs and add one or two features.

I feel like Hammerhead has taken the opposite approach, where you buy a headset with an array of sensors, and the software (and its updates) is the actual product. This is the part that actually polarises me a little. I’m not sure I like paying for something that is arguably not finished, but that being said, the potential is massive.

With increasing concern on environmental sustainability and concerns about our throw-away culture (including the cycling sector), it doesn’t quite feel right to buy a new headset every few years whenever either (i) a new model is released, or (ii) the old model no longer fulfils our needs. Think of all the old mobile phones, other electronic devices and cables you have squirreled away at home, especially the plastic and precious metals used to produce these.

I like the current offering of features the K2 has, but the idea of a continuously developing software and a new app store for third party developers is really intriguing. This should mean that a single device should still be relevant and modern in 10 years. With the EU “right to repair” initiative, this may be an important step in developing the environmental sustainability creds of cycling.

Whilst my experience with product support has been very impressive so far, my original concern was that in the future the standard of support may no longer be the same, or that Hammerhead may lose interest when a new model is released. Their customer support and engagement clearly differentiates them currently as a newbie from the incumbents in the bike computer market, but can they guarantee that the updates will still be regular and of high quality, and that my K2 will still be still a competitive product in 10 years? The recent purchase of Hammerhead by component giant SRAM would however suggest that the product will not just be a short term fad.

For the price tag of less than the top range Garmin model with similar functions, this is however a risk I’m comfortable to take.


Hammerhead regularly makes updates to the Karoo 2 – to keep this post fresh, below I comment on the more important ones and provide general updates:

  • April 2022: Just after I wrote this post, Hammerhead released a new feature called “Predictive Path Technology”. This means that – even if a path hasn’t been uploaded – the K2 will predict the path you take and display the climbing profile. I’m not sure if this is new in the market, but two weeks ago I initiated a route up my local climb just so I could see the profile. This didn’t work well, as the routing algorithm tried its hardest to avoid the climb. This new update solves this problem, and just reassured me that the community development approach of Hammerhead really will lead to a great product that just gets better.
  • August 2022: In August 2022, I rode the 1500km ultra-audax Berlin-Munich-Berlin (my story here). Over the 6 days of riding, I had absolutely no problems with the Karoo 2. The routing was reliable, the map screen clear and the rerouting system was extremely helpful if I missed a corner or a road was closed. The Climbr function was useful in planning efforts up hills. Several fellow riders complained about issues with their computers, but I can’t speak to this. Frankly, I was very impressed with the Karoo 2. Despite a common complaint compared to the Garmin 1030 or 1040 is the K2’s slightly shorter battery life, however over such a long distance this is really irrelevant – I always had my battery pack with my in my top tube bag, and regularly recharged my computer even at 50% to make sure I was on the safe side.
  • September 2022: In early September 2022, I discovered that Hammerhead had developed a new hardware update – a new shell part which included an integrated rubber cover for the USB-C port. This new shell piece will be mounted onto every new Karoo 2 sold. Whilst a minor inconvenience to pay a small amount of money for this part, it just confirms that Hammerhead listens to its users – not just for software updates, but for hardware. My praise for Hammerhead couldn’t be higher.
A hardware update with the new integrated charging port cover. Just remove the screws and swap out the covers.
  • February 2023: A slight moan from me this time – I’ve just started structured training using TrainerRoad. The K2 offers seamless integration with competitor TrainingPeaks, however there is nothing official for TrainerRoad. This means I cannot properly upload training sessions onto the screen when I’m riding outside. Instead, I’ve tried “sideloading” the TrainerRoad app (i.e. unofficially installing the app, as the K2 is essentially an Android powered computer). The idea is really compelling, however there are a few drawbacks. The app is very slow to load and doesn’t properly integrate into the screen when recording rides outside. TrainerRoad officially cooperates and integrates with Garmin and Wahoo, so I’m planning on using my old Wahoo ELEMNT Bolt at the same time for training until Hammerhead offers full integration. It’s a shame, but unfortunately one of the very few downsides of the K2. I’m however certain that this will be remedied in the future.

Have you bought a K2? Do you agree or disagree with my thoughts?


4 thoughts on “Hammerhead Karoo 2 – a review

Add yours

  1. Nice review. I bit the bullet and bought the Karoo 1 when it came out because I loved that they were using more of an “open source” system…Android. I knew that opened up the possibilities for the head unit. When the Karoo 2 came out I thought about keeping the Karoo 1 and buying the Karoo 2 but they offered a great trade in price so I traded it in. I loved the Karoo 1 but the Karoo 2 does have more features and it was worth the upgrade.

    What you call a “think you don’t like” (it feels like an unfinished product due to all of the updates), I consider that a HUGE advantage. They are utilizing the Tesla model, which is you buy the product and you will continue to get updates that actually add new features to the unit that increase the functionality as well as the value of the unit. I LOVE that model!!! I wish there were more companies out there that would do that.


    1. Thanks for your comment, its good to see I’m not the only one that thinks this way! I agree the point “things I don’t like” is a little unfair, however I entirely recognise this is something that is becoming increasingly irrelevant as the device has already reached parity with my Wahoo. When I bought the K2, there were still a few niggles which have been quickly remedied, and I’m very curious to see what they do with the shop app which so mysteriously disappeared. My only concern now is that this level of service will continue, even if a new model comes out, however SRAM’s involvement gives me confidence. Thanks again and happy riding!


  2. Hey. Thanks for you review of the K2. Very useful as I’m thinking of purchasing one.
    How do you find the battery life on your longer rides? This is my biggest concern around the K2 and holding me back. I also like Audax rides, although just starting out.

    Liked by 1 person

    1. Thanks for your comment! I’ve heard the discussion about the K2 v Garmin 1030/1040 quite a bit, and I personally find the battery life argument a bit of a red herring. From experience I get about 9-11 hours from my rides on the K2, depending on which features are active. Hammerhead has a page on their website where it shows which functions consume more power, but the device also has a battery saver mode. For any long trips such as audaxes, I would always bring a battery pack for lights and my phone, so the battery life problem is effectively solved, unless you really need an extra 1 or 2 hours of power without a battery pack. Battery life aside, the countless other functions that the K2 has, the clean and detailed display, as well as the regular updates and new features really sway it for me. I have thought often about whether I should have got the 1040 instead, but I really have no regrets. Good luck in your choice, and happy riding!


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