Hammerhead Karoo 2 Review: Smartphone-Like Experience

Hammerhead Karoo 2 review: Me holding Karoo 2 in my hand in front of a green blurred background.

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This is my Hammerhead Karoo 2 review. I already tested some high-end bike computers like Garmin Edge 1040, but I was looking forward to scrutinizing Karoo 2 because of its display and user interface based on Android.

Below, you will learn how it stands against other bike computers, its main disadvantages, where it excels, and more.

IN SHORT: Karoo 2 offers a smartphone-like display, which makes it ideal for using maps. It’s bright, responsive, and easy to read. Karoo 2 also has a Climber and many more features. Its main disadvantage is short battery life.

You can buy it here or read my entire review for more info.

Hammerhead Karoo 2 Pros & Cons

These are the main pros & cons of Hammerhead Karoo 2 I found during its use.


  • Beautiful and responsive display
  • Easy-to-read
  • Easy to use (the UI is intuitive, fast, and responsive)
  • Full on-device navigation
  • Great navigation and mapping experience
  • Climber feature
  • Internal memory of 32 GB
  • Quarter-turn adaptor included
  • USB-C charging port
  • Ability to change the case color by using custom color kits


  • Slow start-up time (about 55 seconds)
  • Short battery life of ~8.5 hours (1-year-old device, measured in temperatures below 5°C [41°F])
  • Display doesn’t work well when wet
  • Proprietary mount
  • Requires internet for syncing routes, activities, loading maps, LiveTrack, etc.
  • Not compatible with Shimano Di2 groupsets (this is rather Shimano’s fault)
  • Badly designed charging port cover
  • No dedicated smartphone app
  • Sometimes buggy software

Also available at wiggle.co.uk and wiggle.com

In the Box

The stylish premium-like black box of Karoo 2 includes the standard contents we are used to.

  • Hammerhead Karoo 2
  • Quarter-turn adaptor
  • USB-C charging cable
  • Tether
  • Allen key
  • Manual

Initial Setup

The initial setup of Karoo 2 is straightforward. You basically connect to WiFi, and Karoo updates its firmware. Then you log in to your Hammerhead account (by scanning a QR code).

After that, Karoo shows some initial tips on pairing Strava and sensors.

My Experience with Hammerhead Karoo 2

I had no idea what to expect from Karoo 2. I read some user reviews but wanted to make my own opinion.

Karoo’s system runs based on Android. Thanks to the powerful processor, it’s very responsive. It’s like using a smartphone.

I was surprised that it felt faster than Garmin Edge 1040. So, my first impressions were positive. Read my entire comparison of Karoo 2 vs. Edge 1040 for more details.

So, what I noticed during about a month of use? Here are my main takes:

  1. The display is like no other. It has super high brightness and resolution. But it’s not perfect (more about it below).
  2. The system takes a long time to boot, but it’s responsive and intuitive.
  3. Setting up data pages and data fields includes a dynamic preview of individual fields.

Let’s now dive deeper into individual features.


The 3.2-inch display is (very) bright and responsive. I had no issues reading it, even in direct sunlight.

It has a 480×800px resolution, almost double the pixel density of Edge 1040 with 282×470px.

When setting up data pages, you can choose from many page layouts. However, the number of data fields per page is limited to 10.

Hammerhead Karoo 2 with a layout settings open.
Layout settings

What I like, though, is the graphic representation of how the data fields look. Check out the following video for examples.

Karoo 2 shows field previews, so you know how they look

Control & User Friendliness

This was the area I was most curious about because that’s what Hammerhead markets as the ‘next level.’

And it honestly felt like that. I highly appreciate Karoo’s responsivity. It has an intuitive user interface, so I had no issues finding features I needed (unlike my first time with Garmin head units).

Although there is no Hammerhead smartphone app, I don’t think you will need one. Setting data pages and data fields is easy on the device itself.

As always, I tried the display’s controllability with gloves and when wet. It works fine with gloves but freaks out when it’s water on it. Even when you wipe the water off, it struggles. Watch the following video.

Showing the control of Karoo 2 with gloves, without them, and when wet

However, the unit still has 4 buttons (2 on each side) that allow you to easily control it.

I also sometimes encountered buggy software. For example, I couldn’t click on the notification about the low battery life of my bike radar, and the Karoo 2 beeped for half a minute before it stopped. Annoying.

Maps & Navigation

Thanks to the responsive and touchscreen display, Hammerhead Karoo 2 is perfect for browsing maps and navigation purposes.

Hammerhead Karoo 2 with a map layout settings open.
Maps page with additional info

Its maps are pretty detailed. It can navigate you to points of interest, dropped pins, addresses, etc. Of course, it can recalculate the route when you go off-course.

I am not a frequent map user, but I must admit that Karoo 2 provides the best mapping experience of all bike computers I tested.

I am gonna repeat myself, but it’s (almost) like browsing maps on your smartphone. So smooth… You can even change the view angle from a 2D view to a 3D-like view.

Karoo 2 calculates routes almost instantaneously.

Climber Feature

The Climber feature is one of the features I like the most about Karoo 2. It’s similar to Garmin’s ClimbPro, but it doesn’t require having a planned route.

If you don’t know ClimbPro, it’s a feature that shows you information about the upcoming climb, like its gradient, distance to the top, and many more metrics you can set up.

It’s perfect for long rides because you can better manage your pace and resources.

Of course, Climber is not perfect and sometimes misses a climb. In the end, it’s just guessing the route you’ll take. But if it nails it, it looks like this:

Hammerhead Karoo 2 showing a climb details using the Climber feature (full-screen).
Hammerhead Karoo 2 Climber feature (full-screen)

Or you can minimize it (to see your other metrics) the same way as the following Strava live segment tab (the Climber tab is next to Strava):

Strava live segment page on Hammerhead Karoo 2.
Strava live segments on Karoo 2 (apologies for the low quality)

GPS Accuracy

The Karoo 2 has GPS and GNSS connectivity but lacks multi-band GNSS. I compared its accuracy with other bike computers.

Surprisingly, Karoo 2 had similar accuracy as Edge 1040 (which has multi-band GNSS) in my testing segment.

However, the 2nd test (when I started the ride in the forest and returned back on the same route) ended up a little worse (but still pretty accurate).

Take a look at the results in the following gallery:

Unfortunately (or maybe thank God), we don’t have many high-rise buildings in the Czech Republic (or my area). So I couldn’t test the GPS accuracy in an urban area.

Battery Life

The relatively short battery life is the most significant Karoo 2 weakness.

Hammerhead claims it can last up to 12 hours. My device was already used for about a year (I bought it second-hand).

I connected to it all my sensors; these include a power meter, HR monitor, and cycling radar.

It lasted me about 8.5 hours. Surprisingly, the last 8 % lasted for almost 2 hours. I tested the device in winter at temperatures below 5°C (41°F). I set the display brightness to 50% because Karoo 2 does not have an ambient sensor. This brightness was overkill for the dark winter days.

Because the brightness drains the battery the most, I am sure Karoo 2 would last longer at a more conservative setting.

Even so, its battery life is short compared to Wahoo ELEMNT BOLT v2 or ROAM (~15 hours). Garmin Edge 1040 and 1040 Solar are in a league of their own (30 and more hours).

Another problem is the badly designed charging port cover. It’s not attached to the head unit, so it is easy to lose it. Before I could even get a picture of it, I lost it.

I also came across the Karoo support page and read the following info about the charging:

Karoo 2 does not support charging over 5V. The maximum current flow is 2.5 Amps but only during 0-30% charging. Regular charging is around 1.25A so high amp or high voltage chargers could be dangerous or damage the product. (Source)

I don’t know about you but thinking about what charger I use for which device doesn’t seem right to me.

This is clearly an issue Hammerhead should address. Shifting this responsibility to the customer is concerning because the device should maintain the current flow.

Also available at wiggle.co.uk and wiggle.com


The Karoo 2 has Bluetooth, Wi-Fi, and ANT+. However, you will need Wi-Fi for most of its features (like downloading maps or syncing routes).

So, if you are a bike packer who has no access to an internet connection all the time, Karoo 2 is not for you.

Another issue is Shimano plays a dirty game. You know, Hammerhead is owned by SRAM, which is Shimano’s direct competitor.

They ordered Hammerhead to remove Shimano Di2 features from their head units. I don’t like this game at all because not only that Hammerhead loses potential customers, but in the end, we, the consumers, lose.

You can watch the following video for more info.

DC Rainmaker explains Shimano × Hammerhead ‘battle’

Check out this workaround to have Di2 features on the Karoo 2 again.

Hammerhead Karoo 2 Alternatives

Here are some Hammerhead Karoo 2 alternatives worth considering.

  • Garmin Edge 1040 (Solar) is Garmin’s flagship bike computer with a larger display, much longer battery life, and more unique features. On the other hand, it’s more expensive.
  • Garmin Edge 1030 Plus is the predecessor of Edge 1040. It has an old UI, fewer features, and shorter battery life. But it still belongs among capable bike computers.
  • Wahoo ELEMNT ROAM v2 is easier to use thanks to its intuitive user interface. It’s button-based and has longer battery life.

Hammerhead Karoo 2 FAQ

Hammerhead Karoo 2 Technical Specifications

Below I summarized Hammerhead Karoo 2 technical specifications.

Technical specifications

  • Battery life: 12 hours
  • Display: 3.2in / 81mm (480×800px)
  • Touchscreen: Yes
  • Weight: 131g
  • Dimensions: 60.8×100.6×19.3 mm
  • Strava live segments: Yes
  • Smart trainers control: Yes
  • Smart navigation (rerouting): Yes
  • Crash/incident detection: No
  • Connectivity: ANT+, Bluetooth, Wi-Fi
  • Waterproofing: IP67
  • Storage: 32GB


Karoo 2 is one of those products that you don’t know exactly what to expect. In some ways, it disappoints, but in many ways, it surprises.

I appreciate Hammerhead’s innovative approach. The Karoo 2 display and system are great, except for the little things – and poor controllability when wet.

The display makes the Karoo 2 ideal for those who frequently interact with their bike computer. For example, for navigation and maps.

The most significant disadvantage is the short battery life, so be prepared for frequent charging.

Overall, it was refreshing to use Karoo 2 after testing its alternatives. I look forward to future software updates and improvements.

There are many things that need to be fixed and improved, but Hammerhead is serious about biting off a bigger chunk of market share. So, consumers like you and I should benefit from this.

Also available at wiggle.co.uk and wiggle.com

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