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 review of the Hammerhead Karoo 2. While I’ve tested some high-end bike computers like the Garmin Edge 1040, I was eager to scrutinize the Karoo 2 due to its Android-based user interface and display.

Below, you’ll learn how it compares to them, its main disadvantages, where it excels, and more.

IN SHORT: Karoo 2 offers a smartphone-like display, making it ideal for using maps. It’s bright, responsive, and easy to read. Additionally, the Karoo 2 has a Climber and many other features. However, its main disadvantages are short battery life and bad controllability when the display is wet.

You can buy it here or read my complete review for more information.

Hammerhead Karoo 2 Pros & Cons

These are the main pros and cons of the Hammerhead Karoo 2 that I discovered during 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
  • The 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])
  • The 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 competitivecyclist.com 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 the Karoo 2 is straightforward. You’ll connect to WiFi, and the Karoo will update its firmware.

Then, you’ll log in to your Hammerhead account (by scanning a QR code) and provide some initial tips on pairing Strava and sensors.

My Experience with Hammerhead Karoo 2

I wasn’t sure what to expect from the Karoo 2. While reading some user reviews, I wanted to form my opinion.

The Karoo’s system is based on Android and is very responsive thanks to its powerful processor. It’s like using a smartphone.

I was surprised it felt faster than the Garmin Edge 1040, so my initial impressions were positive. Check out my full comparison of the Karoo 2 vs. Edge 1040 for more details.

So, what did I notice during about a month of use? Here are my main takeaways:

  1. The display is like no other, with super high brightness and resolution. However, it’s not perfect (more on that below).
  2. The system takes a while to boot up, but it’s responsive and intuitive.
  3. Setting up data pages and fields includes a dynamic preview of each field.


The 3.2-inch display is incredibly bright and responsive. I had no trouble reading it, even in direct sunlight.

It boasts a 480×800px resolution, nearly double the pixel density of the Edge 1040, which has 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

I appreciate the graphic representation of how the data fields look when selecting a layout, as demonstrated in the following video.

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

Control & User Friendliness

This was the area I was most curious about, as it’s what Hammerhead markets as the “next level.”

And honestly, it lived up to the hype. I greatly appreciate Karoo’s responsiveness. The user interface is intuitive, so I had no issues finding the needed features (unlike my first time with Garmin head units).

While there is no Hammerhead smartphone app, I don’t think you’ll need one. Setting up data pages and fields is simple on the device itself.

As always, I tested the display’s controllability with gloves and when wet. It works fine with gloves, but it struggles when wet. Even wiping the water off doesn’t always help. Watch the following video to see what I mean.

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

However, the unit still has four buttons (two on each side), allowing easy control.

I did encounter some buggy software at times. For example, I couldn’t click on a notification about my bike radar’s low battery life, and the Karoo 2 beeped for half a minute before stopping. It was quite annoying. Unfortunately, it didn’t happen just once, but several times.

Maps & Navigation

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

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

Its maps are pretty detailed and can navigate you to points of interest, dropped pins, addresses, and more. It can also recalculate the route when you deviate from the original path.

I’m going to repeat myself, but I must admit that Karoo 2 provides the best mapping experience of all bike computers I have tested, even though I am not a frequent map user.

Browsing maps on Karoo 2 is almost like browsing maps on your smartphone. The experience is so smooth. You can even change the view angle from 2D to a 3D-like view.

Karoo 2 calculates routes almost instantaneously.

Climber Feature

The Climber feature is one of my favorite things about Karoo 2. It’s similar to Garmin’s ClimbPro, but doesn’t require a planned route.

If you’re unfamiliar with ClimbPro, it’s a feature showing information about upcoming climbs, like gradients, distance to the top, and other customizable metrics.

Climber is perfect for long rides because it helps you manage your pace and resources more effectively.

However, it’s not perfect and sometimes misses a climb. Ultimately, it’s just guessing the route you’ll take. But when it gets it right, it looks like this:

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

You can also minimize the Climber feature to view other metrics by following the same steps as minimizing the Strava live segment tab located next to the Climber tab.

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 Karoo 2’s relatively short battery life is its most significant weakness.

Hammerhead claims it can last up to 12 hours, but my second-hand device, which I used for about a year, lasted about 8.5 hours with all my sensors connected, including a power meter, HR monitor, and cycling radar.

Surprisingly, the last 8% of battery life lasted almost 2 hours. I tested the device in temperatures below 5°C (41°F) during winter, and I set the display brightness to 50%, which was overkill for the dark winter days since Karoo 2 does not have an ambient sensor.

The display brightness is the biggest drain on the battery, so I’m confident Karoo 2 would last longer in a more conservative setting.

However, even with a more conservative setting, its battery life is still short compared to the Wahoo ELEMNT BOLT v2 or ROAM (~15 hours). The Garmin Edge 1040 and 1040 Solar are in a league of their own, with 30 hours or more.

Another problem is the poorly designed charging port cover, which is not attached to the head unit, making it easy to lose. I lost mine before I could even take a picture of it.

I also came across the Karoo support page and read the following information about 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 having to think about which charger to use for each device doesn’t seem right to me.

This is an issue that Hammerhead should address. It’s worrying that the responsibility is being shifted to the customer because the device needs to maintain the proper power flow.

Also available at competitivecyclist.com and wiggle.com


The Karoo 2 has Bluetooth, Wi-Fi, and ANT+ capabilities, but Wi-Fi is required for most of its features, such as downloading maps or syncing routes.

Therefore, if you’re a bike packer without regular access to Wi-Fi, the Karoo 2 may not be suitable for you.

Another issue is that Shimano appears to be playing unfairly. Hammerhead is owned by SRAM, Shimano’s direct competitor.

As a result, Shimano has instructed Hammerhead to remove Shimano Di2 features from their head units.

This game is troubling because it causes Hammerhead to lose potential customers and ultimately hurts us, the consumers.

You can watch the following video for more information if you’re interested.

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


The Karoo 2 is a product that can be unpredictable. In some ways, it can disappoint, but in many ways, it can surprise.

I appreciate Hammerhead’s innovative approach. The Karoo 2’s display and system are excellent, except for a few minor issues, such as poor controllability when wet.

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

However, the most significant disadvantage is the short battery life, which requires frequent charging.

Overall, using the Karoo 2 was a refreshing change compared to its alternatives. I’m looking forward to future software updates and improvements.

Although many things need to be fixed and improved, Hammerhead is serious about increasing its market share. As a result, we, consumers, should benefit.

Also available at competitivecyclist.com and wiggle.com

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