Hammerhead Karoo 2 GPS computer review

Hammerhead’s Karoo 2 takes a different approach to the cycling computer concept but the results are generally excellent

Hammerhead Karoo 2
(Image: © Guy Kesteven)

Bike Perfect Verdict

Excellent color display, easy interaction and comprehensive fixed and pop up features make Karoo 2 great to use on the bike but there’s still some work to do with better off-road mapping and third-party app compatibility


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    Usefully detailed mapping

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    Excellent screen

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    Comprehensive data/functions

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    Touchscreen and button control

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    Solid connectivity

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    Secure mount

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    Garmin adaptor included

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    Regular feature/software updating


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    Separate recharge port plug

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    No smartphone control

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    No AXS sync yet

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    Training Peaks workouts only

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    No easy 'beacon' follow setting

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    Can't match OS maps off-road exploring

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    Bumper price is excessive

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Hammerhead’s latest Karoo is smaller and lighter but adds functions and features to an already comprehensive data collection and high-quality display system with easy touch or button operation. Linked training and transmission apps are still very limited though and the lack of a full smartphone interface will irritate some, there are better options for properly off-piste exploring, too. Has Hammerhead done enough with its new Karoo 2 GPS computer to compete with the best MTB GPS computers?

Hammerhead Karoo 2

Hammerhead Karoo 2, the Hammerhead out-front mount and the Garmin adapter (Image credit: Guy Kesteven)

Design and aesthetics

The Karoo 2 is smaller than the original but you still get an 82mm color screen behind toughened DragonTrail glass. The touchscreen is backed up by four physical buttons around the edge so you can still scroll and switch even in pouring rain or deep winter. Battery life is reasonable too at nine to 13 hours depending on how hard you’re working it with nav, notifications and sensors.

It's got double the storage of the original 2018 Karoo at 32GB. Dual Bluetooth chipsets and 2GB of Quad Core processor RAM mean it downloads and uploads maps and fresh software fast and has no trouble running multiple sensors including Garmin Varia traffic radar. It’s Di2 compatible and will control smart trainers in its workout mode. However, there’s currently no support for the SRAM AXS ecosystem and the only workouts it will accept are from Training Peaks and you can’t create your own either.

The base software is Android 8 but it works equally well with iOS. You can add a sim card into a carrier under the cover at the back if you don’t want to rely on piggybacking other WiFi. There’s no smartphone app though which really weirded me out at first as I normally do all my device interfacing on my phone and using a web page on a ‘proper’ computer seems oddly archaic in 2021. Because it works using a user account it does mean you can set up your Karoo 2 before it even arrives. Drag and dropping route files straight into your account for instantaneous upload is super simple or you can create your own routes within the dashboard. You can change screen layout, cell content and other display and data management operations in the unit and even create routes within the onboard navigation app if you can’t get to a computer but have got WiFi. 

Post-ride, the Karoo 2 uploads directly to Strava and other recording sites from the head unit which is ultimately faster than bouncing through a phone and it also lets you change ride names and basic settings before posting.

Hammerhead Karoo 2

Hammerhead has specced a high-quality 82mm color screen (Image credit: Guy Kesteven)

Performance and riding experience

Once you’ve adapted to its different way of doing things, the richness of the color screen and the touch or button interaction makes it really good to use. The OSM-based color mapping and pop-up prompted navigation on the high-resolution screen is also better than most GPS embedded files - especially Wahoo. It’s easy to manage any forwarded notifications you’ve opted to get and if you’re on a Strava PR hunt, the ability to monitor several live segments simultaneously is really useful for pacing. If you’re riding to the start point or back from the finish, you can flick in and out of workout and route modes without impacting your overall ride.

There are the options to set a scrolling graph display of percentage effort when power and heart rate monitors are linked up. We really like the recently introduced Climber overlay which can be set to trigger a color graded severity profile and distance to the summit of upcoming climbs which is great for gauging efforts, although the smoothed data doesn’t always pick up all the little calf-bursting kickers. 

Hammerhead Karoo 2

The metrics and OSM mapping is clear and easy to read when riding (Image credit: Guy Kesteven)

It can’t match the level of detail provided by Ordnance Survey-based systems if you’re riding off-road in the UK, however, and we had to revert to OS phone app or paper maps several times when scouting new routes. There’s no easy way to get a ‘beacon’ function for third-party tracking without tethering it through your phone either so it’s probably not the best choice for proper ‘out there' explorers. 

It uses its own unique mount design with an ‘out-front’ arm supplied but Hammerhead also includes an adaptor to make it Garmin quarter-turn mount compatible. We had no security issues with either set up even when hammering flat out on rough trails. The loose, pull-out, push-in plug for the USB-C charging port is awkward to use though and while they provide a spare we’d much rather it had a tethered plug because it's all too easy to lose. The screw-on blue, lime, orange, red and white bumpers to brighten up the all-black device are very expensive for $45 / £39, but at least the Torx screwdriver to help make the switch is included. Value is reasonable otherwise though and like most modern tech devices you can expect further free features and software roll-outs on a regular basis.

Hammerhead Karoo 2

Hammerhead offers a range of colorful bumpers as an additional purchase (Image credit: Guy Kesteven)


Screen quality, physical interfacing, comprehensive baseline data augmented with some really well presented, genuinely useful pop-up features and navigation prompts make the Karoo one of the easiest and most enjoyable to use GPS units available right now. 

The current lack of a phone control option, broader training app and SRAM AXS compatibility, third-party ‘beacon’ functions and fully detailed off-road maps will make it a no for some though. It’s still good enough to become our go-to GPS, however, and we’ll keep updating this review in line with updates to the unit itself. 

Tech Specs: Hammerhead Karoo 2

  • Price: $399 / £359
  • Connectivity: ANT+, Bluetooth, WiFi, cellular 
  • Operating system: Android 
  • Water-resistant: IPX7 
  • Dimensions: 100.6 x 60.8 x 19.3mm
  • Weight: 123g claimed, 135g actual
  • Storage: 32GB
  • Navigation: OpenStreet Map
  • Claimed battery life: 12-hours   
  • Color touchscreen: Yes
  • Screen size: 3.2in / 82mm diagonal
  • Colors: Black (standard), Bermuda, Blue, Lime, Orange, Red and White add on skins ($45 / £39)
Guy Kesteven

Guy Kesteven has been working on Bike Perfect since its launch in 2019. He started writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. He’s also penned a handful of bike-related books and he reviews MTBs over on YouTube.

Current rides: Cervelo ZFS-5, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg