Hammerhead Karoo 2 Cycling Computer Review

On your next group ride, take a look at everyone’s handlebars and the odds are pretty good that they’ve got either a Garmin or Wahoo GPS cycling computer attached to them (I’ve ridden with both — and reviewed the Wahoo ROAM and new BOLT). If a GPS cycling computer is on your shopping list, you’re probably looking at either Garmin or Wahoo. PEZ reviews Hammerhead’s challenge to Garmin and Wahoo with their Karoo 2.


Hammerhead Karoo 2 – $399

Below is a laundry list of specs (not exhaustive) for the Karoo 2. But you really should visit the Hammerhead website to check out the Karoo 2 because they’ve done a bang up job in terms of presentation — it’s definitely slick.

  • Width: 60.8 mm
    Height: 100.6 mm
    Length: 19.3 mm
  • Karoo 2 weight: 131 grams
    Hammerhead Mount weight: 36 grams
    System weight: 167 grams
  • Dragontail glass 3.2″ (diagonal) touchscreen display
    292 PPI pixel density
    480×800 portrait resolution
    16.7 million colors supported
  • Water and dustproof to IP67 rating
  • Karoo OS that is a customized Android 8 (Oreo) operating system (currently, not possible to install apps but Karoo is working on its own app store that will have cycling and sports specific apps)
  • Quad core 1.1Ghz, CPU with 2GB of RAM
  • 32GB of storage (26GB for maps)
  • Connectivity: Wi-fi, Bluetooth 4.0, ANT+, and cellular (requires SIM card)
  • GPS, GLONASS, Beidou, QZSS antennae
  • 2500 mAh battery with 12 hour battery life
  • USB-C fast charging (0% – 30% in 30 minutes, and fully charged in under 3 hours)
  • Barometer and ambient temperature sensors
  • 3-axis accelerometer, magnetometer and gyroscope
  • Beeper alerts for navigation, training, and smartphone notifications
  • Full-color, global maps, with all the details you need when riding, including POIs, elevation and roadway differentiation
  • Turn-by-turn navigation (with audio and visual cues)
  • Off-course re-routing and return home
  • Automatic upload to 3rd party services, e.g., Strava

In a nutshell, spec-wise the Karoo 2 is a fully-loaded for bear GPS cycling computer.

My Karoo 2 and mount were ever so slightly porkier than spec

What’s in the box

The boxing (and un-boxing) of the Karoo 2 is pretty slick that I’ll illustrate via a series of pictures.

Slide out (left or right) to access the Karoo 2

Pull the Karoo 2 out to access the user manual and a card with mounting and un-mounting instructions

Pull down to find all the other goodies (handlebar mount, hex wrench, Garmin quarter-turn adapter)

Inside the box is a USB-C charging cord, extra USB-C charging port cover, and lanyard

Dress up your Karoo 2

If boring black isn’t your thing and you want to stand out in the crowd a little bit, Hammerhead has Custom Color Kits to change the color of the bottom part of the unit. They’re designed to match the most widely available bike manufacturer colorways:

  • Red – Pantone 3517 C
  • Blue – Pantone 2184 C
  • Lime – Pantone 2297 C
  • Orange – Pantone 151 C
  • White – White

Hammerhead doesn’t have my trademark pink, so I went with blue since it’s my daughter’s favorite color

Hammerhead also has limited special edition kits. This one is the Moiré Mode Kit  (unfortunately, now sold out), which was debuted by the Israel Startup Nation team at this year’s Tour de France. But you can still get the Bermuda Kit, which is inspired by the pastel-painted houses of Bermuda and all proceeds go directly to the Flora Fund (founded by world-champion triathlete, Flora Duffy) to support young Bermudian athletes.

Getting started

Before you do anything with the Karoo 2 (other than charge it up), you should create your Hammerhead account so you can do some stuff on the dashboard rather than the unit itself (although almost everything you need/want to do, you can do on the Karoo 2).  Again, I’ll illustrate via pictures.

Go here to create your account

Home page after you’ve created your account

All your rides are here

What you see if you click on a ride

You can create or import routes here. I just copied and pasted the URLs from my Ride with GPS routes. Easy peasy.

You can edit your route on the Hammerhead dashboard

If you use TrainingPeaks (I don’t), Hammerhead can connect and integrate your workouts with the Karoo 2

As of this writing, you can connect Strava, Ride with GPS, TrainingPeaks, Komoot, and Xert (and your Karoo 2 can automatically upload to connected accounts)

Setting up a Profile

There’s a lot you can do with the Karoo 2 and I’m not going to cover everything in this review (I’m sure PEZ readers know a certain someone on the web who is the acknowledged master of that and I’m not here to challenge or compete). But I’ll try cover enough of the “basics” to give you an idea of how to navigate the unit to set up the features you want.

The most important thing to remember is that the Karoo 2 is basically a smartphone in the way it operates. So everything you do on it is via touchscreen … albeit a much smaller touchscreen than my iPhone 11. And the touchscreen is relatively sensitive. If you suffer from “fat fingers” on a modern smartphone, you might find yourself (as I did) having to do “do overs” tapping on icons and using the small virtual QWERTY keyboard.  As much as possible, I’ll let pictures do most of the talking.


After you turn the Karoo 2 on (lower left side button), it will warm up and cycle through to the Profiles screen

Hammerhead provides a handful of already configured Profiles (the screens you see while riding). You can use the screen layouts as-is or change them to your liking (based on the templates Hammerhead provides). Regardless, you’ll have to configure the data fields to display the information you want to see while riding.

Or you can create a custom Profile(s), which is what I did for my everyday riding: JAFR (which is a play on the term JAFO from the 80s movie Blue Thunder). I’ll walk you through via pictures.

Left: From the home screen, tap on the menu button
Middle: Select Profiles
Right: Select + to add a new Profile

Left: Enter the name for your new Profile
Middle: Save your new Profile
Right: If you want more than one data field, edit the layout of your new Profile

Left: Pick the Data Layout you want (rectangle) and then navigate to it (circle)
Middle: Pick the data field you want to edit, which will take you to your choices
Right: Pick the data field you want to display

Left: Pick the data you want displayed and then navigate back to the Data Layout
Right: Change all the data fields in your Profile to display what you want and where on the screen (this is my finished JAFR Profile)

But wait, there’s more!

You can have multiple screens in any Profile. For navigating, I wanted a dedicated  map screen. It’s a lot like creating a custom Profile but it’s within your Profile. So you start as you would for creating a custom Profile:

  • From the home screen go to the menu (tap on the bottom left light blue button)
  • Tap on Profiles
  • Tap on the Profile you want to edit, which takes you to the Edit Layout screen

Left: Tap on Edit Layout
Middle: Swipe left
Right: Chose the new screen type (rectangle) and then add it (circle)

Left: Choose the screen layout (rectangle) and then save it (circle)
Right: My finished map screen

I have four screens (my riding data, map, power, and climbing) for my JAFR profile (I don’t know if there’s a limit on the number of screens, but if I go to Edit Layout I have the option of creating another screen). While riding, I can swipe left or right to move from screen to screen.


Top – My main riding data screen. Bottom (left-to-right) – My swipe screens: map, power, climbing.

You’ll notice the data screen is white-on-black (what Hammerhead calls “In-Ride Dark Mode”), which is the default display. My eyes find this easier to read. You can switch it to black-on-white but be aware that this will likely consume more battery power (one of the reasons I use dark mode on my phone).

Another thing I like about the Karoo 2 is that riding time, battery level, and time of day are displayed along the top — so data fields I don’t need that would otherwise take up screen real estate.


I subsequently modified my JAFR power screen to use the Graphical Data Fields feature to display power. Instead of just my power output number, the Circular Zone display (bottom data field) color codes my power output zone based on my FTP.


Mounting the Karoo 2

If you’re used to the quarter-turn Garmin or Wahoo way of doing things, the Karoo 2 is different. You slide it on. And you twist to unlock it and then slide it off.

One look and it’s obvious the Karoo 2 mount is different than either Garmin or Wahoo

Slide the Karoo 2 onto the mount and it locks onto the tab (red dashed line circle)

Twist the Karoo 2 clockwise (until you hear/feel two clicks), then slide it off the mount


The Karoo 2 is very low profile #aero #marginalgains

But (wisely IMHO) Hammerhead gives you the option of being able to use the Karoo 2 on a Garmin mount via an adapter. Obviously handy if you’re coming from the Garmin universe and already have a Garmin mount on your bike.

Just slot in the adapter and the Karoo 2 is Garmin quarter-turn ready

I’m not a fan of handlebar mounts (just from an aesthetic perspective) and use a (no name brand made in China from Amazon) mount that attaches to the stem faceplate. In my case, I swapped out the Wahoo “puck” for my ROAM to a Garmin puck to mount the Karoo 2.

The Garmin adapter adds a few grams

The lanyard provides some additional security should the Karoo 2 ever become disconnected from the mount (like in a crash), as well as a bit of anti-theft protection


Once you have the Karoo 2 set up to your liking and decided whether to use the Hammerhead or Garmin mount, you’re ready to ride. It’s pretty easy peasy and not unlike most other cycling computers.

Left-to-right: Turn on the Karoo 2 with the lower left button. Choose the Profile you want to use. Tap the yellow box in the lower right part of the screen to start your ride. You’re ready to ride! [NOTE: You can also start a ride by pressing the lower right button.]

Assuming you have Auto-Pause turned on (and you can set the threshold speed for when the unit pauses), the Karoo 2 will pause recording your ride whenever you stop. If you have Sleep turned on, the screen will go to sleep after a prescribed period of time (that you can choose).


You can also turn the screen off manually by holding the power button down for ~2 seconds and you’ll be given the option of turning the Karoo 2 off or turning the screen off. To turn the screen back on, just press on the power button.

And here’s how you end a ride:

Left-to-right: Tap on pause (the yellow arrow on the left is to record laps). [NOTE: You can also pause by pressing the lower right button.] Tap on the yellow box. Tap on the yellow box again. Tap on the blue checkmark box to save your ride.

After your ride is saved, you can view your ride data.

Left-to-right: Ride data summary. Speed details. Climbing details.

Left-to-right: Power details. Cadence details. HR details.

Hammerhead will upload the ride to your connected apps. But it only does it via WiFi. So your Karoo 2 needs to be connected to an authorized network.


You can have text messages, calls, voice mail, and notifications from other apps pushed from your phone to the Karoo 2 (I have mine set for just text messages)

Maps and navigation

For me (differences in how you set up and operate the unit aside) basic riding with a GPS bicycle computer is pretty much the same no matter which manufacturer. Where there are real differences are in maps and navigation. IMHO, the Hammerhead Karoo 2 is outstanding thanks to its screen real estate, the brightness/clarity/resolution of the screen (for all intents and purposes, it’s on par with modern smartphones), and its use of colors.

To begin, Hammerhead gives you access to a global map set and generous storage to download the regions you need to the Karoo 2. And the maps are detailed with street names.

I downloaded the DMV (DC, Maryland, Virginia) for my local riding and have plenty of available storage to load more maps for any out of the area riding (like when we go to Hilton Head, SC)

I’ll let pictures (with short descriptions) do most of the talking and they should give you a pretty good idea of what the Karoo 2 maps look like and how navigation works.

Loading a route (left-to-right): Tap on Route on the map screen. Choose a route (from routes you have stored on your Hammerhead account). Tap on the blue check mark box to load the route. Tap on the yellow arrow box to start your ride. [NOTE: Since I’m not at the ride start, the red line on the map is the Karoo 2 routing me there.]

Follow the yellow brick road. You know you’re on route if the road ahead of you is yellow. The box at the bottom let’s you know how far to the next turn and which way to turn.

You don’t have to be on the map screen to see navigational cues

When you’re off course, the route will be red and designed to bring you back on course

Re-routing even if you’re not on the map screen (when you get closer to the turn, the directional cue box is larger and more detailed to get your attention)

Yellow to keep you on route. Red to get you back to the route.

In a nutshell, I was very much impressed with the Karoo 2’s navigation. The maps are easy to see/read (BTW, you can pinch zoom in and out on the maps — again, the Karoo 2 is essentially the equivalent of a smartphone without the phone part). The directional cues have “pop” to catch your attention (there’s also an audio alert that you can turn on or off). The use of color (yellow for on route and red for off) makes it visually easy to figure out if you’re where you should be — even if you’re not on the map screen. Plus the use of color on maps makes them easier to read/navigate, for example (these aren’t all the colors):

  • Blue for water (this is kind of obvious)
  • Green for parks and other greenspace areas (also obvious)
  • Green/white for bike trails
  • Darker yellow for more major roads

If you do a 2-finger swipe up on a map, it changes from (left) 2D view to (right) 3D view (2-finger swipe down to go back to 2D). Pretty cool, eh?

I’m happy to report I haven’t experienced any “lag” when turns were in close succession to each other (usually in a more dense urban environment). I’ve had this happen with both Garmin and Wahoo. The navigational cue will get “stuck” on the last turn and not show the next turn. And it can take a while to catch back up to where it’s supposed to be.

I also haven’t experienced any “wrong turn” glitches (again, something I’ve had happen with both Garmin and Wahoo) where the navigational turn cue will be different than what the route on the map shows (and the map is correct).

The only “glitch” I’ve experienced is this:

Interesting re-routing. Going straight and turning left at the next intersection would put me back on the route faster and more directly.

It’s not that the re-routing was “wrong.” Just not how I would’ve re-routed based on local knowledge. FWIW, I have similar experiences using Google Maps when driving. Sometimes the human is just smarter than the algorithm.

It’s also interesting to compare how different AI choses to re-route you. I was riding with a friend where we both had the same route loaded. I intentionally took us off the route. His bike computer (Wahoo BOLT) had a very different re-route than my Hammerhead Karoo 2. When we got to the proverbial fork in the road, his BOLT wanted us to go left and my Karoo 2 wanted us to go right (we went right). Both would’ve gotten us back on course, but going left would’ve intersected the route at an earlier point.

Finally, even when I don’t have a route loaded, I find myself using the map screen more often than not just because it’s more engaging. That’s a testament to the designers/developers at Hammerhead. [NOTE: Hammerhead’s claimed 12 hour battery life is probably a best case scenario using the data screen in dark mode; using the map screen will likely use up the battery faster.]

Side buttons

Other than turning my Karoo 2 on and off, I haven’t really used them — but you can use the side buttons to do many of the things you do via the touchscreen (but not all — such as keyboard input). Their use is largely intended for when the touchscreen isn’t practical/feasible (such as wearing winter gloves or riding in the rain). Hammerhead has a good article on using them.

Honestly, it reminds me of what I didn’t like about operating my old Garmin via the side buttons

For the mountain goats

A really cool feature on the Karoo 2 is CLIMBER. Per Hammerhead:

Hammerhead has been working closely with some of the greatest climbers in the sport, Chris Froome and Michael Woods, as well as the ISN Team to develop CLIMBER: a detailed and analytical look at upcoming elevation. Designed to help riders see exactly what lies ahead, CLIMBER provides ascent-specific insights so riders at every level of the sport can climb more intelligently and effectively.

[NOTE: CLIMBER only works if your have a route loaded. Interestingly (as I found out), if you ride off-route, it will show you any climbs to get you back on route.]

CLIMBER allows you to pick what type of climbs will pop up on the Karoo 2. I chose medium and large climbs.

When you approach a climb, a “tray” pops up with the climb profile, gradient info, and how much climbing (length and elevation) to go to the top

[NOTE: If you don’t want see any trays that pop up (such as directional cues or phone notifications) taking up screen real estate, just swipe down and they’ll disappear. Swipe up from the bottom of the screen to make them re-appear. Remember, the Karoo 2 operates much like a smartphone.]

You can see where you are on the climb (red arrow)

Xert app

Another cool feature on the Karoo 2 is that it has an app store (just like a smartphone). Right now, the only app available is the Xert app (Hammerhead promises more cycling and sports specific apps sometime in the future). Loading it gives you access to the Xert app on the Karoo 2 in the same way as on your smartphone.

Left-to-right: Tap on the App Store. Tap on the Xert app. Tap on the blue box to download. Voila! (If you want to delete the app, tap on the red-ish box with the trash can.)

[NOTE: Hammerhead doesn’t officially support doing so, but since the Karoo 2 uses the Andoid 8 Oreo OS, it’s possible to side load apps if you’re tech savvy enough and inclined to do so.]

Log into your Xert account and you can access the app on the Karoo 2 instead of having to use your phone (please don’t laugh at my stats … technically, I’m a geezer!)

Additionally, for those of us who use Xert for training (I’m not really training for anything but use Xert to monitor my fitness level), loading the app allows you to display MPA (Maximal Power Available) or XSS (Xert Strain Score) data on the Karoo 2.

In my case, I wanted to have MPA displayed on my power data screen to compare actual power vs MPA to know whether I can push myself to achieve a Xert breakthrough effort (essentially when actual power exceeds MPA which results in Xert re-calculating a new fitness signature, i.e., increased threshold power)

I haven’t tried yet, but with the Xert app on the Karoo 2, I should be able to load a Xert workout and use that to guide my effort on a ride. And since the Karoo 2 is both ANT+ and Bluetooth, I should be able to connect it to my KICKR and use it to control an indoor workout (instead of using my iPhone or iPad). Definitely on my “to do” list when the indoor riding season rolls around.

Almost perfect, but …

For my riding, the Hammerhead Karoo 2 is pretty close to perfect. But there are still a few things I would wish for (if the engineers/developers/designers at Hammerhead are listening):

  • Ride upload via Bluetooth to my phone (I don’t know if this could be done to the Hammerhead Dashboard directly or if it would require developing a phone app)
  • Color-coding the display of power, heart rate, and training zones (either the numbers or the background of the data field) without having to use the graphical display feature, which is cool but takes up a lot of screen real estate
  • An indicator to know if you’re riding above or below your current average speed for the ride without having to have an average speed data field

I have to believe doing these would be relatively easy (but I’m not a coder) given the Karoo 2 tech specs and the fact that it’s using the Android 8 Oreo operating system.

And if I had one “concern,” it’s that (so far) my experience with the battery isn’t Hammerhead’s claimed 12 hours. It’s more like 8-9 hours. Of course, that could be because I’m enamored with the map screen. And the fact that I’ve had the unit turned on a lot learning, setting it up, and taking pictures for this review, i.e., not riding. That said, 8-9 hours is more than enough battery life for any one ride I would do. And I wouldn’t be surprised if I get more like 10 hours once I’m just riding with the Karoo 2, i.e., not fooling around with it.

On a semi-related note, the Battery Save feature (it’s in Settings) can extend battery life but at a “price.” It turns the screen off after ~30-40 seconds of riding (you can turn it back on by pressing the power button). The screen will come back on after a full stop, but turn off again after ~30-40 seconds. When you start rolling again, the screen will turn back on (but off again after ~30-40 seconds). So not terribly useful for actual riding if you need to see the info displayed on your screen. But if you wanted to do a ride by “feel” instead of by the “numbers,” you could use Battery Save to not display your ride data but still be able to record and download your ride afterwards.

Hammerhead HRM – $64


If you’re in the market for a heart rate monitor and want to be matchy-matchy with your Karoo 2, Hammerhead has an HRM. Like other chest strap HRMs, it’s a strap with a removal pod (that uses a ubiquitous CR2032 battery). It’s both ANT+ and Bluetooth so you shouldn’t have any problems getting it to connect to any device or app (like Zwift) you’re using. And it’s a little bit different than most other chest strap HRMs that use polymer electrodes: “The Hammerhead Heart Rate Monitor uses an all-fabric strap design in which silver fibers are woven into the fabric electrodes for highly sensitive and accurate ECG signal detection even on users with low skin impedance.”

I can attest that the electrodes are softer and a little more comfortable against my skin. #marginalgains

I can’t say how accurate the Hammerhead HRM is, but I can provide this anecdotal data point. I use the Elite HRV app in the morning to measure my heart rate variability. My HRM that has polymer electrodes always seems to have a lot of signal artifacts (the app corrects as many of them as possible). At least so far, the Hammerhead HRM with fabric electrodes has better signal quality and fewer artifacts.

Giving Garmin and Wahoo a run (or is that ride?) for their money

I know I haven’t covered everything, but that’s because the Karoo 2 has so many things it can do and I haven’t used them yet (and some of them I may never use).  For example (just a few):

  • Creating a route on the Karoo 2
  • Karoo 2’s Return Home feature
  • Workout integration with TrainingPeaks
  • Using the Karoo 2 to guide your workouts
  • Adding a SIM card for cellular connection

But hopefully I’ve given you enough of a taste of what the Hammerhead Karoo 2 can do to demonstrate its capabilities and pique your interest.

IMHO, Hammerhead has a winner on their hands. Price-wise, the Karoo 2 is in the same category as the Garmin Edge 830 and Wahoo ROAM — so those are logical points of comparison for making a buying decision. [Interestingly, Hammerhead doesn’t sell separate speed or cadence sensors. If you have a crankarm-based power meter, you shouldn’t need a cadence sensor. And you could rely on GPS-only for speed. But if you want/need either of those sensors, you’ll have to get them from a third party … such as Garmin or Wahoo.] Feature – and performance-wise, the Karoo 2 can certainly hold its own with the market leaders.

If you’re in the market for a GPS bicycle computer and looking to spend upwards of $400, the Hammerhead Karoo 2 should be in the mix.

Time will tell if the Hammerhead Karoo 2 builds a following. Four-time Tour de France winner (as well winner of the Giro d’Italia and La Vuelta) Chris Froome thinks highly enough of Hammerhead to have invested in the company, as well as becoming a member of the company’s advisory board. Justin Williams, founder of L39ION of Los Angeles, is also on the advisory board. Those are pretty good names for helping to build a following.

When I reviewed the Wahoo ROAM, I said this: “Ultimately, what’s most important is that Wahoo has come up with a worthy product to give consumers more choice in the marketplace.”  The exact same can be said of the Hammerhead Karoo 2. But it’s more than just marketplace competition by giving consumers another GPS bicycle computer to consider. Because it’s a smartphone pretending to be a bicycle computer, the Karoo 2 is more akin to a disruptor in the marketplace with the potential to be a game changer. It’s that kind of competition that can give Garmin and Wahoo a run (or is that ride?) for their money.

My life behind bars with the Karoo 2 (if you’re curious, my headset top cap — and matching bar end caps that you can’t really see — is the Illuminati from KustomCaps)

Note: If you have other experiences with gear or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews or a slap in the head if you feel the need!

PezCycling News and the author ask that you contact the manufacturers before using any products you see here. Only the manufacturer can provide accurate and complete information on proper/safe use, handling, maintenance, and/or installation of products as well as any conditional information or product limitations.

Like PEZ? Why not subscribe to our weekly newsletter to receive updates and reminders on what’s cool in road cycling?