Hammerhead Karoo 3 review: the best GPS for SRAM AXS owners – but it's a different story for Di2

Hammerhead’s policy of supplying a steady stream of updates means the Karoo is always developing and this third-generation bike computer gets a significant overhaul. It includes a new case, improved performance and battery life, simplified and effective routing, and a great screen.

If you're looking for a GPS that has good battery life, is easy to use and works better than its rivals with the SRAM AXS Ecosystem, look no further. If you're an existing Karoo user, this new version offers just enough to justify the upgrade.

It's also less expensive compared to its premium rivals from Garmin and Wahoo.

Hammerhead’s original Karoo offered plenty to rival the best bike computers from more established brands, with a great screen and a wealth of data acquisition.

The downside was limited battery life compared to its rivals and sluggish startup.

Hammerhead Karoo 3 specs and details

This latest version of the Karoo brings the first complete hardware overall in the computer’s history.

RAM has doubled to 4GB, and the processor has nearly doubled in speed to 2Ghz from 1.1 – both intended to speed up the user experience. The storage has also doubled to 64GB, offering more map and route space.

Compared to premium rivals, the storage matches the latest Garmin Edge 1050, although Garmin remains tight-lipped around the 1050’s other specifications (albeit, Ashley Quinlan found it very responsive in his review).

It’s also a match for the Wahoo Elemnt Ace in the storage stakes, but similarly, Wahoo also hasn’t released any specifications on the Ace's processor or RAM.

The case has changed from the wide-front, narrow-rear shape of the original, flipping it to make it narrower at the front. It gives the unit a sleeker look compared to the previous generation.

The screen is brighter than the previous iteration and gets Corning Gorilla Glass to improve both visibility and toughness. It’s competitive with both the Garmin Edge 1050 and Wahoo Elemnt Ace for overall visibility, albeit the 1050 is brighter and delivers more contrast.

The battery has increased in size to 3,200mAh from 2,800, delivering a claimed 15 hours' life, up to 35+ hours if you turn on the new battery save mode. A dedicated power button has been added to the case (before, the Karoo was switched on and off by a multi-use button on its left flank).

The case now has five buttons in total, with the power button on the base and twin buttons on its flanks. These, alongside the touchscreen, mean there are lots of ways to interact with the unit.

Hammerhead has removed the SIM card slot (claiming few people used it) and added dual-band GPS/GPNSS for quicker locating. Hammerhead says the audio-alert volume has increased too.

Even with all these hardware changes, the device is lighter than the previous generation, weighing in at 118g (down from 132g).

Software-wise, Hammerhead says battery management system improvements should deliver a 30 per cent boost to battery life.

The core of the system now operates on Android 12 (64-bit), where the original was Android 8 (32-bit). You're unlikely to notice this because the user interface remains much the same as the Karoo 2, with a few added widgets.

What’s in the box?

• Lanyard
• USB-C charging cable
• New HMS mount (with adjustable positioning)
• A Garmin quarter-turn to Karoo HMS mount adaptor
• A hex key for the mount

Aside from the GPS unit, Hammerhead provides everything you need to get up and running quickly. The V-shaped HMS (Hammerhead mounting system) mount is dog-legged, so when mounted on your bar it centres the unit ahead of your stem, like most standard out-front mounts.

The slide-in lock of the HMS is secure and creates a lower-profile fitment than Garmin and Wahoo’s take on the quarter-turn mount (albeit Wahoo employs its partially shrouded design).

That said, Hammerhead obviously knows the prevalence and popularity of Garmin’s quarter-turn design on aftermarket mounts. To address this, it includes a slide-in converter for the base of the Karoo that makes the unit Garmin-mount compatible.

A lanyard to save the head unit in the event of an accidental ejection is useful (Garmin and Wahoo also supply these).

The one-metre long braided USB-C charging cable is a nice touch too – braided cables are generally considered to be more resistant to bend damage.

Hammerhead Karoo 3 user experience

Powering up is simple with a press of the base button, and compared to the previous generation, it's quicker to start up (although only by around a second).

This assumes the unit isn’t updating, though – given Hammerhead pushes a regular stream of updates that automatically download whenever you're connected to Wi-Fi, times vary more than they otherwise might.

Compared to Garmin, which releases updates much less frequently (around two to four times a year), Hammerhead has updates rolling out on a fortnightly basis.

On one hand, it’s great that Hammerhead is constantly working to make the performance better.

On the other, it can mean a wait as the system updates on turning on. I’d recommend turning the Karoo on while you’re having your pre-ride coffee rather than when you get on your bike.

For example, as I was completing almost a year of testing the Karoo, Hammerhead rolled out a significant new battery save mode, which means my findings over the last year of on average 12–13-hour battery life could now be expected to increase to 30 hours or longer thanks to the series of smart save modes available.

The save mode turns off your screen automatically and only switches on when you need it – when a turn is upcoming on your navigation for example, or when the climb function is about to kick in at the foot of a hill.

The default is for the screen to remain on for 35 seconds and it caps the screen brightness at 45 per cent. You can assign the battery save modes to ride profiles individually, resulting in different settings for road, mountain, gravel and any of the individual modes you’ve created.

You can even turn down the processing speed using the advanced battery-saver settings in the menu.

I’ve tried it with the default settings and increased the battery life to just over 25 hours with some navigation. That improves to 30.5 hours using the Karoo to solely record rides (with SRAM AXS, a heart rate monitor and a power meter connected).

The screen is bright, certainly an improvement on the previous generation and a broad match for Garmin’s latest screens (albeit, as mentioned, the 1050’s panel is a little bolder).

The touch sensitivity is excellent – gloves with touch-tips work well – although a few of my thicker winter gloves proved troublesome.

I like that the screen can be switched from bright (white background) to dark (black background) with a downward sweep of the screen and tapping the option. I settled on using the bright mode on the road and the dark mode for off-road duties in the woods or when the light dropped significantly.

The display options on the swipe-down tab also include a manual screen-brightness adjustment and a rain lock, which locks the touchscreen and prevents accidental activation when the heavens open.

If you have the latest SRAM Red AXS levers, you can use the Karoo to assign the hidden buttons on the side of the hood to perform tasks. I’ve currently got the left-hand button set up to shift the front derailleur and the right-hand button set to switch between Karoo data screens.

The distance and elevation data is on a par with the Garmin Edge 840 I tested it alongside, although the Karoo needs to be connected to your phone (and the Hammerhead app) for elevation calibration.

While the Karoo has a barometric altimeter, Hammerhead says this can be affected by weather conditions. The calibration app helps to correct any errors by adding a baseline elevation based on your location.

What irks me, though, is every time I launch the Karoo, it defaults to audible alerts, which are quite intrusive.

Riding on a beautiful, crisp morning and being met by a series of loud beeps is a pain, especially if it’s notifying you of phone alerts – it was an almost constant chorus until I swiped down into the settings and shut it up. Ideally, I’d want a setting to silence the Karoo by default.

New Hammerhead companion app

At first glance, the companion Hammerhead app looks somewhat vanilla, merely showing the information pertaining to your Karoo, such as the software version, serial number, and your Hammerhead registration number linking your desktop account to the unit.

It is, however, doing quite a lot more behind the scenes. Firstly, it now syncs with your phone to transmit live tracking information on your rides so you can share your location with selected contacts. This was possible in previous generations, but only if you inserted a SIM card into the unit.

It’s a better system, because now that information is charged to your phone plan, just like units from Garmin and Wahoo. The second important extra the app facilitates is a simple-to-use and impressive routing system.

You can use pre-configured routes created on the Hammerhead desktop dashboard or any number of third-party platforms – support is there for Komoot, Ride with GPS, TrainingPeaks and Strava.

Strava’s recent decision to limit third-party app access may have implications for Hammerhead, though.

When asked about it, Hammerhead responded: “We do not have an official statement at this time, but we are aware of this and are in the process of evaluating how these changes impact Hammerhead riders and any changes we need to make with our Strava integrations moving forward."

For creating a route on the fly, instead of navigating through clunky searches and frustrating results, you simply open the map application of your choice on your phone, drop a pin and share it via the Hammerhead app to your Karoo.

Then, depending if you’re using a road, mountain or gravel ride profile, it’ll create a route to your destination to suit. It works very well; I’ve used it mainly with Apple and Google Maps for road rides and it (thankfully) chose smaller roads by default rather than sending me to major ones.

It’s also good on gravel, but it's more reliant on the quality of the mapping covering the area. I have had occasional strange choices mid-route where the base map is flawed, such as directing me from a byway or bridleway onto a footpath. It even tried to direct me onto an off-limits military road on Salisbury Plain.

That said, the Karoo intelligently re-routes rather than the miles of ‘do a U-turn’ instructions I’ve had from some computers.

Garmin has recently rolled out a similar system through the Garmin Connect app for its newer-generation computers, while Wahoo’s Elemnt Ace also has the pin-drop navigation function.

I think the Hammerhead’s app is the most polished overall (a view shared by Ashley), but all three major GPS players have taken big leaps in making on-the-fly navigation finally a user-friendly experience.

Climb assistant

Hammerhead set the standard with its predictive climb function – it was the first among the big players to introduce the tech.

This works brilliantly; approach the foot of a climb and it automatically switches to a gradient profile with rolling information covering the gradient angle, length of the climb, remaining distance and remaining gradient.

It’s easy to understand and doesn’t suffer from too much in the way of lag – something I have found on occasion with Garmin’s equivalent.

It’s a very useful function for managing your efforts, especially if your data screen is configured with power and heart rate data in the top quadrant and the gradient graph at the base.

Being able to know accurately when the crest of an unknown climb is near so you can give it your all without blowing up is a boon (especially if you’re working with limited climbing resources, like me).

Creating profiles

The standard profiles of road, gravel and indoor are all well and good, but the Karoo enables you to create as many fresh profiles as you like.

Setting a profile to a particular bike is an excellent function, especially if you have more than one, because you can assign sensors such as power, AXS shifting, radars and even specific heart rate monitors to the profile. Essentially, it automatically finds and connects to those sensors when you ride.

Sadly, it doesn’t sync with SRAM’s AXS bike garage, so there is some repetition to be done on setup – Hammerhead is a sub-company of the SRAM group, so I asked about this and the brand says it's looking into it for later software updates.

Best for SRAM, but not for Shimano

The way in which the Karoo syncs with SRAM is excellent. It automatically pulls in all your sensors across your bikes from your SRAM AXS account (which you can then select and attach to profiles).

It’d make sense for Hammerhead to introduce an interface with SRAM’s Flight Attendant, providing suspension control on the fly rather than having to pull out your phone. It could be a game changer for SRAM and Hammerhead, but it’s not yet a feature.

When I asked, the official response was: “The team is evaluating all SRAM and AXS integrations. Karoo will integrate with Flight Attendant, but we do not have a timeline to share right now.”

The news isn’t so good for Shimano users, given Shimano restricted the information it will share with the Hammerhead Karoo in 2022.

So, unlike on a Garmin where you can see the gear you are currently in, on the Karoo there’s no such data available. Hammerhead says it has approached Shimano to open this data sharing up, but nothing has happened as of yet.

Hammerhead says Di2 users are a large part of its user base, and it's a shame those users won’t get the same experience as they might through a Garmin.

There are aftermarket workarounds (the Ki2 app is well-regarded), but I hope for an agreement to be made to restore the functionality Karoo users once enjoyed with Shimano.

No onboard training programmes

Unlike Garmin and Wahoo’s software, which comes with plenty of training sessions and plans, the Karoo doesn’t.

Instead, it relies on you having a TrainingPeaks, TrainerRoad or Strava account to create workouts, which will upload from the desktop dashboard to the Karoo (these incur a subscription fee, of course).

You can also upload Fit or ZWO files directly, but it’s up to you (or your coach) to design them.

Hammerhead web dashboard

The Hammerhead desktop dashboard is easy to navigate and use, with your ride history, library of routes, workouts and accounts linked to the Karoo all displayed.

You can use the dashboard to import routes, and workouts, and sync your accounts from Strava, Suunto, SRAM AXS Web, Ride with GPS, TrainingPeaks, TrainerRoad, Komoot, Xert and Sentiero.

Compared to the masses of native options and information you’ll find on Garmin Connect, it's a little spartan.

It’s also worth noting that Hammerhead currently only makes the bike-specific Karoo, whereas Garmin has a wide range of health and fitness wearables, peripherals and GPS products that can all be synced with the Garmin Connect system.

Hammerhead Karoo 3 bottom line

Overall, the Karoo is a solid competitor for Garmin and Wahoo’s premium offerings.

Although expensive at £449.99 / $474.99 / €499.99, it’s less expensive than the premium Garmin Edge 1050 at £650 / $700 / €700. The new Wahoo Elemnt Ace is £550 / $599.99 / €599.99, which makes the Karoo £200 and £100 cheaper respectively.

The hardware has proven robust in all weather, and battery life is more than ample, especially after the recent battery-saving update. The cost includes all the extras you need to get straight out on the road, too.

I like that the Karoo is continually being updated by Hammerhead and it hasn’t ever felt ‘unfinished’ as a result. Even if that can be a little annoying when you power up the Karoo and have to wait a minute or two for it to update, it's a good thing.

If you’re a SRAM AXS user, the Karoo offers the best and simplest access to the data on tap. Its seamless integration with AXS is impressive and will only improve further as Hammerhead rolls out updates.

For Shimano users, the Karoo isn’t as impressive. It gives Di2 owners less data – not good when you’ve invested in a premium drivetrain.

For simply riding, recording and navigation, the Karoo impresses, and I prefer the route information (especially the climb functionality) to Garmin’s very similar system.

All in, Garmin’s broad ecosystem continues to make Edge units a compelling sell, although the Hammerhead Karoo v3 is a viable, slightly better-value, alternative.

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