Hammerhead Heart Rate Monitor review: The perfect companion for your Karoo 2 bike computer

Hammerhead Heart Rate Monitor review in a sentence: A keenly-priced Karoo 2 accessory for better heart rate data that also works well with other devices (e.g. smartphones). 

The Hammerhead Heart Rate Monitor is just one of many such accessories for keeping tabs on your ticker when you’re out on your bike or doing some other kind of workout. In fact, the range of best heart rate monitor models is growing all the time. However, the Hammerhead Heart Rate Monitor has been designed to complement the Hammerhead Karoo 2 cycling computer.

So, if you’ve got one of those premium head units (as featured in our best cycling computer guide), the affordable cost of this supplementary gadget to your kit arsenal seems like a sensible idea. The Hammerhead Heart Rate Monitor works with other devices, too, including smartphones, which somewhat broadens its appeal.

I first got to experience the Hammerhead Karoo 2 GPS cycling computer a couple of years ago, and it turned out to be one of the most impressive head units out there, easily holding its own up against products from Garmin and Wahoo. Since then, there have been updates, with the most recent adding lots of extra features and functionality.

Hammerhead Heart Rate Monitor review: Price and availability

The Hammerhead Heart Rate Monitor is available now and costs £54 in the UK, with a price tag of around $64 in the US and AU $64 in Australia. It can be purchased from the usual array of online outlets or directly from Hammerhead too. At the time of writing, Hammerhead is also offering special offers on coloured cases for the Hammerhead Karoo 2 if you want to buy the pair as a bundle. The Hammerhead Karoo 2, which the HRM works in tandem with, is available for $399 / £359 / AU$639.

Hammerhead Heart Rate Monitor review: What is it?

The Hammerhead Heart Rate Monitor, or HRM, is just that; a device that is comprised of an adjustable elastic strap, which is fully adjustable and washable too, mated to a small plastic pod unit. The pod attaches to the strap via a couple of popper studs, while the strap itself can be adjusted between 711 and 1219mm / 28” and 48”, so take note if your chest is bulkier than that. It’s easy to put on, with a side-mounted strap connector that can be hooked up without the need for any assistance.

In terms of weight, the pod is just 15 grams while the strap is 28 grams, so even combining the two numbers, you’re looking at something that’s pretty unobtrusive to wear. It’s designed to fit snugly around your torso, with the plastic pod being placed over the central chest/heart area. While it’s aimed primarily at cyclists with the Hammerhead Karoo 2 head unit, the big benefit of this HRM is that it’s a little better for use in the gym if you’re working out with the likes of kettlebells. This is especially so compared to fitness watches because it’s well out of the way and doesn’t impede wrist movements.

Hammerhead Heart Rate Monitor review: Is it any good?

I’ve found the Hammerhead Heart Rate Monitor very easy to use once it’s paired with my Hammerhead Karoo 2 head unit. The great thing is there’s not all that much effort involved in getting it set up. Simply power up the Karoo 2, attach the pod to the strap and hook it around your torso, so the rubber electrodes make contact. 

Once it’s in place, the pod wakes up and gets listed in the Karoo 2 devices menu, which allows it to be paired to the unit. Once you’ve done that, you’re free to start monitoring in whichever capacity you want to collect the date, ie; a cycle ride or workout down at the gym. It'll work seamlessly with your preferred apps, too, such as Strava.

I’ve found the Hammerhead Heart Rate Monitor to be very good out on the bike, but it’s also pretty good for cardio work at the gym. You can actually take your Karoo 2 with you for your workout, but I’m quite keen on the Hammerhead app, which is just as user-friendly as the bike computer. This is always a bonus if you’re frequently faced with sweaty scenarios where you need to keep contact with handheld devices to a minimum. 

The other bonus with the Hammerhead HRM is that it’s strapped on, out of sight, and you can almost forget you’re wearing it. I also like the way the strap can be washed easily enough, so you don’t end up with another smelly fitness accessory lying around in your gym bag.

Hammerhead Heart Rate Monitor review: Performance

The Hammerhead Heart Rate Monitor looks deceptively simple, but it’s smarter than I expected, which is due in part to the electrode material that is a blend of fabric and woven silver. This seems to make it reassuringly accurate when compared to something like my Coros Apex 2 Pro multisport watch. There’s also the capacity for producing RR intervals, and this, along with the ability to pair two Bluetooth devices and as many ANT+ receivers as you like, makes it wonderfully flexible.

Hammerhead also claims the unit is waterproof down to 30 metres, which I’ve yet to try, but that’s an impressive enough figure for most everyday needs. There’s also a similarly impressive battery life of over 900 hours, and you can easily replace the CR2032 3-volt battery inside the pod using a coin to undo the casing.

Hammerhead Heart Rate Monitor review: Verdict

The Hammerhead Heart Rate Monitor is an obvious choice if you’re looking for a quality HRM to supplement your Hammerhead Karoo 2. There’s not a whole lot to it, but the asking price seems reasonable enough, especially considering how well it works. It’s easy to get set up, too, and the battery life is excellent. While the Hammerhead Heart Rate Monitor has plenty of rivals worth considering, a few of which we’ve outlined below, it makes total sense if you’re keen to keep everything in the Hammerhead family.

Hammerhead Heart Rate Monitor: Also consider

If you’re serious about cycling and monitoring your workout stats, then the Hammerhead Heart Rate Monitor is well worth getting, especially if you already own the Hammerhead Karoo 2. You can get them as a bundle, too, if you’re new to the Karoo brand.

However, there are other options on the market. Lookout for the super-popular Garmin HRM-Pro if you’re keener on running and the gym, as it works in tandem with Garmin watches, provides copious amounts of data and works using Bluetooth and ANT+.

Similarly, the Polar H10 heart rate monitor is another popular option, notable for its excellent levels of accuracy and easy pairing with the likes of fitness apps, sports and smartwatches. It also uses Bluetooth and ANT+ connectivity, plus there’s the ability to hook it up to your watch and your turbo trainer if the weather’s too bad to head outside for a ride.

If you’re looking for another big name in the HRM marketplace, then Wahoo's Tickr X makes a good bet if you’re predominantly cycling and/or running-focused. Nevertheless, it’ll also keep tabs on your heart if you’re down at the gym too.