Coros Heart Rate Monitor

The Coros Heart Rate Monitor is easy to use, connecting quickly and simply with accompanying apps. In contrast to many monitors, it is arm mounted and doesn't have many features, but it does the simple things well and it integrated into my workout routines easily. The accompanying Coros app is straightforward even when you aren't using a Coros watch, though it's not particularly useful.

On a practical level, too, the Coros has few flaws: it has a washable strap, it's splashproof, it has 38 hours of battery life and it charges quickly. It would be more convenient to use a different USB attachment, and it'd be useful to be able to track your heart rate through the Coros app, but those small gripes don't affect its overall usefulness.

> Buy now: Coros Heart Rate Monitor for £69 from Coros

Once you've paired the Heart Rate Monitor (HRM) to the Coros app via the QR code or Bluetooth – it took a while to detect the QR code so I used Bluetooth instead – the app will direct you to instructions on how to use it without a Coros watch. So straight away, the app is more or less redundant unless you have the Coros watch. Clearly, this HRM would have additional capacity when used with a Coros watch, but, as I discovered, this wasn't a major drawback.

The app tells you that you can use your "HRM without a Coros watch by setting up a connection with a third-party app". It then provides a list of compatible apps, with instructions for each. The compatible apps are Strava, Polar, Adidas and Nike.

However, I found it very easy to link the Coros to my bike computer – a Wahoo Elemnt Bolt – via the Wahoo app, which suggests that it works with any app rather than just the ones listed. If you are already pretty au fait with how your apps work then none of this should be a problem. It pairs with up to three apps at once, which is a handy option.

Opening up Strava, for example, and choosing the 'Record' option, your heart rate instantly displays at the bottom of the screen. You will need to have Strava Premium to analyse your heart rate data, but Wahoo will allow you to look at this without any additional subscription.

The data was pretty much what I expected. I had no reason to doubt the reliability of the reading at the end of my ride, though occasionally I would look down at my Wahoo mid-ride and see a sub-100 heart rate as I crested a 2km climb, which I found pretty hard to believe. This may have just been a lag in the Bluetooth communication between the Coros and the Wahoo, as the data overall looked well within the expected parameters.

> Buyer’s Guide: Best heart rate monitors

In order to compare the Coros' recording accuracy, I wore it at the same time as a Garmin Forerunner 745 smartwatch and compared the data. The graphs displayed the data differently (shown below, Coros top, Garmin bottom), but the increase, decrease, and plateau were identical on both of the monitors. As I'd hoped, the Coros was recording accurately.

The Garmin also uses LEDs to record heart rate. It's certainly a good sign that the Coros is recording the same data as a watch that costs over £200.

Lights action

There is a small light on the side of the Coros that flashes different colours to indicate "charging" and "in use".

Four very bright green LED lights beam into your arm to help detect heart rate, and these go off promptly once it's taken off your arm. This is what sets it apart from most chest monitors, which use sensor pads.

External light can mess with these sensors, so it's important to keep it totally flush with your skin. Coros says that the arm is a better place to record blood flow than the top of the wrist, and will produce similar accuracy levels to chest monitors.

Strap

The strap is constructed from soft elastic and does feel well made. I didn't find it annoying to wear underneath my layers as it didn't catch or snag on anything.

It can be adjusted to different widths, and I can't imagine a situation where it wouldn't fit someone. It isn't possible to adjust the strap while it's on your arm, it must be removed and then – with two hands – it's possible to slide the buckle up and down.

The sensor slides off so you can wash the strap easily.

Charging

It's charged via a USB Type-A cable which isn't one you come across very often. Being the scatterbrain I am, I have already misplaced the cable a few times and there definitely won't be a spare one of these lying around in the house. A more universal USB port would be preferable. The monitor port is magnetised so the cable is drawn towards it and clicks together satisfyingly.

Charging times were quick and within the expected parameters. The battery life matched up with Coros' claimed 38 hours of full usage, and while I wasn't able to test the 80 days of standby, it was still holding charge after sitting in a drawer for a week. You have to go into the Coros app to check the battery life.

Water resistance

It's water resistant to 3 atm, which means it's splashproof but can't be fully submerged. This was fine for my uses. It's less sweaty wearing it on the arm than on the chest, but it is more exposed to the rain.

Value

Compared with chest strap monitors, the Coros isn't a cheap option, and while it does have some useful attributes like attaching to the arm, essentially it is just a screenless heart rate monitor without any different modes or options. The optical light sensors make it feel more high-tech, but there doesn't seem to be total agreement on whether it is more accurate in real-life use than chest monitors. Plus you need to recharge this weekly, while chest HRMs mostly survive on a battery that'll go for a year or more.

The Wahoo Tickr, for example, costs £39.99 and Dave was very impressed with its simple but effective design.

But, catering for the arm gang, Wahoo's Tickr Fit Armband Heart Rate Monitor is just a fiver less than the Coros, and also uses optical heart rate technology to get an accurate reading.

In contrast to the Coros, the Polar Verity Sense Optical Heart Rate Sensor has a range of different modes. It uses something called PPG to record data, which differs slightly from the optical lights used by the Coros, though it won't make much difference to the average user. The Polar can be used without a phone or bike computer by setting the sensor to a basic record mode. It has 30 hours of battery life, which is shorter than the Coros.

John enjoyed using it but found the recharging unit a little odd. You can use it for swimming, too, but it's a slightly more expensive option at £86.50.

Stu tested the more upmarket Garmin HRM-Pro Plus, which will set you back even more – £119.99. He recommended it for those who are already tooled up with Garmin gear as it will work really well with the Connect app, storing data while you are out of range and then uploading it later on. The Garmin isn't rechargeable, instead using a CR2032 disposable battery which lasts for around a year. If you're after simplicity, though, he recommended Garmin's HRM-Dual at £59.99, which will do the basics well.

Conclusion

I'm a big fan of the Coros, which is a good purchase for anyone with pretty straightforward HRM needs who prefers an arm-mounted monitor. You'll need to recharge it every week, and it's pretty basic in terms of its performance capability, but that was fine for me. The design is great, and unlike some chest monitors there are no small parts you could potentially lose. That said, I challenge you to not lose the charger at some point.

Verdict

Straightforward arm-mounted heart rate monitor that does the basics well