Garmin HRM-Dual Review

Most heart rate straps are sold on features you will never use. Running dynamics, swimming modes, recovery scores, proprietary app ecosystems. The Garmin HRM-Dual is the opposite proposition: an ECG chest strap that broadcasts your heart rate over ANT+ and Bluetooth at the same time, costs about half what the premium straps cost, and runs for up to three and a half years on a coin cell.

For an indoor cyclist, that is very close to a complete answer — and the questions worth asking are what you give up at this price, and whether the two things you give up matter.

The battery figure is not a typo

Garmin quotes up to 3.5 years from a CR2032 at an average of one hour of use per day. That is the best battery specification in the category by a very wide margin — the Polar H10 manages up to 400 hours, and rechargeable straps like the Wahoo TRACKR run around 100 hours per charge.

This matters more than it sounds, because a heart rate strap is a device you want to stop thinking about. Every rechargeable sensor in a pain cave is one more thing that can be flat when you have forty-five minutes and the motivation to use them. With a multi-year cell, the strap is simply always ready, and when it eventually is not, the fix is a CR2032 from any supermarket and a coin to open the door.

Unlimited ANT+ connections: the indoor advantage

Garmin publishes an unusual detail — unlimited simultaneous ANT+ connections, and two Bluetooth connections. That asymmetry is worth understanding, because it maps directly onto how an indoor setup actually works.

ANT+ is a broadcast protocol: the strap shouts its heart rate into the room and any number of devices can listen without the strap knowing or caring. Bluetooth is a paired protocol: a connection is negotiated, and the number of simultaneous partners is limited.

In practice, a typical pain cave has a tablet running Zwift, possibly a head unit recording a backup file, and a trainer that may itself want to relay the strap. On a single-connection sensor, the first device to claim the signal keeps it and the others show nothing — one of the most common frustrations our connection troubleshooting guide deals with. If your devices speak ANT+, the HRM-Dual sidesteps that entirely. If you are Bluetooth-only, an ANT+ adapter is a cheap way to unlock the better half of this strap.

What you actually give up

Two things, and for most riders neither is decisive.

No onboard memory. The H10 can record a session by itself and sync afterwards. The HRM-Dual cannot; it needs a receiving device present. Indoors that is rarely an issue, since the whole point of the session is that something is displaying it — but it does mean that if Zwift crashes at minute fifty, the heart rate data goes with it.

No premium strap.Polar's Pro strap uses silicone dots that grip properly; Garmin's plain elastic is more prone to creeping down your ribs during hard efforts, which shows up as dropouts and spikes. This is fixable — fit it snugly and wet the electrodes — and it is the single most common cause of bad readings on any strap.

What you do not give up is accuracy. The HRM-Dual measures the same electrical signal with the same technology as straps costing twice as much, and it reports heart rate variability as well as heart rate. The premium in this category buys HRV fidelity, recording and comfort — not a fundamentally better heart rate number.

Living with it indoors

Wet the electrodes before every ride. This is the whole maintenance routine and skipping it is responsible for most of the "my heart rate says 195 in the first two minutes" reports on every forum. The strap needs a conductive path to your skin and does not have one until you sweat.

Rinse it afterwards. Indoor sweat is far more concentrated on kit than outdoor riding, because it lands in one place for an hour with no airflow unless you have a proper fan — which, incidentally, is the single accessory that improves an indoor session more than anything else. Salt degrades both the elastic and the conductive fabric, and a strap that has gone hard or stopped gripping should be replaced rather than argued with. The sensor pod will outlast several straps.

Pair it as a heart rate source in your app of choice; if your trainer supports a heart-rate relay — the Kickr Core 2 does — routing the strap through the trainer removes one more connection from the chain.

Do you need a heart rate strap at all?

Honest answer: if you own a smart trainer or a power meter, power is the better primary number for prescribing and executing training. It responds instantly, it does not drift with heat or caffeine, and it is what structured workouts are written in.

Heart rate remains useful as the second number — it tells you what a given wattage is costing you today, which is exactly the information power cannot provide. That comparison is the subject of our power meter vs heart rate guide, and the practical conclusion is that a cheap accurate strap alongside power beats an expensive strap on its own.

Which is precisely the case for this one.