Suunto's chest strap has had a proper update. The Suunto Smart Heart Rate Belt 2 isn't simply a refresh of the original, it's a redesigned sensor with running form tracking, multi-device connectivity, and a smarter approach to cleaning up your heart rate signal.
If you're deciding whether it's worth the upgrade, here's what's actually changed.
A cleaner signal, beat for beat
The biggest change is under the hood. A new ECG front end identifies and rejects the artifacts that distort a heart rate reading the spikes and dropouts that show up during hard intervals or surges. A redesigned strap construction also shields the signal from static noise, so readings stay stable from the moment you clip in.
That high-resolution beat-to-beat R-R data is also what unlocks real-time ZoneSense on a compatible Suunto watch, giving you live feedback on your effort zone as it happens, not after the fact.
Running Form: A genuinely new feature
This is the headline upgrade. The Belt 2 adds a six-axis motion sensor that measures:
- Cadence
- Ground contact time
- Vertical oscillation
- Flight time
- Left/right ground contact balance
The original belt didn't offer any of this, it was heart rate and R-R data only. Paired with a compatible watch, the Belt 2 shows how your form holds up as speed rises and fatigue sets in, which is a meaningfully different training tool than heart rate alone.
Connect three devices at once
The original belt paired with one device via Bluetooth Smart. The Belt 2 holds three simultaneous Bluetooth connections — so a watch can record the session, a bike computer can show live heart rate, and your phone can run the app, all from a single pairing. For anyone doing a triathlon brick session or switching between devices mid-session, this removes a genuine friction point.
More memory, less reliance on range
The original stored R-R data so it wasn't lost when your watch was out of range. The Belt 2 extends this significantly, with around 20 hours of rolling R-R memory on the belt itself — read back by timestamp once you're reconnected, so the record is complete even after a long stretch apart from your watch.
Built to disappear
At 13 g and 36.5 × 36.5 × 8.5 mm, the Belt 2's transmitter is smaller and lower-profile than before. A soft strap and silicone grip keep it in place through surges and descents, and a single CR2032 cell gives around 460 hours of battery life, so it's rarely the thing you have to think about.
Suunto Smart Heart Rate Belt 2 vs the original: quick comparison
| Feature |
Original Smart HR Belt |
Smart Heart Rate Belt 2 |
| Heart rate & R-R data |
✅ |
✅ (redesigned ECG front end for cleaner signal) |
| ZoneSense support |
✅ |
✅ |
| Running Form (cadence, GCT, vertical oscillation, flight time, L/R balance) |
❌ |
✅ |
| Simultaneous Bluetooth connections |
1 |
3 |
| Onboard memory |
Basic R-R storage |
~20 hours rolling R-R memory |
| Transmitter weight |
— |
13 g |
| Battery life |
— |
~460 hours (1x CR2032) |
Compatibility
Core features (heart rate, R-R intervals, memory, ZoneSense) are supported on Suunto Vertical, Vertical 2, Race, Race 2, Race S, Run, Run 2, and Ocean.
Running Form is supported on Suunto Vertical 2, Race, Race 2, Race S, Run, and Run 2 — on some models it requires a custom sport mode, Suunto Plus, or post-workout analysis rather than live on-watch display.
Supported features vary by watch model, so it's worth checking your specific watch before buying if Running Form is the feature you're after.
In the box: Smart Module, Chest Strap, Quick Guide, Warranty.
The bottom line
If you already own the original belt purely for heart rate zones, the upgrade case is really about Running Form and multi-device pairing, if neither matters to your training, the original still does its job. But for anyone training by intensity, doing structured interval work, or wanting a genuine window into running form rather than just heart rate, the Belt 2 is a meaningful step up, not a cosmetic one.
Read next: Which Suunto Watch is Right for You?
Suunto Smart Heart Rate Belt 2: What's New, and Why It Matters
Suunto's chest strap has had a proper update. The Suunto Smart Heart Rate Belt 2 isn't simply a refresh of the original, it's a redesigned sensor with running form tracking, multi-device connectivity, and a smarter approach to cleaning up your heart rate signal.
If you're deciding whether it's worth the upgrade, here's what's actually changed.
A cleaner signal, beat for beat
The biggest change is under the hood. A new ECG front end identifies and rejects the artifacts that distort a heart rate reading the spikes and dropouts that show up during hard intervals or surges. A redesigned strap construction also shields the signal from static noise, so readings stay stable from the moment you clip in.
That high-resolution beat-to-beat R-R data is also what unlocks real-time ZoneSense on a compatible Suunto watch, giving you live feedback on your effort zone as it happens, not after the fact.
Running Form: A genuinely new feature
This is the headline upgrade. The Belt 2 adds a six-axis motion sensor that measures:
The original belt didn't offer any of this, it was heart rate and R-R data only. Paired with a compatible watch, the Belt 2 shows how your form holds up as speed rises and fatigue sets in, which is a meaningfully different training tool than heart rate alone.
Connect three devices at once
The original belt paired with one device via Bluetooth Smart. The Belt 2 holds three simultaneous Bluetooth connections — so a watch can record the session, a bike computer can show live heart rate, and your phone can run the app, all from a single pairing. For anyone doing a triathlon brick session or switching between devices mid-session, this removes a genuine friction point.
More memory, less reliance on range
The original stored R-R data so it wasn't lost when your watch was out of range. The Belt 2 extends this significantly, with around 20 hours of rolling R-R memory on the belt itself — read back by timestamp once you're reconnected, so the record is complete even after a long stretch apart from your watch.
Built to disappear
At 13 g and 36.5 × 36.5 × 8.5 mm, the Belt 2's transmitter is smaller and lower-profile than before. A soft strap and silicone grip keep it in place through surges and descents, and a single CR2032 cell gives around 460 hours of battery life, so it's rarely the thing you have to think about.
Suunto Smart Heart Rate Belt 2 vs the original: quick comparison
Compatibility
Core features (heart rate, R-R intervals, memory, ZoneSense) are supported on Suunto Vertical, Vertical 2, Race, Race 2, Race S, Run, Run 2, and Ocean.
Running Form is supported on Suunto Vertical 2, Race, Race 2, Race S, Run, and Run 2 — on some models it requires a custom sport mode, Suunto Plus, or post-workout analysis rather than live on-watch display.
Supported features vary by watch model, so it's worth checking your specific watch before buying if Running Form is the feature you're after.
In the box: Smart Module, Chest Strap, Quick Guide, Warranty.
The bottom line
If you already own the original belt purely for heart rate zones, the upgrade case is really about Running Form and multi-device pairing, if neither matters to your training, the original still does its job. But for anyone training by intensity, doing structured interval work, or wanting a genuine window into running form rather than just heart rate, the Belt 2 is a meaningful step up, not a cosmetic one.
Read next: Which Suunto Watch is Right for You?