FLOWBIO Sweat Sensor
Measures your real-time fluid and sodium loss during exercise. Paired with the FLOWBIO app, Advanced Hydration Intelligence (AHi®) turns your sweat into an end-to-end hydration system — so you know what to drink, when, and why.
- Real-time sweat loss (L/hr) & sodium loss (mg/L)
- Built-in skin-temperature sensor
- 100-hour battery · USB-C charging
- FLOWBIO arm strap included — or wear on your HR chest strap
- Works with Garmin, Wahoo, COROS & Zwift
- iOS & Android · predictive hydration planner
The one number that changes every session.
The FLOWBIO Sensor measures fluid and sodium loss continuously throughout exercise — together, the data point that varies most between athletes and between sessions. Sweat rate and sodium concentration shift with temperature, intensity, heat acclimation and your own physiology, so every ride produces a unique loss profile. The sensor captures that profile as it unfolds, instead of estimating it from population averages.
Everything in the box, and on the chip.
Sweat data, in the same view as power.
Real-time on your head unit
Streams live fluid and sodium loss to the Wahoo ELEMNT ACE, BOLT 3 and ROAM as a native data field — right beside power, pace and heart rate — so you adjust intake during the ride, not after. Garmin, COROS and Suunto support is rolling out in beta.
Who it's for
Athletes who already train with structured data — cyclists, triathletes and runners working from power, pace and heart rate. And the coaches, sports scientists and performance staff who run applied programmes, including teams at WorldTour, T100 and professional triathlon level.
Where you wear it
Designed to sit on an existing heart-rate monitor. It supports both optical arm-based monitors and chest straps, so you can wear it on the upper arm or on your back — whichever your setup prefers. The FLOWBIO arm strap is included.
No needle. No patches.
The sensor collects sweat through a tiny channel driven by your own sweat glands — reusable, session after session, with no needle and no patch to post off to a lab. First stable sodium reading arrives about eight minutes into a ride.
Validated against the lab gold standards.
The sensor's accuracy was established in an independent, peer-reviewed validation study (Frontiers in Physiology, 2025), measured directly against laboratory reference methods — the same standards used in sport-science research. 90% accurate in lab conditions; in the field, sodium within ~180 mg and fluid within ~250 mL of the gold standards.
Buying & using it in South Africa.
How much is delivery and how long does it take?
Delivery is free across South Africa, fulfilled by MTBApp. When stock is available in South Africa, delivery typically takes around 3 working days. Back-ordered items ship with our October import from the UK. Either way, you'll receive an email with tracking once your order is confirmed.
Do I need my phone with me to use it?
You can train without your phone nearby, but you'll need your mobile device to sync the sensor and view your data in the FLOWBIO app. The app currently supports cycling, running and walking.
Where do I wear the sensor?
On an existing heart-rate monitor — optical arm strap or chest strap — so either the upper arm or your back. A FLOWBIO arm strap is included in the box.
How does payment work?
Checkout is handled securely by PayFast — card or Instant EFT. Your card details are entered on PayFast's secure page, never stored by us.
How accurate is it, really?
It's been independently validated in a peer-reviewed study against laboratory gold-standard methods. See the full study and numbers on our Science page.