Stop guessing.
Start measuring your sweat.
Hydration is the most individual variable in endurance sport — and the one almost every athlete guesses. FLOWBIO measures your real fluid and sodium loss, so you know exactly what to drink and when.
Dehydration is quietly costing you performance.
You can't feel a 2% fluid loss — but your body does. The research on what dehydration and sodium loss do to an athlete is not subtle.
Figures drawn from published sports-science research on hydration and sweat sodium loss.
"Drink to thirst" was never a strategy.
Generic advice — a bottle an hour, a scoop of electrolytes — ignores the two things that actually decide your race: how much you sweat, and how salty your sweat is. Both are wildly personal, and both change with heat, altitude and intensity. Guess wrong and you pay for it:
- Cramps and heavy legs late in the race
- Bonking and foggy focus when it matters most
- GI distress from over- or under-drinking
- Slower recovery between hard days
Four reasons to know your numbers.
Protect your performance
Stay ahead of the 2% line where power drops, heart rate climbs and focus fades. Replace what you actually lose — no more, no less.
End the cramps & bonk
Cramping and mid-race fade are often a sodium and fluid problem. See your real losses and fix the actual cause instead of guessing.
Fuel to your body
Your sweat rate and sodium concentration are as unique as a fingerprint. FLOWBIO turns them into a plan built for you, not the average.
Own race day & heat
Losses spike in heat and at altitude. Walk to the start line knowing your plan holds up when conditions turn against you.
Data in. Strategy out.
Wear it
Clip the sensor on and train. No needle, no lab — it reads your sweat in real time, as you sweat.
See your loss
Live fluid & sodium loss on your Garmin, Wahoo or COROS head unit — or in the app.
Act on it
STACK'D turns your numbers into the exact sachets to drink, and precisely when to take them.
STACK’D — an MTBApp product · launching soonNumbers you can actually trust.
The FLOWBIO Sensor has been independently and peer-reviewed against laboratory reference methods for sweat fluid and sodium measurement. This isn't a wellness gimmick — it's hydration data measured, compared and published under scientific scrutiny, so the plan you build on it holds up.
reviewedPublished validation
gradeReference-method accuracy
timeLive, on-body readings
From WorldTour pros to weekend warriors.
The riders who live and die on their numbers already refuse to guess. Now you don't have to either.
Buy the FLOWBIO Sweat Sensor.
View the full product page & specs →
FLOWBIO Sweat Sensor
The world's most accurate wearable sweat sensor — real fluid and sodium data, straight to your device. Shipped free across South Africa.
Questions, answered.
Do I really need to measure my sweat?
If you train or race for more than about an hour — especially in the heat — yes. Sweat rate and sweat sodium vary enormously between people, so generic "drink a bottle an hour" advice is a guess. Measuring yours once changes how you fuel every session after.
Which devices does it work with?
The sensor pairs with Garmin, Wahoo and COROS head units, and with Zwift, so your live fluid and sodium loss shows up right alongside your power and heart rate.
How does it connect to STACK'D?
STACK'D takes your measured losses and turns them into the exact electrolyte sachets to drink and when — a plan built on your real numbers instead of the average athlete's. STACK'D is an MTBApp product, launching soon.
How long does delivery 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 get an email with tracking once your order is confirmed.