FLOWBIO has today announced the launch of S1, the most accurate wearable hydration sensor for triathletes, cyclists and runners.

Designed and developed in London, the S1 measures water and sodium losses in real-time. Using an advanced algorithm, it builds a personalised, actionable hydration profile, presenting recovery, preparation and in-session hydration plans for optimal performance.

FLOWBIO device

Worn against the skin, clipped onto either a chest or optical heart rate strap, the S1 and S1 Companion App provide athletes with accurate hydration insights out in the real world. This allows for usage in the same conditions and environments that athletes will be training and competing in.

Each S1 is carefully hand-assembled and individually tested at FLOWBIO’s London HQ, to ensure the highest levels of accuracy and quality.

Backed by the founder of the category-defining Oura Ring and used by elite athletes such as the EF Pro Cycling team and Olympic champion triathletes the Brownlees, the S1 is already revolutionising how top competitors comprehend their own hydration.

Stefan van der Fluit, CEO and Co-Founder of FLOWBIO, ‘Wearable technology for endurance sports athletes has come a long way and yet, until now, anyone without regular access to a lab and a knowledgeable sport scientist has had to rely on estimations based on body weight. Sweat rates between athletes of a similar weight can vary significantly and that’s before you consider additional factors such as activity intensity, air temperature and humidity.Following significant research, development and sweat, we’re incredibly proud to present the S1 as the solution for athletes serious about their performance, providing accurate, athlete-specific hydration insight’.


Sophie Killer, Performance Nutritionist for Olympic & Professional Athletes, ‘For athletes who have busy lives, multiple commitments and, for much of the year, demanding training and racing schedules, it’s simply not feasible for them to carve out multiple days each season for lab testing under a variety of conditions. Having access to technology which enables frequent hydration analysis across a range of different environments with no interruption to their training allows unprecedented, personalised insight into an, as-yet, relatively untapped performance gain. We’re really excited to explore how the S1 can further our, and our athletes’, understanding of hydration for performance and recovery.’

The S1 is available to order from www.flowbio.com, priced at £329.

FLOWBIO Companion App