Vivobarefoot Primus Flow Review: The Lightest Barefoot Race Shoe for Triathletes
At just 159g, the Vivobarefoot Primus Flow is the lightest shoe in the Vivobarefoot lineup and their first model with an ETPU midsole. For triathletes who want barefoot-style running with a touch of energy return, this is a genuine game-changer.
What Makes the Primus Flow Different
Vivobarefoot has traditionally avoided midsole cushioning entirely, but the Primus Flow breaks that rule with a 4mm ETPU (expanded thermoplastic polyurethane) midsole. This provides subtle energy return without drowning out ground feedback. Think of it as barefoot running with a thin layer of responsiveness — you still feel the road, but the shoe gives something back on push-off.
Key Features
- 159g weight — The lightest Vivobarefoot running shoe, comparable to racing flats from conventional brands
- 4mm ETPU midsole — Vivobarefoot’s first-ever midsole foam, providing subtle energy return
- Zero drop — Maintains natural foot position despite the added midsole
- Recycled upper — Lightweight, breathable construction that dries fast after rain or sweat
Race Day and Speed Work
This is the Vivobarefoot you want for race day. The 159g weight means minimal energy cost, and the ETPU midsole adds a snappy feel during tempo runs and intervals. For sprint and Olympic distance triathletes, the Primus Flow offers a genuine alternative to conventional racing shoes — you’ll sacrifice some cushioning over a half-iron distance, but for anything up to 10km off the bike, it’s superb.
The shoe also works brilliantly for speed sessions on the track or road. Strides, fartlek, and threshold runs all feel sharp and responsive. If you’ve built your foot strength with the Primus Lite, the Flow is the natural next step for faster running.
The Verdict
The Primus Flow is a significant step forward for Vivobarefoot. By adding a thin midsole without compromising ground feel, they’ve created a shoe that bridges the gap between pure barefoot and performance racing. At £150 it’s a premium choice, but for experienced barefoot runners looking for a race-day edge, it delivers.
Price: £150 | Use code VIVO15MAR for 15% off full price items this March.
Shop Primus Flow on Vivobarefoot
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