Is the On Cloudboom Echo 3 a race-only shoe or can it handle training runs?

The Echo 3 is built as a race-day shoe: the carbon Speedboard and Helion HF superfoam are tuned for race pace, not easy recovery miles. Using it for training will compress the foam faster and shorten its useful life. On recommends keeping it for race day and tempo sessions only, and rotating a daily trainer alongside it.

What is the Undyed White Mint colourway and how is it made differently?

The Undyed build uses a natural, undyed yarn for the upper rather than synthetic dyeing processes, reducing water and chemical use in production. The Mint detailing comes from minimal tonal accent rather than a full dye run. The performance specs are identical to the White Flame; the difference is purely in the materials process and the quieter colour.

How does the Cloudboom Echo 3 fit compared to On's everyday trainers?

The Echo 3 fits about half a size shorter than On's everyday Cloud models due to the sock-like knit upper pulling closer to the foot. Most runners go true to size but check the per-product guide. The upper locks down well for racing; if you wear thick race socks, go true to size and the snug fit will still work.