Fit

To our testers the Cloudflow fit is long and narrow; they don’t accommodate wide feet, and if you’re a “tweener” on sizes, opt down a half size for the best length. We also had some issues with stability of the uppers, particularly the tongue and laces; the tongue is very thin and has a tendency to fold or bunch up when the laces are cinched tight, and the laces themselves are a bit thin and slick to maintain their tension.  

Comfort
The woven mesh material of the upper is a highlight of the Cloudflow: it has outstanding breathability and durability, and it adapts to contours of the foot in a similar manner as Nike’s Flyknit material.  The interior has a built-in sockliner that is plush and prevents any chafing or hotspots. 

Responsiveness
The Cloudflow uses 18 “clouds” to independently cushion impact and propel forward momentum.  The cloud lugs also extend further up the toe than on other On models, with a large channel between the lateral and medial rows of lugs. Complementing the cloud lugs is a lightweight Zero-Gravity EVA foam, which is softer and more resilient in the Cloudflow than with previous On models. Our testers were very impressed with the energy return from impact and push off from the road. The 6mm heel-toe drop allows the cloud mechanism to be equally effective for heel strikers and midfoot strikers. 

Ride Quality
On utilizes a redesigned Speedboard in the rearfoot to facilitate transfer of energy from heel to toe, and functions as a rocker to promote a natural rolling from heel to toe. The independent cloud pods and soft EVA create a highly flexible midsole that accommodates foot movement very well, and a new outsole rubber compound provides nice grip on the ground. Our testers love the cushioned ride of the midfoot and forefoot, even with higher demand situations like track work or hard cornering on the road. The lower profile lugs in the forefoot have less room to compress and definitely have a firmer feel than the rearfoot to help with propulsion forward. 

Speed
Weighing in at a mere 7.8 oz and providing great responsiveness, the Cloudflow shoe is virtually pure quickness.  Leg turnover is no problem, and agility isn’t compromised as much as we feared with the unorthodox pod configuration. Long-duration comfort may be an issue, so the Cloudflow seems best suited for speed training days or short distance (up to half-marathon) road racing.