Fit
The length for the Onyx is true to size, and the toe box runs a bit narrow. The last feels snug in the rearfoot and looser in the midfoot. A thin padded tongue and traditional lace system help stabilize the midfoot fit, but our testers still found it sloppy with high-agility running. 

Comfort
The heel cup is large and rather stiff, causing some mild irritation in the Achilles area for some of our users. The seamless mesh upper has no sewn overlays, and felt comfortable against the foot without any rubbing or hot spots. Ventilation of the mesh upper is quite effective for temperature regulation in warm weather.   

Responsiveness
Three layers of material combine for cushioning and energy return on the Onyx: the lowest level is a stable rebound EVA that blends with the outsole rubber for high-density rebound. Above that is a layer of 361’s Quickfoam midsole material, and the molded insole above that also has a thin layer of softer foam to further enhance impact resistance. We found the Onyx to have a very firm feel, but with minimal bounce or energy return after impact. 

Ride Quality
The Quickfoam midsole has comfortable cushioning, but is lacking an appreciable transfer of momentum from rearfoot to forefoot. A full-contact blown rubber outsole ensures solid ground feel at cruising speed, and the segmented outsole provides a bit of forefoot flexibility, although the shoe feels quite stiff overall. With a 9mm heel-toe drop, the Onyx is much better suited for heel strikers than midfoot strikers. 

Speed
This is the heaviest shoe in our test group, and when combined with a stiff feel and limited responsiveness, the Onyx makes you work to earn your speed.