New Balance Fresh Foam X 860v15 vs On Cloudmonster 3:
Which to Choose

Start with ride feel, because that is where these two genuinely part ways. The 860v15 uses soft, single-density Fresh Foam X that feels plush and pillowy — it absorbs far more than it returns, giving a calm, protective ride that can go slightly floaty when you slow right down. The Cloudmonster 3 takes the opposite approach: its Helion foam is firm and planted, sitting you on a big, composed platform with mechanical, predictable transitions and little give at a crawl. Neither is bouncy — both plates (New Balance's medially-wedged plastic Stability Plane, On's TPU Speedboard) add structure, not pop — so if you want energy return for tempo work, neither is the answer; but soft-and-cushioned versus firm-and-stable is a real fork, and it should drive the choice. Support is the other divider: the 860v15 is a true stability shoe, with that full-length medial Stability Plane gently correcting mild-to-moderate overpronation, whereas the Cloudmonster 3 is stable-neutral — it gets its steadiness from a wide, planted base with no medial post, which suits neutral to only mildly pronating feet. The numbers are close enough to be nearly a wash: stack is 40mm/32mm on the 860v15 versus 39mm/32mm on the Cloudmonster 3, and drop is 8mm versus 7mm. Weight is the clearest spec gap — the 860v15 comes in at about 332g in a men's US 9 against 301g for the Cloudmonster 3, so the On is the lighter, less lumbering of the two, while the New Balance's denser midfoot-and-heel upper also runs warmer on hot days. Both peak on relaxed long and steady efforts and fade when you push the pace, with their sweet spots landing within a hair of each other.