New Balance FuelCell Rebel v4 vs New Balance FuelCell Rebel v5:
Which to Choose

The clearest change is under the foot. The v4 sits at roughly 28 mm heel / 21.5 mm forefoot, while the v5 grows to about 33 mm / 27 mm — around 5 mm more stack at both ends — and swaps the v4's nitrogen-infused pure-PEBA midsole for a PEBA+EVA FuelCell blend that actually rides softer, not firmer, than the taller number would suggest. New Balance also added a rocker profile to the v5 that the v4 doesn't have, so the newer shoe rolls you forward through the gait cycle rather than relying purely on foam rebound and quick turnover. Both keep the 6 mm drop, the plateless neutral platform, and a breathable engineered-mesh upper, and both stay light — the v4 lands around 213 g and the v5 only marginally heavier at roughly 220 g in men's US 9.5, so neither feels like it gained real bulk. The practical result is a shift in personality: the v4 is firmer, lower, and more planted, snappiest when you're genuinely flying (its optimal window sits around 4:00–4:45 min/km), which is why it grades a notch faster on pace. The softer, taller v5 wakes up a touch later, around threshold effort, is more forgiving on longer efforts and faster easy days (an uptempo-trainer zone closer to 4:15–5:15 min/km), but trades away a little of the v4's snappy, connected-to-the-ground feel and can read as slightly less planted at very slow jogging paces. Durability nudges in the v5's favor conceptually too, though both use a thin outsole — the v4's exposed-foam sole is a known high-mileage weak point, and the v5's coverage is similarly minimal.