Saucony Endorphin Speed 5 vs Mizuno Wave Rebellion Flash 3:
Which to Choose

Start with how close they are: the Endorphin Speed 5 weighs 241g and the Wave Rebellion Flash 3 weighs 244g (men's US 9), a difference you will never feel on foot, and both sit in the same 4:00–4:45 min/km optimal-pace band. The clearest hardware split is stack and geometry. The Mizuno is the taller, more aggressive shoe — a 40mm heel / 33mm forefoot platform driven by an Enerzy XP (TPEE) top layer over an Enerzy NXT (EVA) base and a glass-fiber-reinforced nylon Wave plate — with a pronounced rocker and exaggerated heel bevel that almost tip you into the next stride once you're at tempo. The Saucony sits lower at 37mm heel / 27mm forefoot on beaded PWRRUN PB (PEBA) with a semi-rigid winged nylon plate that guides transitions rather than snapping them. Drops are close (8mm stated, nearer 10mm measured, on the Speed 5 versus a measured ~7mm on the Flash 3), so both keep a moderate, forward-leaning slope. Where they genuinely diverge is versatility and ride character. The Endorphin Speed 5's softer, livelier PEBA and more forgiving plate make it comfortable for a wider range of paces and foot strikes — it's rated for 10K, half, and marathon, and can handle long marathon-training miles. The Rebellion Flash 3 is more specialized: its firmer forefoot, tall platform, and dramatic rocker reward a committed midfoot or forefoot landing and an honest, purposeful effort, but that same geometry feels tippy and unsettled at a jog, and it tops out at 10K and half — it's not built for slow long runs. In short, the Saucony is the smoother, do-more shoe; the Mizuno is the sharper, more insistent one that wants you to run fast.