Adidas Adizero Boston 13 vs Saucony Endorphin Speed 5:
Which to Choose

On the numbers they are close but not identical. The Endorphin Speed 5 is the lighter of the two at 241g against roughly 254g for the Boston 13, and it runs a taller, higher 8mm drop (near 10mm in practice) versus the Boston's lower 6mm offset — you sit a touch higher in the heel on the Saucony (about 37mm) than on the Adidas (about 34mm), while the Boston keeps slightly more foam under the forefoot, which suits runners who like to feel connected to the ground up front. The bigger split is structural. The Boston pairs a soft PEBA-class Lightstrike Pro top layer over a firmer Lightstrike 2.0 carrier and threads glass-fiber EnergyRods through it, so the ride is dual-density, planted, and quick to roll — the rods snap you forward and reward a faster cadence, and the firmer base plus a broad platform give it the edge in stability (4/6 vs 3/6). The Speed 5 goes all-in on full-length beaded PWRRUN PB (PEBA) with a semi-rigid winged nylon plate that guides rather than snaps; the result is softer, bouncier, and more flexible, smoother and more forgiving at toe-off but a little less locked-down than the Boston's firmer chassis. In feel, the Boston can read as stiff and busy at true easy-jog pace and comes alive when you push into its 3:50-4:30/km zone, with the half-to-marathon as its sweet spot; the Speed 5 also prefers a rhythm (its optimal band sits slightly slower at 4:00-4:45/km) and shines best at the half. Both wear breathable engineered mesh uppers, both use composite rather than carbon plates, and neither is a plush recovery cruiser.