Equipped with an oversized, 22mm diameter Cr Mo bottom bracket spindle, the ES25 features an innovative Octalink splined axle/crank arm interface, allowing for stiffer, more rigid crank assembly than seen on most common square-tapered spindles. It also benefits from a rubber sealed cartridge assembly with larger ball bearings, making for a low maintenance BB that works hard to keep muck & mud from impacting its performance.