Our modern world of bottom brackets is something of a labyrinth; if you can decipher the clues to find your way to the one that works for you, we commend you. But if a few shadowy paths still leave you uncertain or confused, let us try to illuminate one of them for you. The Dura-Ace BB-R9100 Bottom Bracket has stood as a bellwether for solid, reliable bottom bracket design since Shimano wisely embraced external bottom bracket technology when it wasn't yet popular. Despite new bottom bracket standards bombarding us more often than ever, Shimano keeps its faith in this serviceable, reliable, and exceptionally durable design, and for good reason. Improved seals ensure a quieter ride and reduce drag, and the smaller friction-reducing bearings that first appeared on Dura-Ace 9000 return to smooth your ride once again.