Shimano Dura Ace FC-9000 11 Speed Outer ChainringShimano Dura Ace FC R9100 11 Speed Outer Chainring With their special tooth profiles, recording pens and climbing aids allow the Dura Ace 9000 chain leaves a particularly soft and fast switching operation. So is with them a load switching, how it was normally only used by the derailleur, without any problems. Its construction made of carbon fiber reinforced plastic with aluminum teeth helps to keep the weight low, while increasing the torsional