Shimano dura ace r9100 double chainsetthe shimano dura ace r9100 double chainset has been completely re designed to offer the very best combination of light weight and stiffness it features shimanos iconic 4 arm hollow spider that is made from hollow forged aluminium although the crank arms and spider arms are noticeably bigger which increases stiffness the overall weight has dropped by 7g over the previous edition of dura ace shimano has adapted the crankset to work with disc brake road bi