Shimano Dura-Ace Di2 Electronic Rear Derailleur

Ride into the 21st century with Shimano's heralded Dura-Ace Di2 Electronic Rear Derailleur. Instead of a cable and spring, it's driven by a servo motor so shifts are identical, fast and precise every time. It runs off the Di2 rechargeable L ...(Read More)

Shimano Dura-Ace Di2 Electronic Rear Derailleur
$739.95
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Ride into the 21st century with Shimano's heralded Dura-Ace Di2 Electronic Rear Derailleur. Instead of a cable and spring, it's driven by a servo motor so shifts are identical, fast and precise every time. It runs off the Di2 rechargeable Li-ion battery pack (sold separately), which attaches to the bottle cage bolts, holds a charge that lasts for approximately 1,500 miles, and is completely sealed from the elements. Plus, the derailleur is designed to move inward under impact to reduce the potential for damage in a crash. The derailleur also boasts a light, tough carbon pulley cage and the chain-wrap capacity for standard and compact cranksets. And, there aren't any cables or housing to stretch or fail, so you get peace of mind.

An important part of a rear derailleur's job is keeping the chain taut as you change gears. Chain-wrap capacity is a number that tells whether or not a derailleur will be able to do this on the drivetrain you plan to use it on. Calculate chain-wrap capacity with this formula: Chain-wrap capacity = (large chainring - small chainring) + (large rear cog - small rear cog). Example: 53/42 chainrings and a 12-23 cassette: (53 - 42 = 11) + (23 - 12 = 11) = 22-tooth chain-wrap capacity.

Part Numbers

UPC MPN
00689228278622 IRD7970SS