The Shimano Ultegra R8150 Di2 12-speed Rear Derailleur shifting is easy and precise - just a light touch, as soft as a mouse click, is sufficient for the front or rear derailleur to instantaneously select the correct gear.

• the rear derailleur is now the brains of the system with wireless connectivity to the shifters. It acts as the point the system is charged, provides Ant+ connection to 3rd party devises and replaces the handlebar junction
• button on the derailleur for Di2 operations, and led light denotes synchronized shift mode, setting mode and charge requirements
• sleek appearance with low profile shadow design construction reduces risk of damage in a crash
• programmed automatic motion at the touch of a switch makes this derailleur quick, smooth and effortless to shift
• the removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching, but provides effortless gear shifts
• derailleur contains a saver (fuse) function, where the inner structure is protected from strong impacts
• high tolerance cold forged aluminium link plates and body construction is extremely light and durable
• four self-lubricating micro-machined fluorine-coated link pivot bushings provide low-friction shifting
• 12-speed e-tube Di2 compatible
• wide gear ratio compatible up to 11-34t