The Shimano ULTEGRA RD-R8150 12-speed rear derailleur not only provides the fastest and most precise shifting performance on the market, but is also more flexible than ever before. The rear derailleur is now compatible with 11-34T and also 11-30T cassettes. The compact rear derailleur contains the wireless unit, the charger and the mode button - and has a lot going for it! THE SCIENCE OF SPEED: Shimano ULTEGRA Di2 12-speed Rear Derailleur RD-R8150. Great speed means great responsibility. That's why, faced with the task of making ULTEGRA groupset even faster, Shimano decided to take a holistic and 100% performance-focused approach. Shimano's 12-speed road groupset delivers unparalleled control and comfort anytime, anywhere - whether you're competing in an amateur race, chasing your personal best, or out for a social ride. That is "Science of Speed". And it's what sets SHIMANO apart from the rest.

TECHNOLOGIES

SHADOW RD - the mechanism rear derailleur, SHIMANO SHADOW RD, is intended for more aggressive riding. Its super low profile design carries many benefits. Because of its low profile and single tension construction, the derailleur does not hit the chain stay in rough riding conditions. The result is smooth and silent performance.

SEIS SHIMANO ELECTRONIC INTELLIGENT SYSTEM - The SEIS innovative shift technology is still based on the SHIMANO INDEX SYSTEM (SIS) that has proved its superior gear changing characteristics over the years. The big difference is that in this case, the shifting action is provided for by electronics instead of mechanics. This electronic shifting system has been extensively tested over past two years by several professional riders in all conditions possible, such as rain, mud, low temperatures, cobble stone roads and combinations of all of these at the same time. Shifting is executed by simply pressing the button. No power is needed to shift, which gives important advantages since it is easier now to always keep a tight grip on the handlebar and to keep your concentration on riding instead on shifting. The shift system allows accurate and effortless shifting in difficult circumstances like when you have cold hands or when you are completely exhausted. Furthermore, the shifting performance will never be affected by contaminated or stretched cables since the shifting signal is transferred electronically. The operating buttons work similarly to mechanical Dual Control Levers so you dont need to re-program your mind for a system.

E-TUBE - platform offers optimum flexibility on your bike. E-TUBE transmits interactive signals and power supply to each parts by "Plug and play connection. E-TUBE is no rust, no stretch, no freeze and it ensures advanced low maintenance. And SM-PCE1 connects between PC and components to update firmware. Digital device stay the latest version with updating firmware for improve function.