Shimano is one of the premier designers of bike gear-shifting systems, and they manufacture full lines of both front and rear derailleurs. Shimano's derailleurs are designed for either road bikes or mountain bikes, with several different types of derailleurs available for each of the major types of bicycle. In 2010, most Shimano derailleurs are part of the Dura-Ace product line.
Dura-Ace 7900 Rear Derailleur
The Shimano Dura-Ace 7900 rear derailleur is made from carbon pulley plates, making them lightweight yet also rigid. It also features cold forged aluminium and plastic. It is designed for use with road bikes.
Dura-Ace 7900 Front Derailleur
The Shimano Dura-Ace 7900 front derailleur is made from forged aluminium, with the chain guide made from nickel-plated aluminium. Features of this derailleur include a trimless front chainring, and a wide link design that allows for greater stiffness. These derailleurs weigh about 67g, and are intended for use with road bikes.
Dura-Ace Di2 7970 Rear Derailleur
The Shimano Dura-Ace Di2 7970 rear derailleur is an electronic rear derailleur, allowing for the most accurate and rapid shifting possible with a road bike. Like the non-electronic models, the pulley plates are made from carbon, while the metal elements are made from aluminium. These derailleurs fit with a 10-ring cassette.
Dura-Ace Di2 7970 Front Derailleur
The Shimano Dura-Ace Di2 7970 front derailleur is essentially the "brain" of Shimano's Di2 electronic shifting system. It contains the shifting logic that keeps the shifters in constant contact with the rest of the shifting system. According to Shimano's website in 2010, this derailleur allows for the most perfect front shifting available on the market today.
XTR M980 Front Derailleur
Shimano's most popular line of off-road drive systems is the XTR line, part of which is a line of both front and rear derailleurs. The Shimano XTR M980 front derailleur is made to fit with a 10-speed cassette. It has a universally interchangeable clamp band mounting, dual spike technology and an aluminium outer plate.
XTR M980 Rear Derailleur
The Shimano XTR M980 rear derailleur has a re-engineered architecture from previous models to allow for greater stability. The rear derailleur has a carbon outer plate and is designed to be a part of a 10-speed gear shifting system.