Shimano Road Rear Derailleurs

The lightest Shimano rear derailleur at 207.5 grams. It is SIS compatible using the Double Servo-Panta Mechanism and can be used in a 6, 7, or 8 speed shifting system. This changer is made of aluminum where ever possible. Only the mounting and pivot bolts holding it together and the pivot points are made of steel. Shimano has made efforts to seal all the points of dirt contamination including; sealed link pivots (the four stainless steel pins that the body revolves on) using tiny flanges, sealed pulleys achieved by using interlocking seals surrounded by a rubber o-ring, and a sealed axle bracket (the threaded bolt and housing that fasten the derailleur to the frame dropout) using an o-ring seal. The guide pulley has an aluminum outer wheel that the chain runs around increasing it's life over the standard plastic pulleys. The pulleys use interlocking seals to seal them against contaminates, and where the bolt holding the pulley in the cage passes through the pulley, there is a small ceramic bushing that revolves inside a larger ceramic bushing sleeve to reduce friction. This ceramic bushing arrangement is Shimano's alternative to using precision sealed bearing cartridges to reduce friction, but lets remember that engineers continue to talk about making car engines out of ceramics because they are lightweight and have reduced friction over steel to steel construction. The cage is constructed with a chain retainer to prevent the chain from being removed accidentally and the front facing edges of the cage have been rolled to prevent them from catching spokes in the event of an overshift. Included in the adjustments you can make are; the return spring force, high and low gear, B-Tension adjustment and there is a convenience adjuster to take up cable slack. The steel mounting, pivot and pulley bolts can be replaced with SRP Titanium versions and are writen about at the end of this article. A 5mm hex wrench installs and cinches the cable. The Dura-Ace rear changer will accept a maximum rear cog of 26 teeth and a minimum rear cog of 12 teeth. The greatest difference in size between the two front chainwheels can't exceed 14 teeth and the Total Capacity for this derailleur is 26 teeth. $ Price in Catalog

The Ultegra rear derailleur uses the Double Servo-Panta Mechanism and is SIS compatible for use in 6, 7 or 8 speed systems. The major body parts and the cage are made of aluminum, while the adjusting and fastening bolts are made of steel. This changer weighs only slightly more than the Dura-Ace one at 225.5 grams, and has many of the same features. The link pivot points are sealed with flanges like the DA rear, the bracket axle (mounting bolt) is sealed the same way, and uses the same seal system for the pulleys that the DA does. The guide pulley does not have the aluminum outer wheel like the DA rear does, though it does have the ceramic bushing arrangement. The tension pulley doesn't have the ceramics of the guide pulley, instead it has a steel sleeve and steel bushing set into the plastic pulley. The cage is styled to prevent an overshift from jamming the cage into the spokes of your rear wheel. There are adjustments for high and low gear, B-Tension adjustment, and a convenience adjuster for cable slack. The steel mounting, pivot and pulley bolts can be replaced with SRP Titanium versions and are writen about at the end of this article. Installation is performed with a 5mm hex wrench. The maximum rear sprocket for this derailleur is 28 teeth, while the minimum is 13 teeth. The greatest difference in size between the two front chainwheels can't exceed 13 teeth and the Total Capacity for this derailleur is 28 teeth. $ Price in Catalog

Shimano is now making high-end road bikes affordable with the introduction of the 105 SC group. The heart of the group is the 105 SC rear derailleur. Like it's big brothers, the 105 SC has a double Servo-Panta mechanism which has swift response and flawless execution. The 105 SC has sealed link pivots and a sealed mounting bolt axle to reduce maintenance and friction. It is SIS compatible with a 6, 7 or 8 speed system, and has the spoke protection of the Ultegra and the Dura-Ace model. The steel mounting, pivot and pulley bolts can be replaced with SRP Titanium versions and are writen about at the end of this article. Made in a short cage version only it will accept a maximum rear cog of 28 teeth, (28 tooth capacity), and reach down for a 12 tooth high gear. The 105 SC rear is made of aluminum and steel, it weighs 246 grams. $ Price in Catalog

The low cost, high quality replacement changer for your bike. It has, however a number of features that the more expensive ones have. Like the Dura-Ace rear, there are adjustments for return spring tension, B-Tension adjustment, high and low gear adjustments, and a convenience adjuster for cable slack. Installation and cable fastening are done like the DA rear, with a 5mm allen wrench. The body is made of aluminum and steel, while the pulley cage and bolts are made of steel. The pulley cages are made of plastic with a polished steel bushing to revolve on, while thin steel caps keep dirt out of the whole mechanism. The cage is fashioned to prevent spoke damage in an overshift. The RX100 weighs 279 grams. The maximum rear sprocket for this derailleur is 28 teeth, while the minimum is 12 teeth. The greatest difference in size between the two front chainwheels can't exceed 13 teeth and the Total Capacity for this derailleur is 28 teeth. Right between the DA and the Ultegra. $ Price in Catalog