Shimano Mountain Bicycle ATB Rear Derailleurs

The XTR rear is a part of Shimano's eXTRa expensive group of components. The XTR rear derailleur in a way has more in common with the Dura-Ace rear than the XT rear. The XTR has the same even dull cast that the Dura-Ace has only in a Silver color. Both have the pulley cage made of aluminum plates for the front and the back. (Remember the XT uses a steel plate to create the rear most part of the pulley cage.) The XTR group, was the first 8 speed system designed for mountain bikes, this is for use as a 6, 7, or 8 speed rear derailleur and is STI compatible. All the linkages and the pulley cage are made of aluminum to reduce weight. The XTR uses a 5mm allen wrench to mount and fasten the derailleur cable. The cable fastening bolt on both the XT and the Dura-Ace rear use a separate nut that is replaceable for the bolt to fasten to. The link pins fastening the left and right links to the derailleur body, and the mounting bracket/mounting bolt assembly are sealed, (using small recessed plates) against contamination, to reduce friction. The high and low gear cam adjustment screws are on the left side requiring a small Phillips screwdriver for adjustment. There is also a "B-tension" adjustment screw that moves the entire rear derailleur front to back to add tension to the chain. The XTR also has an adjustment screw for the return spring which adjusts the force used to push the derailleur back from the high to the low geared cog. The convenience adjuster, (this permits you to adjust, without tools, the cable tension as the cable stretches), is easy to grip with a large grey plastic jacket around a steel bolt, with detent at each quarter turn. The guide pulley on the XTR uses a ceramic bushing for the "bearing assembly" that it revolves on. At the core of a nylon-like pulley a white ceramic outer sleeve is pressed into it. Inside this outer sleeve, a greased inner ceramic sleeve slides. The ceramic assembly is surrounded (both front and back) with a rubber gasket that has a stamped aluminum plate in the shape of a cup to shield the guide pulley from dirt contamination. The tension, (or idler pulley), actually has a precision sealed cartridge bearing. This is the first occasion for Shimano, even the Dura-Ace rear doesn't include precision sealed pulley bearings. The pulley cage includes several levels of protection against spoke damage from an overshift. Caution, on the XTR rear, the cable fastening bolt threads into a tapped hole on the body. If you over-tighten this bolt and strip the threaded body there are no replacement provisions, nor is there space for a small after market nut, replacing the derailleur would be necessary. The steel mounting, pivot and pulley bolts can be replaced with SRP Titanium versions and are writen about at the end of this article. Described by Shimano as "middle cage" length, the XTR rear will accept cogs up to 32 teeth in size and is rated at a 33 tooth capacity. It weighs 225.5 grams. Made in Japan. $ Price in Catalog

This is by far the most requested, quality rear derailleur today. It uses the Shimano Double Servo-Panta Mechanism. Shimano put everything in this little wonder, and it has many high performance features. It is Shimano Total Integration (STI) compatible, and can be used as a 6, 7 or 8 speed derailleur. Serious users may notice the 1994 m737 XT changer lacks the adjustable return spring, found on last years model, which adjusts the amount of pressure used to shift the chain back to the high gears. It's not clear why this was omitted but possibly it will find its way back on a future model as an "enhancement". There is a "B-Tension" adjuster that permits you to adjust the tension of the mounting spring, and how the entire derailleur supports the chain. The convenience adjuster, (this permits you to adjust, without tools, the cable tension as the cable stretches), is easy to grip with a large Grey plastic jacket around a steel bolt, with detent at each quarter turn. The link pins fastening the left and right links to the derailleur body, and the mounting bracket/mounting bolt assembly are sealed against contamination, to reduce friction. The XT rear derailleur has what Shimano calls "sealed" pulleys. These pulleys use a series of channels cut into the pulley and seals, but they do not use "precision sealed bearing cartridges". Precision sealed bearing cartridges are commonly called "sealed bearings". The linkages are made of aluminum, with the mounting and pivot bolts made of steel. The pulley bolts are made of steel and the pulley cage has the plate nearest the bike made of steel with protection against spoke damage from an overshift, while the outer plate is made of aluminum. This derailleur comes in a middle cage model called a "GS" or a long cage model which is called the "SGS". The SGS model weighs 235 grams. The SGS will accept cogs up to 32 teeth in size. The "GS" model is rated at a 28 tooth capacity. The XT rear is made of aluminum with plastic pulleys. A 5mm hex wrench will tighten both the cable fixing bolt and the mounting bolt. The steel mounting bolt and the pulley bolts can be replaces with lighter weight Titanium versions found at the end of this article. The pivot bolt isn't replaceable, the pieces at the pivot are permanently pressed (peened) together

M737 XT Long Cage "SGS"     $ Price in Catalog
M737 XT Middle Cage "GS" $ Price in Catalog 

The Shimano M563 Deore LX rear is new for 1994 and comes as a SGS model with a super long cage. It is an STI compatible unit, that can be used for 6 or 7 speed index shifting (SIS) and is capable of 8 speed shifting with the new 8 speed LX equipment. The LX has aluminum linkages, with a steel mounting bolt, as well as an all steel pulley cage and pulley bolts. This derailleur has sealed link pivots and a sealed mounting bracket (which includes the mounting bolt and spring). This 291.5 gram derailleur shifts on the fly, quickly and smoothly thanks to a Double Servo-Panta mechanism and what Shimano calls a "Centeron" guide pulley. It has a "B-tension" adjustment screw that moves the entire rear derailleur front to back to add tension to the chain. This version of the LX lacks the adjustment cam/bolt for adjusting the return spring which was on the 1993 model. The return spring design has been changed and it seems the new coiled spring may be capable of this previous feature. The convenience adjuster, (this permits you to adjust, without tools, the cable tension as the cable stretches), is easy to grip with a large Black plastic jacket around a steel bolt, with detent at each quarter turn. A 5mm hex wrench will tighten the cable fixing bolt and the mounting bolt. The LX has Black aluminum alloy, and a chromed steel cage. Maximum rear cog is 32 teeth, while the total capacity is 38 teeth. The Mounting and pulley bolts are capable of being replaced with Titanium versions found at the end of this article. The pivot bolt is incapable of being changed. It is pressed permanaently, (peened) holding the linkages and pulley cage together. The M563 weighs 291.5 grams. $ Price in Catalog

The STX is the inexpensive replacement at the bottom of the mountain parts line of parts as the LX group has been elevated in price. This model is made a Special Edition by brown colored Black chrome plating on the outer cgae plat end the outer body link. It also has recessed hex head pulley bolts rather than the simpler six sided steel bolts. The left and right linkages are made of forged aluminum. The body links pieces, both front and rear are stamped from sheet steel. The front piece is Chromica (brownish Black chrome plating) and the rear piece is painted Black. The inner plate of the pulley cage is paineted Black, the outer plate has a Chromica finish. The same pulley found on the LX are also used here. They use a steel bushing within a plastic wheel with channels and stamped steel dust caps to seal the pulley. The SRX can be used as a 6, 7, or 8 spped rear changer. It has B-tension adjustment. The convenience adjuster, is easy to grip with a large Black plastic jacket around a steel bolt, with detent at each quarter turn. A 5mm hex wrench will tighten the mounting bolt onto the frame. The shift cable is held to the STX by a bent steel plate that is compressed against the body by a 9mm steel nut. The STX SE is made in two cage versions, a long cage SGS and a short cage GS model. Maximum rear cog is 32 teeth on the long cage SGS, and 28 teeth on the short cage GS. Total capacity is 38 teeth (super long cage-SGS), and 28 teeth (short cage-GS). The SGS model weighs 284.5 grams

STX SGS - long cage $ Price in Catalog
STX GS - short cage $ Price in Catalog