# Shimano XTR Rear Derailleur RD-M971-SGS vs GS



## jw8725 (Jun 12, 2009)

Hi please can someone help?

Can you explain the difference between Rear Derailleur RD-M971-SGS 

and

Rear Derailleur RD-M971-GS

Which one would benefit climbs?


----------



## Garlock (Jul 9, 2008)

*[GS] High normal or top normal *rear derailleurs return to the smallest sprocket on the cassette when no cable tension is applied.[8] Most Shimano mountain, all Shimano road, and all SRAM and Campagnolo derailleurs are high-normal designs.

*[SGS] Low normal or rapid rise* rear derailleurs for mountain bikes are manufactured by Shimano. These derailleurs, introduced in 2004 in the XT and XTR groups maintain position over the largest sprocket on the cassette when no cable tension is applied.[9] On mountain bikes especially, this is an advantage because gear changes tend to be easier and quicker when changing in the spring weighted direction. Changing gears in the sprung direction requires only a light click on the control, and the spring will move the derailleur into place. In road racing the swiftest gear changes are required on the sprints to the finish line, hence high-normal types, which allow a quick change to a higher gear, have become the most common. In off-road cycling the most critical gear changes occur on difficult uphill sections when the rider must not only cope with the hard pedaling, but must also get into a critical riding position to maintain grip and must often cope with obstacles and difficult turns at the same time. In addition, they may be moving at a slow speed and it may be difficult to ease off pressure from the pedals without losing balance. Under such conditions being able to switch easily to a lower gear can make the difference between being able to tackle the section or having to get off and push, and thus the advantages of low-normal changers make them the best choice. From a user interface point of view, they shift opposite to other rear derailleurs. The user 'clicks' the index finger trigger to move to a larger sprocket, and pushes with the thumb trigger to select a smaller sprocket.


----------



## kapusta (Jan 17, 2004)

jw8725 said:


> Which one would benefit climbs?


No difference in how the bike climbs.


----------



## gmcttr (Oct 7, 2006)

The RD-M971-SGS and GS are both "top normal" derailleurs. The SGS and GS refers to the cage length and indicates total capacity (how much chain they can take up). The SGS is the long cage and can take up more chain. See this thread for additional information.

The RD-M*970*-GS and SGS are the low normal derailleurs.


----------



## FujiRich (Jun 5, 2009)

didnt even know about low-normal derailleurs until now although i was wondering about the difference between these two and the whole cage length question...cheers guys!


----------

