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Rear Derailleur


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Can some please explain to me what is meant by "Maximum Front Difference: 22T" and "Total Capacity: 37T" and lastly "SS/GS" when the specs of a rear derailleur are given.


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This refers to the capacity of a derailer.


For instance, if you had a crank with one 52 and one 44 tooth ring, the difference in teeth would be 8.


If you had a triple crank and your big ring was 44 and the smallest one 28, the difference would be 16. If the derailer's capacity (That number you quoted) was larger than the difference above, the derailer is said to have enough capacity to handle the difference.

In other words, you cannot use a combination on the example you cited that gives you a difference bigger than 22.


The same goes for the rear derailer. If your largest sprocket is a 28 and the smallest an 11, then the difference is 17. Your jockey should have a capacity of at least 17 or a bit more.


The total capacity is the sum of the front and rear difference. For instance, if you have a combination of 11-28 at the back and a 44-28 in front, you'll need a jockey that can handle at least 33 (17+16).


The longer the jockey cage, the larger its capacity. If you exceed its capacity, it stretches too far forward when you are in the biggest of your front and rear sprockets and it will not take up the chain slack on the return run in the smallest two sprockets front and rear.


Shimano's capacity ranges are conservative and you can push them a bit.



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