Derailluer cage length


Rural Quebec
The longer the cage the bigger the cog it can handle.
The longer the cage the more vulnerable it is.
Loch side.
The longer the cage, the bigger the range it can handle. Range is determined by the difference between the biggest and smallest sprocket combinations and expressed in a number that represents teeth.

For example: My roadbike has a 52/39 combination in front and a 11-23 at the back. The range here is (52-39) + (23-11) = 13 + 12 = 25.

My mountainbike has a 44/32/28 combination in front and 12-28 at the back. The range here is (44-28) + (28-12) = 16 + 16 = 32.

On the roadbike a short cage is sufficient and on the MTB a long cage is imperative.

Long cage can handle short ranges but short cages can't handle long ranges.


as ayceejay said above longer cages are more vulnerable in a accident; also, it’s possible that a short cage would be stiffer and hence may get a more positive shift and potentially lighter in weight.
I thought the cage was the cuboid bit with the spring inside, if so then surely that is no more or less vulnerable whether it is the short or long version?
The cage is the section which holds the jockey wheels; the bit with the spring in is the Parallelogram movement.

EDIT - Bu88er too slow, like my old school reports "must try harder"


The short cage will give crisper gear changes. The long (or possibly medium) cage is required if you have a triple chainset or a compact double with a wide range cassette e.g 11-32, in order to handle the large differences in tooth counts between the highest and lowest gears.
Loch side.
The cage length has nothing to do with how quickly (crisply if you want), the gears change. That's because gear change is determined by the position of the guide pulley on the vertical axis with the sprockets and, the distance between the guide pulley and sprocket that's being changed to and from. Both long and short cages can be set to the same distances and are supposed to be set to the same distance via the B-tension adjustment.
A longer cage has potential for more chain slap and the chain jumping off the front chainring in very rough conditions. The long chain and wide variance in tension being the prime cause.

On most road bikes you simply don't need the range of gears and therefore the cage can be shorter as well as the chain. On triple chainring setkups you need the larger variance, hence longer chains.


Rollin' along
Manchester way
why not all use long cages?
I have a long cage on my roadie. The rear mech was kaput when I bought it and I had an idea I was going to put a more easygoing cassette range on it next payday for my knees, so went long in anticipation. Found I was happy enough with the road ratio's tho so never bothered with the cassette change.

@Fifelad, I don't notice any difference in smoothness, changing, need to adjust etc having a long cage on a short gear range
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