rear derailleur cage

[Doyleyburger]

Very inexperienced question here....

How do I determine the cage size on my rear derailleur ?
Looking at them online and there seem to be a couple of sizes.
Incidentally why is it called a cage?

 

[twentysix by twentyfive]

Not sure about the name but the size depends on the number of teeth of sprocket and chain ring size you need to accommodate. Basically - how much chain do you have to keep tensioned over all the gears you have. Usually if you use a triple chain set then you'll need a medium to long cage size.

I suppose the cage is that which encages the jockey wheels.

Is that correct folks?

 

[RecordAceFromNew]

How do I determine the cage size on my rear derailleur ?

Centre to centre of jockey wheels. This is a little out-of-date but it will give you the idea.

 

[slowmotion]

Not sure about the name but the size depends on the number of teeth of sprocket and chain ring size you need to accommodate. Basically - how much chain do you have to keep tensioned over all the gears you have. Usually if you use a triple chain set then you'll need a medium to long cage size.

I suppose the cage is that which encages the jockey wheels.

Is that correct folks?

Yes

 

[Cyclopathic]

It's called a cage because it was invented by the actor Nicolas Cage.

 

[Doyleyburger]

It's called a cage because it was invented by the actor Nicolas Cage.

Ah that makes sense now

 

[Shut Up Legs]

Not because it reminds one of being trapped inside a car?