Rear derailleur

[Myosmith]

Are rear derailleurs set up for a specific number of cogs or is the travel determined entirely by the shifter? What I am wondering is will a Shimano derailler from a bike with a 5 cog cassette work on a bike with a 7 cog cassette if I use the 7 speed shifter?

[socialfox1]

(05-10-2011, 12:08 PM)Myosmith Wrote:  Are rear derailleurs set up for a specific number of cogs or is the travel determined entirely by the shifter? What I am wondering is will a Shimano derailler from a bike with a 5 cog cassette work on a bike with a 7 cog cassette if I use the 7 speed shifter?

Probably, as long as you set up the H and L limit screws to not run into the spokes or frame. Though I have heard different shifters and different derailleurs don't function well.

[cyclerUK]

It will have to be trial and see.
You don't need to fit the chain.
Just fit the derailleur and cable and try it.
The derailleur jockey wheel should line up directly under each sprocket for every click of the shifter.