rear derailleur question

Richard Slay said:

I've got an 02 Specialized Enduro Pro with an XT rear derailleur. I

managed

Quoted message said:

to break it on my last ride. I've been looking on eBay for a

replacement

Quoted message said:

and see the different cage lengths. Can someone tell me the purpose

for the

Quoted message said:

different lengths?

The purpose of the different cage lengths on rear derailleurs is to
take up varying amounts of chain depending on how large a spread you
have between your front chainrings and rear cogs. If the rear
derailleur is not able to take up the chain slack, then the chain will
droop in the smaller cogs. A drooping chain could lead to problems if
it slaps around on bumpy roads and derails from the pulleys or
chainrings. In theory the longer the cage the less quick the shifting
in the rear. Theory. In practice I've never noticed any difference
between a short and long cage rear derailleur.