Derailleur Size

On Tue, 27 Jul 2004 19:06:40 -0400, "pjx" <[email hidden]>

Quoted message said:

What is meant by "Short Cage." I am not sure what I have, so I need to
know how to tell the difference.

Standard cage is a better term. The others might be referred to as
medium or long cage.

Paul

Thanks for the reply but I am still not sure what I have. Is there a
measurement that I can take? I am planning on replacing it with a better
one

Paul
"Paul Kopit" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Tue, 27 Jul 2004 19:06:40 -0400, "pjx" <[email hidden]>

Quoted message said:

What is meant by "Short Cage." I am not sure what I have, so I need to
know how to tell the difference.

Standard cage is a better term. The others might be referred to as
medium or long cage.

In article <[email hidden]>,
"pjx" <[email hidden]> writes:
|> Paul
|>
|> Thanks for the reply but I am still not sure what I have. Is there a
|> measurement that I can take? I am planning on replacing it with a better
|> one
|>
|> Paul
|> "Paul Kopit" <[email hidden]> wrote in message
|> news:[email hidden]...
|> > On Tue, 27 Jul 2004 19:06:40 -0400, "pjx" <[email hidden]>
|> > wrote:
|> >
|> > >What is meant by "Short Cage." I am not sure what I have, so I need to
|> > >know how to tell the difference.
|> >
|> > Standard cage is a better term. The others might be referred to as
|> > medium or long cage.
|>
|>

The choice of derailleur cage length is based on 2 factors:

1. The largest rear sprocket you will use
2. The "Chain wrap capacity", which is defined by the formula below.

Chain Wrap = (large chainring - small chainring)+(large rear cog - small rear cog)

So if you have 53/39 on the front, and 13-26 on the rear for instance, your chain wrap
will be: (53-39) + (26-13) = 27.

All rear derailleurs are rated by the manufacturer with limits on the above 2 numbers. They
will tend to be conservative, so you can stretch them a little if you don't abuse your gear.

Hope that helps,

Gareth