Rear Derailleur Wear

How do you know when a rear derailleur needs replacement? Mine still shifts ok but I've learned that
doesn't mean that a new part wouldn't improve performance.

My experience with cassettes is that they seem to work ok but when I put a new one on, it's
much crisper.

 

I have replaced two that wore out. Their return spring would not pull the thing back quickly, e.g.
it stuck. They also won't spin smoothly around their pivot.

-Dion

"Paul Kopit" <[email protected]> wrote in message
news:[email protected]...
> How do you know when a rear derailleur needs replacement? Mine still shifts ok but I've learned
> that doesn't mean that a new part wouldn't improve performance.
>
> My experience with cassettes is that they seem to work ok but when I put a new one on, it's much
> crisper.

 

my 9.0SL eventually got so sloppy that it wouldn't hold a gear under power - grrrr the X.0 is built
so that you can tell when it is worn out. "A Muzi" <[email protected]> wrote in message
news:[email protected]... "Paul Kopit" <[email protected]> wrote in message
news:[email protected]...
> How do you know when a rear derailleur needs replacement? Mine still shifts ok but I've learned
> that doesn't mean that a new part wouldn't improve performance.
>
> My experience with cassettes is that they seem to work ok but when I put a new one on, it's much
> crisper.

Gear changers normally degrade along a continuum and, you're right, one often does not notice the
incremental loss of crispness in shifting.

You can get a good idea of this wear by holding the lower pulley area and moving the bottom of the
cage laterally back and forth. Note when you do that the play will be distributed through the lower
pivot, the body's rivets and the upper pivot. This sideplay is what makes for a sloppy shift, that
and wear of pulley sleeves, cassette cogs and chain.

This simple test will have some meaning if there are a few new and old bicycles nearby with similar
equipment. Even a new part has some side play.

That being said, modern changers can be pretty far gone and still work.
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971