rear derailleur woes....(possibly)

[suer]

My 15 year old Roberts touring bike had the chain start jumping on the
big chainring but not on the middle chainring. Big chainring was
shark-toothed and incidentally so was middle chainring. (Campag ATB
Record).

I've just fitted new TA Campag-pattern middle and big ring (last night,
fiddly job having to also unbolt the little chainring allen-bolts too).

Chain and sprockets have been replaced over the years a few times.

But even with new chainrings, it still slips horribly on the big
chainring if I push down hard on the pedals, yet is well-behaved on the
middle chainring.

I suspect the rear Campag mech has a broken spring or summat...is there
a diagram anywhere of what a Campag Record rear mech should look like,
components-wise.

It is making a "tick-tick" noise and flicking slightly forwards with
each tick too, which it didn't used to do. Hence why I suspect a spring
has broken so it's not able to tension big gears (big ring) only medium
and small gears (middle ring and, if I were to find a 1-in-5 hill, small
ring).

The chainrings needed replacing anyway.

Cheers,

 

[Rob Morley]

On Fri, 06 Jun 2008 18:05:00 +0100
suer <[email protected]> wrote:

> My 15 year old Roberts touring bike had the chain start jumping on
> the big chainring but not on the middle chainring. Big chainring was
> shark-toothed and incidentally so was middle chainring. (Campag ATB
> Record).
>
> I've just fitted new TA Campag-pattern middle and big ring (last
> night, fiddly job having to also unbolt the little chainring
> allen-bolts too).
>
> Chain and sprockets have been replaced over the years a few times.
>
> But even with new chainrings, it still slips horribly on the big
> chainring if I push down hard on the pedals, yet is well-behaved on
> the middle chainring.
>
> I suspect the rear Campag mech has a broken spring or summat...

It seems more likely that you need a new chain, and probably
freewheel/cassette too.

 

[Paul Boyd]

On 06/06/2008 18:05, suer said,

> But even with new chainrings, it still slips horribly on the big
> chainring if I push down hard on the pedals, yet is well-behaved on the
> middle chainring.

I would go along with Rob - your chain is knackered. If it's got to the
stage you describe, I would suggest a new chain and cassette. I don't
think you'll find there's anything wrong with the derailleur.

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[POHB]

On 6 Jun, 19:31, Paul Boyd <[email protected]> wrote:
> I would go along with Rob - your chain is knackered.  If it's got to the
> stage you describe, I would suggest a new chain and cassette.  I don't
> think you'll find there's anything wrong with the derailleur.

Easy enough to check with a ruler, have a look at "Measuring Chain
Wear" here http://www.sheldonbrown.com/chains.html

 

[suer]

In article <20080606182656.240cd35b@bluemoon>,
Rob Morley <[email protected]> wrote:


> It seems more likely that you need a new chain, and probably
> freewheel/cassette too.

Indeedy, the chain proved to be the culprit.

New chain and sprockets, all running hunkydory now, and just been
well-tested in a week of Dartmouth/Dawlish/Haldon Forest hills. No
slippage or jumpage. Thanks!