Campagnolo rear derailleur help required

pilot_pete Posts: 2,120
edited September 2011 in Workshop
Got a problem with my 2009 Centaur short cage rear derailleur today. To be honest it has never been great, but today it has just gone completely off.

The problem is this. No matter how I adjust the 'H' screw (page 40 in this manual I cannot get the upper pulley to the specified ~7mm (same page in the manual above) This has lead to the cage being too close to the largest cog on the cassette (19-25) Prior to today you could hear a rumble when in first gear when putting the power down, which is the upper roller 'squeezing' the chain up too tight to the first gear cog. This I have lived with, but today a further problem has manifested. When I changed to second gear, the inner cage itself is now touching the biggest cog. Changing to third and subsequent gears the problem goes away, so it is only when in the second cog.

This would appear again to be a consequence of the upper pulley being too close to the cogs. But like I have said, no matter how I adjust the 'H' screw, this distance doesn't change.

I have a Record 10speeed chain, which is as supplied with the bike (a Pinarello FP3), so assume that it has the correct number of links, but using the various calculator methods available, the length does come out one link less than I have fitted. However, removing my split link and moving the chain around the big ring to simulate one link less does leave the derailleur very 'stretched' forwards on 'big/big'. So, I think the chain is the right length, and it seems to make no difference to the clearance of the top pulley to largest cog.

Now if I am correct, the 'H' screw sdjusts the tension of spring RD-RE008 (page 26 of the spares catalogue This works against the RD-RE017 in the same picture, which should pivot the derailleur body around the RD-CH119 derailleur mounting bolt, thus adjusting the top pulley to cog distance.

This is not happening, so my guess is that one of the springs, probably RD-RE017 is not working properly/ broken as the derailleur doesn't pivot around when adjusting the 'H' screw, it is only the cages that pivot around their pivot point, so the screw is actually moving the little ratchet as designed.

This is very frustrating so any insight would be great. Thanks in advance.


p.s. the indexing is spot on.....