Clunky rear derailleur on lower gears

[Tin Pot]

A bit of a puzzler.

On the smallest four cogs the rear derailleur is smooth.

On the cogs larger it immediately is clunking, juddering.

Recent history: Reindexed it last week, did some hills in the rain noticed it not shifting properly, did a turbo session with it clunking weirdly (tried to stay in smooth gears). Bike is on the turbo in the garage mostly, used three to four times per week.

Alignment pics
Good:

Bad:

The whole derailleur starts juddering.

Can't upload the video

 

[Yellow Saddle]

Your B-tension screw mounting has broken off and now the pulley teeth connect the cassette teeth through the chain on the bigger sprockets.

 

[winjim]

I would check the B-screw, or whatever Campagnolo call their system that isn't a B-screw setting. Got any side-on pics in large and small sprockets?

 

[S-Express]

As YS says - B screw appears to be missing. If the boss has broken off, then it's time for a new rear mech.

 

[Tin Pot]

I'm not sure where the B screw is on Campag Veloce:

https://www.campagnolo.com/media/immagini/2062_n_rear-der-veloce-silver-slide2.jpg

 

[mjr]

See https://www.cyclechat.net/threads/veloce-b-tension-adjust.33153/ (it doesn't have a B screw - another rare YS error for my bookmarks )

 

[Tin Pot]

Thanks, but the linked thread has a bunch of dead links.

I seem to recall the H screw, I'll find my campag manual. If something has broken of, it's something I've never adjusted.

 

[Tin Pot]

Is it this one?

 

[winjim]

Is it this one?

View attachment 342367

Yes

 

[Tin Pot]

Yes

Great I'll play around with it but it doesn't seem to do anything so far.

 

[Yellow Saddle]

Great I'll play around with it but it doesn't seem to do anything so far.

Yes, that's the one. It's a subtle little device but what it does is to increase/decrease the distance between the guide pulley and the sprockets so that they don't touch through the chain. It is only effective in the bigger sprockets since in the smaller ones, the RD's spring pulls the pulley away from the cassette.

It may be obvious once you've cured the bike of the pervasive siphilitis and you can see what's what.

 

[Yellow Saddle]

See https://www.cyclechat.net/threads/veloce-b-tension-adjust.33153/ (it doesn't have a B screw - another rare YS error for my bookmarks )

Pssst! How much do you want from me to press the delete button on that little black book(mark) of yours?

 

[Tin Pot]

Okay loosening it completely so it's nearly falling out has given me two more gears, but no more.

It's not clear to me what it is loosening, can it be replaced? Could whatever it is require lubrication?

I've had a variety of problems with my bike since using it on the turbo on the garage regularly, with salt forming and cables sticking.

 

[Tin Pot]

Yes, that's the one. It's a subtle little device but what it does is to increase/decrease the distance between the guide pulley and the sprockets so that they don't touch through the chain. It is only effective in the bigger sprockets since in the smaller ones, the RD's spring pulls the pulley away from the cassette.

It may be obvious once you've cured the bike of the pervasive siphilitis and you can see what's what.

Are you saying that cleaning the shi... off might fix it?

 

[mjr]

Pssst! How much do you want from me to press the delete button on that little black book(mark) of yours?

That's still not a B screw.