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PostPosted: Thu Aug 16, 2018 11:21 am 
Retro Guru
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Joined: Sun Jul 25, 2010 12:22 pm
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Location: Somewhere in the mid '80s..
I've had this problem before - can anyone help/ remind me how to solve it??

The top of the nearest jockey wheel cage rubs the second sprocket when the first sprocket is selected. If you rotate the rear mech clockwise by hand this stops, but of course the rear mech rests in this position against the hooked tag formed into the Campag dropout itself.

The lowest gear is a 24t with the second being a 22t and this is the one that the rear mech is fouling.

I'd considered filing the top area of the jockey cage down to a minimum but that seems a bit sacreligious!

Any ideas?

Image

Thanks,

Craig


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PostPosted: Thu Aug 16, 2018 11:36 am 
Old School Grand Master
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Joined: Fri Oct 14, 2011 8:41 pm
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Location: Cumbria
Blimey that looks all brand new :). Is the chain on the big ring at the front?


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PostPosted: Thu Aug 16, 2018 11:37 am 
Old School Grand Master

Joined: Mon Feb 11, 2008 9:42 am
Posts: 3332
Pull the wheel back a couple of mm?

That'll pull the freewheel away from the mech and pull the chain slightly tighter, which will move the cage slightly round it's pivot. Giving you more clearance.


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PostPosted: Thu Aug 16, 2018 11:38 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 9371
Location: New Forest, UK
I have similar issues with a far later setup. Like you my frame has a very short drop on the mech hanger, although with a vertical dropout. My solution was one of those cheap mech droppers.
https://www.sjscycles.co.uk/gear-spares ... -extender/


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PostPosted: Thu Aug 16, 2018 11:40 am 
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Location: Somewhere in the mid '80s..
mattr wrote:
Pull the wheel back a couple of mm?

That'll pull the freewheel away from the mech and pull the chain slightly tighter, which will move the cage slightly round it's pivot. Giving you more clearance.


GAWD!! Could it really be as simple as THAT??! I never even thought of that idea!! :facepalm:

I'll pass it on to my pal - I built the bike for him from mostly NOS/ VGC parts recently, but this issue has been bugging him since!

Many thanks!!

Craig


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 Post subject: Re:
PostPosted: Thu Aug 16, 2018 1:20 pm 
Retro Guru
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Joined: Mon Sep 24, 2012 9:10 pm
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Quote:
. Is the chain on the big ring at the front?


In that photo? I doubt it. If it is, the chain is way too long.
I think the chain must be on the small ring in that photo.

Quote:
Pull the wheel back a couple of mm?

That'll pull the freewheel away from the mech and pull the chain slightly tighter, which will move the cage slightly round it's pivot. Giving you more clearance.


I agree about pulling the wheel back, but I reckon if that fails, making the chain looser- putting two more links in it- might help to alleviate the problem, provided that the spring is still tensioning the chain when on small ring/small sprocket.


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 Post subject: Re:
PostPosted: Thu Aug 16, 2018 6:19 pm 
MacRetro rider
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Location: A Fifer furth o' the Kingdom
All my knowledge of rear mechs, bike bits in general, is with Shimano MTB stuff and lately Ultegra on my road bikes so no idea if Campag is different. With that said, it looks to me that the chain is over-wrapping on the cog, the top jockey wheel is too high. My experience is the chain angles down or is horizontal as it moves to top jockey wheel not up. Wouldn't tightening the B-tension screw not rotate the mech down and backwards therefore give the mech cage more clearance to cogs? Moving wheel backwards in dropouts may give more clearance but would it stop the over-wrapping of chain?
Just did a wee search online and most of pics of rear mechs/cassette/chain is same as my experience, chain angles down to top jockey wheel.


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PostPosted: Thu Aug 16, 2018 9:11 pm 
Old School Grand Master
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Joined: Fri Oct 14, 2011 8:41 pm
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Location: Cumbria
Pull the chain tighter and see if that swings the cage back and down a bit. Campag changed the cage over the years to get it to run from 22 to 26 in the end, maybe its an old NR cage on a younger SR body?


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 Post subject: Re: Re:
PostPosted: Thu Aug 16, 2018 9:45 pm 
Old School Grand Master

Joined: Mon Feb 11, 2008 9:42 am
Posts: 3332
old_coyote_pedaller wrote:
Wouldn't tightening the B-tension screw not rotate the mech down and backwards therefore give the mech cage more clearance to cogs?
Don't think campag mechs of this vintage have b-tension adjustment. Just a fixed tab.


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PostPosted: Thu Aug 16, 2018 9:50 pm 
Old School Grand Master
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Joined: Fri Oct 14, 2011 8:41 pm
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Location: Cumbria
Just had a look at some pics and the cage looks right for the second gen SR in the OP.


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