Vintage Campy Super Record Drive Train Question

Wildbears

I'm putting an old Campy Super Record gruppo (1980) onto a vintage Trek 970 frame. The chain rings are 42 and 52. The cassette is an 8 speed, 12-25. The RD has a short cage and has a listed chain wrap capacity of 26 and a maximum cassette cog size of 28.

Not sure what's going on but the chain "hangs down" loosely between the crank and the RD when on the 12t cog and the 42t chain ring but the RD is at its max stretch when the chain is on the 25t cog and 52t chain ring.

There is some but not severe chain ring wear. Doesn't seem like this would be enough to do this.

I can take 2 links out of the chain but that would preclude using the 25 x 52 combo. Maybe that's the way it was designed. With a 12-28 cassette, it would also preclude use of both the 25t and 28t cogs.

If this is the way the RD was designed to be used, back in the day, would the use of a RD hanger extender help? Another option is to go to a 12-23 cassette.

Note: The only adjustments on this derailleur are for inner and outer travel limits.

me-109

Sounds like a slightly tired cage tension spring in the rd. If ok on the next year up I wouldn't worry,. You wouldn't normally be using it in the extreme cross-chained gears.

Wildbears

Thanks for the suggestion. I thought about that too and checked the spring action. It's working as it should! Very strong.

Wildbears

Note that this RD does not have an "angle-adjustment screw". That would work to solve the problem.

trevor.hall12

Campag RDs are quite fussy when it comes to chains
The pic is in small front and rear

Wildbears

Using this formula: chain-wrap = (large chain ring - small chain ring) + (large rear cog - small rear cog).

For 52/42 chain rings and a 12-25 cassette: (52 - 42 = 10) + (25 - 12 = 13) = 23-tooth chain-wrap.

As mentioned, specifications for this RD indicate a maximum chain wrap capacity of 26.

?????

Ben6899

Do you have photos, which you can share?

Wildbears

I'll take some later today and post.

Wildbears

I'll get some measurements also...

trevor.hall12 said:

Campag RDs are quite fussy when it comes to chains
The pic is in small front and rear

webboo

Free hub dragging?

Wildbears

Thanks. Checked and no drag.

webboo said:

Free hub dragging?

Wildbears

The RD is a Campagnolo Super Record (steel version without titanium pivot bolts), 4001, Super Record (2nd gen, matte finish-2nd ver of 2nd
gen):

There is a retention/stop pin that limits how far the derailleur can fold upon itself and keeps the tension spring from unwinding when the derailleur is off the bike.

When inserted it also does not allow collapse to anywhere near 8-15 mm that is recommended for subsequent Campy RD models.

The closest approach is 25 mm, when in place, and it looks like a 12-23 is the largest cassette that works well with the large (52t) chainring.

Although removal allows the derailleur to fold onto itself further and attain an 8-15 mm gap, this does not assist in using a larger cassette range such as a 12-28t.

While a maximum sprocket size of 28t is listed in the specs, shifting onto the 25t and 28t sprockets is not possible when on the large, 52t chainring.

See 1st pic which shows maximum collapse with the pin inserted (screwed in):



Pin...



Inserted....

Wildbears

Thanks to everyone who posted to this thread.

Ben6899

Glad you sorted it! Do we know what the pin is supposed to achieve (other than a slack chain)?

Wildbears

The pin limits the collapse of the RD mechanism and prevents the spring from becoming unwound when off the bike.

The former is how far up the lower jockey wheel can approach the cassette. When the pin is in, the "H" measurement is limited to 25 mm of separation (see "H" in the diagram posted above by Trevor).

Without it, collapse can be adjusted by chain length to be much less at 8 to 15 mm.

HOWEVER this does not change the maximum sprocket size limit on this RD model.

The 8-15 mm range is what Campy recommends for RD models that followed this one.

Wildbears

The above post was edited to correct some of the listed information.

MattFalle

DRWILBERS said:

The above post was edited to correct some of the listed information.

groovy penne✌️✌️✌️

tourdriving

DRWILBERS said:

The RD is a Campagnolo Super Record (steel version without titanium pivot bolts), 4001, Super Record (2nd gen, matte finish-2nd ver of 2nd
gen):

There is a retention/stop pin that limits how far the derailleur can fold upon itself.
When inserted, as it has been until now and its discovery, it does not allow collapse to anywhere near the recommended 8-15 mm. The closest approach is 25 mm, when in place, and it looks like a 12-23 is the largest cassette that works well with the large (52t) chainring.

Removal allows the derailleur to fold onto itself and thus attain the 8-15 mm gap suggested for proper chain length and the ability to work with a 12-28 cassette/26t chain wrap.

See 1st pic which shows maximum collapse with the pin inserted (screwed in):



Pin...



Inserted....

the pin is to hold the spring tight, you can tighten the spring when pin is out

tourdriving

Wildbears

I just discovered that function!

With the derailleur off of the bike and the chain out, the spring can unwind just short of one turn.

When re-inserting the pin, the spring has to be re-wound ~ one revolution, otherwise there is insufficient "pull" on the chain and the derailleur will not function properly.

The first part of the pin is not threaded. This allows easy insertion with correct tension on the spring.

Many thanks for correctly pointing out the purpose of the pin.

tourdriving said:

the pin is to hold the spring tight, you can tighten the spring when pin is out

tourdriving

DRWILBERS said:

Note that this RD does not have an "angle-adjustment screw". That would work to solve the problem.

you had seen there are 2 holes in the outer plate for the spring

Wildbears

Yes.

There are also two holes in the spring cover plate!

Are these there so you can adjust spring tension???

The end of the spring extends thru these holes.



With 4 holes, would that give you a choice of 4 different spring tensions??

tourdriving

DRWILBERS said:

Yes.

There are also two holes in the spring cover plate!

Are these there so you can adjust spring tension???

The end of the spring extends thru these holes.



With 4 holes, would that give you a choice of 4 different spring tensions??

don`t remember, but if you are on twitter ask this man @TheCampagKid

Wildbears

The tip of the installed spring will only fit thru one pair of holes. The second pair of holes are of too small diameter.

Ben6899

DRWILBERS said:

The pin limits the collapse of the RD mechanism and prevents the spring from becoming unwound when off the bike.

The former is how far up the lower jockey wheel can approach the cassette. When the pin is in, the "H" measurement is limited to 25 mm of separation (see "H" in the diagram posted above by Trevor).

Without it, collapse can be adjusted by chain length to be much less at 8 to 15 mm.

HOWEVER this does not change the maximum sprocket size limit on this RD model.

The 8-15 mm range is what Campy recommends for RD models that followed this one.

Thanks for sharing!