Will Super Record 12 run a Chorus 11-34 cassette?

[clarendon]

Looking to get a cassette for a pair of climbing wheels and thinking to pair the Chorus 11-34 cassette with a mechanical SR12 RD. The Campy website seems to suggest the 11-34 cassette will work, but the technical info download on the same page doesn't list it, and some retail sites suggest the 11-34 only works with the Chorus 12 RD. Anyone know what the answer is?

https://www.campagnolo.com/US/en/Components/super_record_sprockets
https://www.merlincycles.com/campagnolo-chorus-cassette-12-speed-165760.html

[thirdgenbird]

I am nearly sure record and super record only went 32t at launch and then was updated to 34t when chorus came out. The cage should be marked on the back to identify it.

[Mark McM]

I haven't tried 12 speed derailleurs, but my 11spd Record derailleur (2015+) can handle a 34 tooth sprocket. 12spd derailleurs have an offset B pivot (11spd derailleurs don't), which increases cassette size range, so I'd bet money that the 12spd derailleur can handle at least a 34 tooth, and maybe more. (Note: This will also depend somewhat on the chainring size differential, which affects the required derailleur capacity.)

[jkbrwn]

Yes - it can. Campagnolo say so. You just might need some extra links in ya chain.

Edit: or a different cage as per Basso69s advice

They state in their FAQs


I've got a 12-speed Super Record or Record rear derailleur. Can I use an 11-34 sprocket box?
Yes, but only if the internal rocker indicates 29-34.

[Basso69]

The original SR rear derailleur will not work, I tried. It requires a Chorus inner cage , part number RD-CH1203, can be purchased separately. Which converts it to the same as the latest SR 12 speed rear derailleur.

[fignon's barber]

I just received a new 12sp Record RD in the mail. It has 29-34 printed on the back side of the cage.

[Dave]

I just received a new 12sp Record RD in the mail. It has 29-34 printed on the back side of the cage.

That's as it should, be for any 2020 parts. FWIW, the medium 72.5mm cage will also clear a 36 tooth speocket, but doesn't have the wrap capacity for a 10-36 and 16 teeth at the crank. It was also necessary to add 1 inch of chain length.

[David Benson]

The original Super Record & Record 12 speed dearillers were not compatble with 11-34.
2020 models are. The part codes are RD19-SR124 & RD20-RE124