Originally Posted by
atombianchi
Howdy all,
I am looking to use my shimano dura ace 7700 GS (long cage) rear derailleur with a 9 speed mtn cassette with 34 tooth max cog. I would like to use this cassette for touring because of it's incredible low gearing. Is the 34 tooth to big for this derailleur? thanks for everyones help.
Most likely you won't be able to use the DA rear derailleur with a 34t cassette. It's possible but you won't know until you try. It's not so much a question of the capacity of the derailleur but the ability of of derailleur to be positioned so it doesn't interfere with the larger cogs and this is dependent on the bike's derailleur hanger location and exactly how it positions the derailleur.
Far too many variables not in your control. As Bacciagalupe posted above, you'd be far better off running a Shimano MTB derailleur, which will work perfectly with the shifters you have now.