Barrettscv 

Can I run a vintage Suntour barcon shifters with a Shimano 9 speed cassette and A Shimano Deore SG rear derailleur? Will they shift a Campagnolo 9 speed cassette and medium cage RD?

-holiday76

sure. though no one could really answer how long your mech needs to be (short cage of long) without knowing what crankset and cog range you plan to run.

JohnDThompson 

In principle, yes; any friction lever will work. The one concern I see is that the barcon was designed in the days of 5 and 6 cog clusters and only has about 90° of travel; it may take some finesse to shift accurately over 9 cogs.

tmh657

I do it all the time. I keep a pair of Suntour Barcons on hand along with a modern 9 speed rear wheel and a Shimano 5700 RD. When I find a vintage bike I like and may be a keeper I attach the barcons, RD and rear wheel with 9 speed cassette to give it a thorough testing.

This Circuit had barcons and 8 speed as the Dura Ace RD was a generation that did not cover 9 speed.

Barrettscv 

Looks very nice, thanks

Sixty Fiver

It should not be a problem with a Shimano derailleur unless you are dealing with the newer mtb groups (XT Shadow) that have 1:1 actuation... I experienced an issue with Suntour barcons not being able to pull enough cable for a SRAM X5 because of the actuation ratio (1:1) did not allow quite enough travel to cover 8 speeds although it handles 7 just fine.

I just ordered a set of 8 speed Shimano bar end shifters and will switch my SRAM to a long cage Shimano rear d since I made some drive adjustments that don't need the extra wide capacity of the SRAM.