bikebreak

I'm running compact with 11-30 in back, chain is just only enough to clear 50x30, and just short enough to run 34x12. normal cage SRAM force rear mech

The rear mech is at a pretty severe angle in 50x30 and 50x27, I am thinking of swapping to a medium cage. Also have a road link I could use to get clearance, but don't think that would help mech angle.
I have a longer chain sitting around, but don't know if it's long enough to work with medium cage. I don't want to go to trouble swapping mechs and chains then finding out I need a longer chain

thanks

noodle soup

The derailleur is irrelevant to determining chain length. Skip the video to the 4 minute mark.

woodcraft

If you are saying that the chain is stretched almost straight when in the big/big,

that is not a problem- leave it. Might need to add a link for roadlink; medium cage would not affect chain length.

I use a roadlink w/ Sram red & up to 11/34 cassette (10 speed). It works well, but the chain is slack in small/small, which I don't use anyway,

so if you you use the roadlink & short cage, it's important to get the shortest chain length anyway.

I got a Force medium cage RD, but the red/Roadlink set up is lighter, so I kept that.