I’m confused - or possibly you are confused ?
are you confusing shadow with rapid-rise (or something else) ?
the 772 shadow RD pull is 1.7 I believe - ? - same as other Shimano 9 speed
the bike pictured with the 772 RD is a 9 speed
I had issues trying to get it dialed in and changed out to an older model. I do see it says its compatible with all nine speed drives. Guess you can try it for yourself.