I’ve posted this a number of times that the Tiagra 4700 left double shifter seems to work with a Deore FD (Salsa Fargo Tiagra).

It kind of makes sense since newer road shifters work with GRX. And the direction is going towards 1x and 2x drivetrains only.

The only missing piece is how far back is it compatible. Can a early 90’s STI compatible XT FD work?

In my theoretical calculations, a Tiagra 4700 10 speed rear shifter should work with an older RD and an 8 speed cassette.

I’d like to try it one day. Running M900 FD & RD with a subcompact crank 2x8 might be a nice retro mod setup.

John