Originally Posted by
maartendc
So that means the Tiagra 4700 shifters and derailleurs have 11-speed type cable pull, and the 10 speed Tiagra cassette has the same sprocket spacing as an 11-speed cassette?
No. The 4700 Tiagra cassette is the same as previous Shimano 10-speed cassettes. The 4700 Tiagra rear derailleur is basically the same as Shimano 11-speed rear derailleurs. The 4700 shifter has cable pull unique to 4700 (and apparently GRX400), in order to make the combination of 10-speed cassette and "11-speed rear derailleur" work.
You could stick a 10-speed 5700-series cassette into a 4700 drivetrain, and it would work fine. You could also stick an 11-speed R7000-series rear derailleur into a 4700 drivetrain, and it would work fine. (You could stick a 4700-series rear derailleur into an 11-speed R9100 Dura-Ace drivetrain, and it would work fine. But people would give you funny looks.)