Wait you saying this will work with my 5700 shifters? If so massive thanks, because I have a spare 34 cassette in the shed!Duck! wrote: ↑Mon Feb 24, 2020 1:37 pmIf you can find a 4600-series Tiagra derailleur, that will take up to 32T, and works on the same pull ratio as your current stuff. 4700 & GRX is derived from 11-sp. and is incompatible. For fitting bigger sprockets you need to look at so-called "9-sp." derailleurs, which work on the correct pull ratio. R3000 Sora will take 34T, while "Shadow" type MTB models will fit 36T comfortably.
https://www.pushys.com.au/shimano-sora- ... lleur.html