Originally Posted by
DorkDisk
The M4120 long cage will wrap 42t. The shifters have to be compatible with the derailleur though.
Aye, that's the rub. According to Art's Cyclery (
Science Behind the Magic | Drivetrain Compatibility ? Art's SLO Cyclery), Shimano an 11-speed road rear shifter pulls 3.1mm per click. Shimano 10-speed pulls 2.3 mm. Shimano 10-speed mountain derailleurs want 3.4 mm. Tiagra 4700 works like Shimano 11 but for 10, so, for lack of better info, I'd assume it pulls 3.1.
By the way, riders have been mixing Shimano 10-speed road (2.3 mm) with 9-speed MTB (2.5 mm) with considerable success. Buena sera.