Originally Posted by
DGULL
I've been looking at Tiagra 4700 10 speed STI shifters with a Shimano XT M785 10 speed dbl chainset (24.38t) and 10 speed MTB cassette (11-36t).
Older 9-speed MTB derailleurs can be shifted as 10-speed using older Shimano 10-speed STI shifters. Something like Ultegra 6700 with a 9-speed Deore or Deore XT rear-derailluer. Front derailleur is a bigger issue.
Stay far away from Tiagra 4700 if you want good cross-compatibility.
Tiagra 4700 is an odd-duck, it's 10-speed but uses 11-speed cable pull ratios.