Trying to run drop-bars and road bike shifters on an MTB can be tricky because road bike front derailleurs are all bottom pull, ie, not compatible with most MTBs.

The CX70 Shimano front derailleur has a top-pull option and works a treat. It comes in many guises and is especially built for Cyclo cross applications.

It comes in 34.9 and 31.8 clamp bands, plus braze-on. The 31.8 comes with a slightly ugly shim to take it down to 28.6.

I used it on my small Karate Monkey with 22/34 chain rings  (and Durace 9 speed shifters) and it works brilliantly,  so I would expect it to work even better with more appropriate sized rings, by that I mean typical 2 x 10 touring setups or Cyclo-cross sized front chain ring combos.