MTB Top pull front derailleur with road groupset

[GrasB]

I've got a bit of a problem with a CX framed bike that has top-tube cable routing. The front indexing is unreliable to say the least, the shifters & front mech' work flawlessly on a bike with down-tube routed cables but as soon as you take the cable round the return pulley on the CX frame things start getting unreliable. My thought is to use a Deora XT 10spd top pull front mech in place of the 105 mech removing the problem. My main concern is that as MTBs use wider chainlines than road bikes & a little worried that the front mech won't go down to the bottom chainring. Also the rider wants to use a 50 or 52t top chainring & nominally nothing supports anything higher than 48t, but as I know people regularly exceed the top tooth capacity of road mechs I'm not overly concerned with this. Finally are the pull ratios different on road & MTB front mechs? I'd appreciate any insight.

 

[Zoiders]

The pull ratios are indeed different so plus the capacity is wrong as well just like you said.

However - all is not lost as Shimano have released a new cyclo-cross groupset that works as a top pull.

 

[GrasB]

Had seen the Shimano CX lines announced but the front mechs are double not triple.