Drop down bars

[Nigelnaturist]

Is there not an issue with the front mech on MTB having a different pull to road bikes so you would have to replace the front mech as well to get it to work with STI shifters?.
I would like to do this mod to my subway if i had the time and cash .

Dérailleur's are pretty dumb, I think a bigger issue is MTB and road chainrings and sizes, or more to the point the curvature of the cage, i.e. a MTB FD is unlikely to match road chain rings and vice-versa, though I did get a Sora 3300 FD to work with a touring chainset of 26/38/38 in 2012, but it wasn't perfect. The only other thing would be the distance between chain rings if this is different then the pull as you say may well be different.
I know using slightly different cabling routes effect the pull slightly.

 

[cyberknight]

Dérailleur's are pretty dumb, I think a bigger issue is MTB and road chainrings and sizes, or more to the point the curvature of the cage, i.e. a MTB FD is unlikely to match road chain rings and vice-versa, though I did get a Sora 3300 FD to work with a touring chainset of 26/38/38 in 2012, but it wasn't perfect. The only other thing would be the distance between chain rings if this is different then the pull as you say may well be different.
I know using slightly different cabling routes effect the pull slightly.

Thought so
Sheldon brown concurs
Indexing Road/MTB
The ratio of cable movement to derailer movement differs with Shimano's "road" vs. "MTB" front derailers. This can cause indexing problems if you use a "road" front derailer with upright handlebars or a "MTB" front derailer with drop handlebars.

 

[Nigelnaturist]

@cyberknight you forgot the next bit
"It is not a problem if you are using a friction system, such as bar-end shifters or downtube shifters."
which leads me to believe its the distance between the chain rings thats the issue rather than the FD itself, for instance if a road shifter moves 6mm to shift the chain and the MTB shifter 4mm ( i don't know the actual distances), the MTB shifter would move the cage enough to shift on to or off the ring.
So the actual issue is in the shifter opposed to the FD, i think it gets more complex with tube angles ect..

Edit I might be completely wrong however as I am not well this week.

 

[cyberknight]

@cyberknight you forgot the next bit
"It is not a problem if you are using a friction system, such as bar-end shifters or downtube shifters."
which leads me to believe its the distance between the chain rings thats the issue rather than the FD itself, for instance if a road shifter moves 6mm to shift the chain and the MTB shifter 4mm ( i don't know the actual distances), the MTB shifter would move the cage enough to shift on to or off the ring.
So the actual issue is in the shifter opposed to the FD, i think it gets more complex with tube angles ect..

Edit I might be completely wrong however as I am not well this week.

Indeed, i was just trying to say its an issue rather than getting all technical.

 

[Nigelnaturist]

sorry the codeine/morphine is doing my head in this week