[CleavesF]

Can you make a XTR/XT front triple work with Road STI shifters and a triple ultegra crank?

Or is it so bad in terms of mismatch it just isn't worth it? because of different pulls etc...?:idea:

 

[bopApocalypse]

Assuming that they're triple-compatible shifters, it should work - the cable pulls are the same.

However, the mtb der cage may be radiused to fit a smaller chainring (44?) than the road crank (52?). this won't prevent it from working, but may stop you from getting it set up perfectly - you'll have to put the front derailleur a little higher than usual.

 

[krisdrum]

Aren't most mtn fds top pull and most road fds bottom pull? It will likely work, but won't shifting be reversed on the sti lever?

 

[PeanutButterBreath]

Aren't most mtn fds top pull and most road fds bottom pull? It will likely work, but won't shifting be reversed on the sti lever?

There are top and bottom pull versions of certain MTB FDs, and some that can accommodate either cable approach. A top-pull specific FD will not reverse the shifting if pulled form the bottom though -- it won't work at all.

Since, as was mentioned, MTB FDs are shaped to accommodate a 46T at most, I really don't think it is worth it to try to make one work with a road triple.

 

[CleavesF]

Well can't you also argue most road FD were designed for 53T and 39T?

From my understanding MTB FD are supposed to work with the "trekking" cranks of 48T right?

Is 5 teeth really that big of a difference?

 

[PeanutButterBreath]

Well can't you also argue most road FD were designed for 53T and 39T?

From my understanding MTB FD are supposed to work with the "trekking" cranks of 48T right?

Is 5 teeth really that big of a difference?

Are you asking if the difference between the stock 52 on an Ultegra triple and a 53 is similar between the difference between a 48T and a 53T?

 

[dannybob]

The pull ratio is actually different. And the profile of the cage is different. Could someone make it push the chain around? Yes. Would you want to ride it? No.

From Shimano...

Can I use my road levers with a mountain bike front derailleur?
No. Due to the different actions within the shifters, these components do not work well together.

 

[danl1]

Shifter / FD will work fine. That's one thing Shimano got right. All (current) XT/XTR are dual pull, so that's not a worry, and pulls among Shimano triples are all the same.

FD/crank: Not so much. XTR's I know of only go to 44 teeth, some XT's go to 48. That's a fair bit away from 52. Yeah, you could probably hold it up high enough to get it to work-ish.

$40 (new) for a 105 FD would be a better call, IMO.

 

[MShaw]

It'll work, but its wonky. I do the XTR f. der. and Dura Ace STI thing every winter. It'll do the shift, but its 'rubby' in certain situations. IF yer lookin for perfect, don't do it.

M

 

[Al1943]

If you're talking about using mountain size chainrings there could be a problem getting the front derailleur low enough if it is a braze-on type or if you have a specially shaped seat tube.

Al

 

[CleavesF]

thanks guys! really helpful.