I want to run 7800 STI’s on a vagabond with an MTB chainset. If I just stick a 10s XT mech on there will it work? I know shimano have played around with cable pulls recently but going back to 2004-2007 era were they compatible?

Even then, MTB front mechs had more cable pull than road ones, so no, unless it’s a double.

Both are double (shifter and chainset)  but I guess that means the shifts will be indexed incorrectly. <span style=”font-size: 0.8rem;”> presume a road mech would work on an MTB chainset even if not optimally.</span>

I’d written off hylex + gevenalle as silly money for what’s supposed to be a budget build from the parts bin but its starting to look like a sensible option!

1x

I use an mtb triple, with 24/38 on the inner two positions on my gravel bike with a 105 front mech/11sp 105 shifters. Works ok, but I don’t think it would stretch to an mtb double easily.

1x

That was plan A, but would leave me with an annoying floppy STI unless I sold the 7800 stuff and bought campy/sram/microshift or went down the hylex/gevenalle route.

I use an mtb triple, with 24/38 on the inner two positions on my gravel bike with a 105 front mech/11sp 105 shifters. Works ok, but I don’t think it would stretch to an mtb double easily.

The double is 26/38 so that should be fine.

my opinion yes – run double 10speed 105 shifters (not sure of series but when they moved to both brake and gear as side exit) with a 26/38 XT crankset and an XT front mech (and rear) as far as I know same pull as DuraAce 7800 and it shifts very cleanly

edit prepared to be told otherwise but reckon matching the front mech to the chainset is a good starting place

1x…. That was plan A, but would leave me with an annoying floppy STI…

this is really not an issue, the lever isn’t floppy because there’s still a return spring holding it in the right place and it doesn’t affect the braking at all not having a gear cable in. I’ve had 105 levers on a 1×10 for a few years and it hasn’t bothered me one bit.

but would leave me with an annoying floppy STI unless I sold the 7800 stuff and bought campy/sram/microshift or went down the hylex/gevenalle route

Buy a brake lever and use it on the left. Or dea with the floppiness.

Didn’t front mech pull change on road 9->10s?

If its a double then it’s got a better chance of working, probably worth googling, info along the shimergo lines?

If its a double then it’s got a better chance of working, probably worth googling, info along the shimergo lines?

Shimano have a high bar to qualify as compatible. The distance between the chainrings changed (can’t remember if it’s 8-9spd or 9 to 10spd), but it’s not the crank it’s the small chainring has the teeth slightly narrower thus moving the center of the chainrings closer together. So it made no difference in the real world but shimano mark it as incompatible.

From the tech docs I could find, they seem to have messed around with front mechs at almost every iteration. Problem is knowing which of those actually had any impact in the real world.

my opinion yes – run double 10speed 105 shifters (not sure of series but when they moved to both brake and gear as side exit) with a 26/38 XT crankset and an XT front mech (and rear) as far as I know same pull as DuraAce 7800 and it shifts very cleanly

Presumably 9s mechs, 10s rear mechs definitely weren’t compatible. If that means 9s front mechs work though then it’s a good start.

edit prepared to be told otherwise but reckon matching the front mech to the chainset is a good starting place

Dunno, I think the chainring spacing has always been pretty consistent, just the rings got narrower.

this is really not an issue, the lever isn’t floppy because there’s still a return spring holding it in the right place and it doesn’t affect the braking at all not having a gear cable in. I’ve had 105 levers on a 1×10 for a few years and it hasn’t bothered me one bit.

After all this head scratching I might just go singlespeed!