-
I’ve run 48s TA rings with 7800 no problem, wasn’t sure if 44 would be too decreased a circumference. That’s the issue right? The arc of the derailleur matching the arc of the rings?
I’ve used 7800 shifters to pull a XT front derailleur and seem to remember it was the small middle that was giving me issues due to cable pull matching the gaps. I could fudge chai line to a degree with a different BB I figure?
Eeyorecore-
That’s the issue right? The arc of the derailleur matching the arc of the rings?
That's what will make your shifts less pleasant and more prone to failure even if you fix the chainline
I could fudge chai line to a degree with a different BB I figure?
Good luck with that. The FC-M737 is supposed to use a 107mm BB, and if you want to bring the outer ring in to a road chainline you need to move it 8mm, i.e. you're looking for a 91mm BB 😮
The alternative would be to find a 34T×58mm PCD ring, which is just as improbable as a 91mm BB but at least it's technically feasible as a special order item from somebody like Gebhardt.
gbj_tester
Define "comfortably". The smallest outer ring in the 7800 series was 50T, that's a 12mm bigger radius than a 44T.
It would probably work if the chainline was right, but it wouldn't be pretty and there's a higher than normal chance of throwing or jamming the chain.
The chainline is is a separate issue. In theory, the M737 middle ring is at 47.5mm, but the 7800 outer is at 47.5mm. If you wanted to get the chainline on an MTB crank to replicate that of a road crank, you'd actually use the inner and middle positions, not the middle and outer. An FD-7800 is probably never going to reach the stock outer ring on an FC-M737, and if it does it will be so far into the arc of travel that it's going downwards rather than sideways when you initiate a downshift.