Originally Posted by
The Golden Boy
Funny, I have a 7803 FD and it's explicitly the WORST FD I've ever used.
Of course- the caveat is that I wasn't using it with a "modern" triple- so no ramps or pins. But those things are optimized for EXACTLY what they're designed for...
It's not the lack of pins that causes modern front derailers to struggle with vintage or aftermarket cranksets, but rather it is that these modern front derailers have inner-plate "step" features that are designed to work (only) with a specific tooth-count difference between the large and middle ring.
As for vintage front derailer's capacities, it seems that if the crank is a triple, then the capacity might actually be a little better in terms of vertical clearances, owing to the additional vertical (as well as horizontal) cage travel.
And whether or not one might use the small ring and small cogs at the same time might also impact the effective capacity.