Originally Posted by
ThermionicScott
That's one of those briefly-made Shimano FDs that moves diagonally -- seems like Shimano tried it with 105, RX100, possibly other levels for one generation before resorting back to normal geometry. I'd see if a normal FD gives you more clearance, Clarence.
(Pics courtesy of Velobase.)
PLUS
Originally Posted by
repechage
As you have seen, no diagonal movement mechanisms on this bike.
It was designed for tubulars too, in the 21 mm range.
DING DING DING.
It's actually not complicated, even if the post is wordy.
Looking around since, I've discovered that very few other derailleurs have this design feature - unsuitable for this bike, fine on many others.
So, I try another. Question was: which? Answer: probably lots of good options out there.
I'm more or less resigned to not fitting larger than a 23, but a 23mm will work (so despite others' posts above, I'm neither going to run 19's nor trade in the bike
). I will often try to fit roughly as large a tire as I'm comfortable with, clearance-wise, as I'm doing here. I think a lot of us here typically do exactly that. I'm also probably a lot bigger than anyone who's particularly comfortable on a 19mm tire.
That said: the Schwalbe's actual width is currently sitting at about 24mm, so I can probably squeeze a 25mm Master in (they measure small, so maybe .5mm of difference in width, and they might actually *less* tall...as per a measured comparison I just made with another set of wheel that sport the Masters). If not, no biggie.
I've already got a potential alternative RD possibly happening (ISO, FTW), so we'll see how it goes.
Thanks, all, for the many constructive responses.