I thought of a way to bodge a fix to use the braze-on K-Edge chain catcher with a braze-on front road mech
with a MTB left shifter. Oh god it's glorious
In the past, I know I got a R443/R773 front mech to shift with a MTB left triple shifter, the snag was the cable had to be quite loose when the chain was on the granny ring, but it did shift from granny to middle and from middle to outer and back again, no problems. In fact the R773 is probably the best front triple shifting mech I have ever used, especially from granny to middle, it's as solid as it gets.
Back then, I mistakenly thought the longer swingarm on those "R" front mechs meant they were supposed to be used on flat bar shifters, which I half-thought had unique 'flat bar' internals and I half-thought they just had MTB internals (they actually must have road internals, if they work with those "R" front mechs).
More recently, someone on here (freeflow) said the "R" stands for road and that's why the R443 front mech works with my 7703 left shifter, yes it does, perfectly.
viewtopic.php?f=5&t=127019&p=1306612#p1306382Again that brings me around to wondering why Shimano even makes 'flat bar" front mechs if they just have a road pull - it must be to keep the numbering in order and the groupsets in order, but we all know the R443 is a Tiagra and the R773 is an Ultegra. Why it's not a R673 I will never know, but anyway...
So wait, that means I can just put the braze-on FD-6503 back on again - with it's chain catcher - and use a MTB triple left shifter! I know I can because the R443/R773 front mechs (that work perfectly with a 7703 left shifter) both can be made to work on a MTB left triple shifter, as long as the cable is loose on the granny.
That's it, I can actually do it and have a chain catcher on. I don't care about a loose cable or half the shift not being there from granny to middle. I am lucky to have a bike that can accommodate either a bottom pull or top pull front mech.
Another good thing is the FD-6503 shifts better on my 48-36-22 than my FD-M771 does, which is pretty weird. I think it's probably because the M771 front mech is only meant for use up to 44t, while the Ultegra 6503 front mech is made for up to 53t and in the scheme of things, 48t fits a mech meant for 53t better than a 48t fits a mech meant for 44t.
So if anyone else is willing to use a braze-on road mech and have a loose cable on the granny ring, you can indeed fix this and use a chain catcher via the braze on route, even with a MTB left triple shifter. It's not pretty, but it's still a better option than having no chain catcher there at all.
Exhibit A: 12th Sep 2018
"It worked, but only if I had the cable deliberately too loose when on the granny ring, which I didn't care about because it did work."viewtopic.php?f=5&t=92886&p=1271771#p1271771Exhibit B: 9th Mar 2017
"The "Ultegra" R773 front mech (or the R443) can be used with a MTB left shifter, but it has to have the cable loose when on the granny (but who cares, it works)."viewtopic.php?f=5&t=112284&p=1107059#p1107059Exhibit C: 20th Apr 2016
"I used this setup myself with a XTR left shifter and a FD-R443 and FD-R773 and the only "problem" (not really) I had was you have to have cable slack at the end so, on the granny ring. Its a big push from granny to middle, but it still works and the shift from middle to outer to middle is just the same."viewtopic.php?f=5&t=105217&p=1004059#p1004059Exhibit D: 4th Nov 2015
"I never really could fathom whether it was a match with my MTB shifter but it did work quite well"viewtopic.php?f=5&t=101392&p=952214#p952214I have said the same thing every year, I'll make sure to say it at some point in 2019 as long as I am not banned for spamming.
We'll always be together, together on electric bikes.