Trying to tune up the mechanical FD (Shimano 2203 triple) on my old road bike. I followed the park tool guide and I seem to be stuck.

The problem is that I can't find a setting that would result in correct shifting from the middle ring into the big ring. Depending on the position of the high limit screw, I see two outcomes: either the chain does not get off the middle ring at all, or, if I turn the screw even a little bit, the chain goes right over the big ring and falls off the outside. There is no middle ground. I get the feeling that the derailleur cage is too wide to shift correctly. Chain tension does not seem to matter and vertical position of the FD is set correctly.

I suspect that my problems are caused by mismatched components. The bike originally had this 2203 triple FD, a 8-speed chain and a 8-speed crankset. I had most of the drivetrain upgraded to 10 speed piece by piece. It used to work more or less correctly, though shifting into the big ring was always less than 100% reliable. Right now I'm trying to put the original 8-speed crankset back on and that's where things are going sideways. Visually, it looks like the 8-speed crankset (Bontrager) has slightly narrower spacings between chainrings than the previous "upgraded" one (105). I guess that could explain the troubles (this crank and this FD used to work properly with a wider, 8-speed chain, but not with the narrower 10-speed chain.) But I can't find any confirmation online that different road triple cranksets can have different spacings.

Is there anything I might be missing? If nothing else works, I'm thinking to get a new 10-speed specific FD, but I'd rather not spend any money.

If the FD height is correct (3mm or less clearance between the outer plate and the big ring teeth at their closest approach), and the outer limit is adjusted to barely clear the chain when it's on the big ring/smallest rear cog, then the shift always works, and the chain isn't thrown off. Have you verified that the outer plate is parallel to the big ring when viewed from above? And are the rings facing the correct direction (the teeth are offset slightly).

I only have 8-speeds on all our bikes, but I believe that's the correct procedure regardless of speeds. Matching the components to the speed count is important in the front, since the spacing between the FD plates is critical with the skinnier chains.

Do you have some odd ball combination of ring sizes?

What was original and replacement tooth combos?

What if you back off the H screw AND cable tension slightly?

I see nothing from the OP on the tooth count of these various changes , you just use the out of the box

cranksets as is? like I know all that .

They are both 52-42-30 cranksets. The only difference is that the original has 8-speed rings and the upgraded crankset has 9-speed rings.

If you upgraded to 10 speed, including the chain, you might be having an issue because the 8-speed chainrings are designed for a wider chain than you're using. It may not be a spacing issue as much as chainring thickness. That's a total guess, though.

I tried to make a picture of the FD. It's hard to get the camera in there and to get everything in focus, this is the best I could do:



What you can (hopefully) see here is that the chain is on the middle ring, the shifter is in the highest gear. With limit screw / tension as shown, chain rubs against the inner wall of the cage, but does not yet shift up. At the same time, there's already a sizable gap between the outer wall of the cage and the outer ring. If the cage is moved any further to force shifting, the chain will go over the ring and fall off.