front derailleur adjustment with new chain

I installed a 10-speed chain yesterday to (I thought) finally get me on the road on my 105 Schwinn upgrade. The rear shifts like a dream but now I cannot get the front the shift properly. When going from small to large chainrings the chain hesitates then jumps right over the ring and lands between the ring and the guard. If I adjust the limit sufficiently to prevent this it won't go up to the large ring at all. I considered that the chainrings were too wide but the chain lands on the small ring perfectly every time.

I kept the original Suntour FD in place because it is low-normal which I thought would help ease my transition to STI. I have an FSA FD that I can install but it will require a clamp and an additional cable stop.

I'm wondering now if the cage is just too wide for the chain. Before installing the new chain and 10-speed cassette I had the shifters hooked up with the existing front and the old 8-speed cassette and chain and the front worked fine. Otherwise, what kind of adjustments can I make to the derailler? The rear of the cage is pretty much neutral...I haven't messed much with toeing it in or out.

Advice is appreciated. I'd like to actually be able to ride this thing someday!

 

Who knows for sure? SunTour stopped making derailleurs long before 10-speed chains were invented, we don't know what you're using for shifters, and we don't know what you're using for a crank set and rings. That's a lot of unknown for a definitive answer.

But before whipping out your credit card, try this. Verify that the bottom edge of the outer plate of the front derailleur clears the teeth of the big chain ring by no more than 1-2mm, and that the outer plate is parallel with the chain rings (or very slightly toed out it the back). Verify that the outer plate barely clears the chain in its outermost position (big-small) when against the high limit screw. Verify that the inner plate barely clears the chain in its innermost position (small-big) when against the low limit screw.

After limit screws, front derailleur height and alignment is the main cause of over/under-shifting.

If this doesn't work, write back with the remaining details of your setup so we can make more suggestions.

 

I'm running 105 (5600) shifters with KMC X10.93 chain and the original Sugino crank and 52/40 chainrings. The rear is all recent Shimano (Sora RD with 12-25 5600 cassette). Jagwire cables and housings.

After tinkering some more I discovered that it would shift to the large quite easily while still in the lowest gears (i.e. more angle entering the cage) so I toed the rear out a touch and squeezed the cage closed a small amount. Problem seems to be solved. However the ease of setup and great performance out of the modern components in the rear suggests strongly that replacing the FD would be a good idea.

Rick

 

Very resourceful. When you're mixing components that were never meant to work together, you have to be. And a new FD would be my first choice for improvement, too.