Can't Setup Front Derailleur to Change Up and Down

[Eugbug]

I can adjust it so that I can change from the middle ring to the small ring or middle ring to the large ring, but not so that I can change between all three. The high and low limit screws are not restricting movement of the deraileur. This only seems to be a problem since I replaced the middle ring with an oval one.
If I squeezed the rails of the derailleur closer together would it help. Seems like there's too much backlash in the system and the cable just can't produce enough displacement to shift both up and down. Another possibility is the little bumps on the inner face of the big ring that catch the chain are worn down too much, so unless the derailleur rail pushes really tight, it won't shift the chain.

[CharleyFarley]

(05-24-2019, 02:33 PM)Eugbug Wrote:  I can adjust it so that I can change from the middle ring to the small ring or middle ring to the large ring, but not so that I can change between all three. The high and low limit screws are not restricting movement of the deraileur. This only seems to be a problem since I replaced the middle ring with an oval one.
If I squeezed the rails of the derailleur closer together would it help. Seems like there's too much backlash in the system and the cable just can't produce enough displacement to shift both up and down. Another possibility is the little bumps on the inner face of the big ring that catch the chain are worn down too much, so unless the derailleur rail pushes really tight, it won't shift the chain.

As you found out, the problem arose after installing the oval ring. Is it thicker, or does it have spacers making the trio wider? I wouldn't squeeze the sides of the derailleur closer together because you'll likely end up with the chain rubbing all the time. Do you still have the old chain ring? Put them back together and measure the overall width. But first, measure the overall width with the oval ring in place. If the oval ring is making the whole assembly wider, then it's the cause of the problem. It may be possible it will work with a different derailleur. I have a Schwinn hybrid with a triple chain ring, and I found the derailleur adjustment is really finicky, barely able to cover all three chain rings.