Do you have any tips for installing oval chainrings and fine tuning the front derailleur for their use?
Before beginning, it is important to not that front derailleurs will never shift as perfectly with oval chainrings as with circle chainrings, so it is important to tamper your expectations.
A Chain Catcher is Recommended
Nearly every oval chainring front derailleur set-up can benefit from a shim placed between the frame braze-on and front derailleur, but the chain catcher is still highly recommended. The shim angles the rear of the derailleur down and moves it back to help clear the taller rings while putting the cage in a better position to push the cage down to the small chain ring. Both SRAM and rotor make these types of shims.
Place Derailleur As Close As Possible to Tallest Tooth on Outer Chainring
Start by shifting the derailleur into the small chainring and then loosen the cable anchor bolt. Put the derailleur into a position that places the outer plate on the derailleur as close to the tallest tooth on the ring as possible without touching, while making sure the outer cage is parallel to the big chain ring. Torque the derailleur fixing bolt.
Set your lower limit screws so when the derailleur is shifted into the large cog, the inside of the derailleur cage is as close as possible to the chain without it touching, then pull the cable tight and tighten it. Shift the rear derailleur into the middle of the cassette and then shift the front derailleur into the big ring.
If there is a struggle with this shift, you need more cable tension. Use your barrel adjuster. Shift the derailleur into the smallest cog to check to see if the chain is rubbing on the cage of the derailleur. If it is, back out the outer limit screw.
