Shimano 105 FD Trim
 

I'm having problems dialing in the FD trim function on my 105 equipped Domane ALR 5.

When the cable is looser with some slack, it will trim the big chainring, but not the small.

When I tighten the cable with the barrel adjuster and take out the slack, it will trim the small ring but not the big.

What do I need to do to get the trim to work on both chainrings?

Are your limit screws too tight, limiting your ability to trim?

Here are the dealer instructions for the Shimano FD-5700 front derailleur. If you follow all the steps completely, you should have a properly adjusted derailleur.

Shimano FD-5700 Instructions

I don't suppose you've taken apart the front chain rings to clean them? Asking because I did this and didn't put them together facing the right direction... if you have the Pin on the large chain ring goes under the crank and the number indicating the number of teeth on the other chain rings faces in towards the frame of the bike...

My FD shifted MUCH better once I got the chain rings on correctly!

105 front derailleurs set up procedures are going to differ depending on the year model. 5700 and earlier are pretty simple. I'm assuming since you have a Domane ALR 5, your 105 derailleur is going to be a later model 5800 or 5801. These 2 have a much different setup and adjustment process, as well as a different trim function as well. I've made videos on both types that may be helpful to you. The most common issues I see with incorrect setup is not enough cable tension and not installing the back up plate and utilizing the stabilizer screw.

Thanks to everyone for the advice.

The limit screws are fine as it shifts back and forth very well and doesn't drop the chain.

I've not taken anything apart, still exactly like I got it from the lbs.

I think I'm just going to have to get it up on a stand and turn the barrel adjuster a quarter turn at a time until I reach the elusive "correct" cable tension.