Originally Posted by KCT1986

Based on the info you provided, 3x front, this is probably 10 speed rear group, either 560? or 5703 version. 5703 had the shift cable running alongside the Hbar, 560? is as shown below.

. . . .

Regardless, road 10 speed and lower used shorter cable pull for the FD. This meant that more force was needed to move the FD.

Not sure if there is any change to the FD that can really make shifting lighter, (assuming that the current FD is working properly). Not sure if any compatible FD would be much of a change from the 105.

If it is not a cable/housing issue, there is not much you can do. Check that the inner cable is not damaged and possible use a lower friction cable. The other item to verify is that the housing is in good shape and routed optimally.