I tried adjusting the front derailleur on a 3x10 trekking bike. After fiddling around a long time, I concluded that is probably not possible to make all cogs work with all chainrings. How do I know what gear combination should work? Should you for example be able to use the fifth gear with all three chain rings without chain rasp? Should you also be able to switch between all chainrings in the fifth gear?
Currently, the three largest cogs are only working with the smallest chainring. If I adjust the front derailleur to allow shifting on the second chainring, I lose the ability to downshift from the third to the second chainring in higher gears (the chain rattles but does not come down).
I also experienced something similar when I crosschain on a 3x8 city bike. I have never had any issues with a 3x7.