I keep reading threads on here about folk who are moaning about rubbish chain line but have a geared set up. I’m sorry but I just don’t understand 7 to 10 gears on the back, 1, 2 or 3 on the front. If your frame is straight and you are using the middle position at the front for a 1x set up how can it be rubbish?

My only conclusion is people have bent frames, derailleur or hangers. Or simply have no idea what they are talking about.

Please explain.

Anything outside of a dead straight line isn’t ideal for a chain, and the further you stray from it, the worse it gets. Recent chainlines moved out even further, probably to cope with ever widening tyres,giving a pretty awful line to the bigger sprockets. Try a brand new 3×10 on the stand in that gear and the noise from the chain is pretty horrible as it leaves the ring, it sounds like the mech rubbing even when there’s loads of clearance.