Lighter bag less protection.
When I’m close I put rotors and pedals in the other hold bag. can get you close to 1kg for something Enduro.
Also your allowance is 23.9kg on the way out but only about 23.5 on the way back as they weigh in Lb. You could also take the seat post out for a bit of saving too..
I’ve never been pulled up that badly on the bike bag though BA couldn’t even weigh it at LHR as it was too tall for their bag drop., The old balance it with a foot works too, along with being really nice, asking how the check in person is doing and looking a little flustered, if you have some spare weight n the other bag it looks better too 😉