Flying with a bike box I've only advised BA twice, the first time the response was along the lines of "why are you wasting your time telling us", the second time (booked via Amex)
they were asking ridiculous questions, including the size of the batteries, er, it's a road bike, the power source is me.

The other 20-30 times I've not bothered, I always arrive early for check-in, perhaps that helps.