I just flew with my bike with KLM, I packed it in a cardboard box measuring 110 x 28 x 82 cm. I
sent them a facebook message 2 days before my flight reserving space for the bike. €55 is the price for short haul flights, I had to pay €100, the long haul bike transport fee, at the airport. They lost my bike in transit but delivered it to me 2 days later. Return flight was with Delta, no advance notice needed to be given, but they charge $150 and the TSA cuts open the box to test for explosive residue and does a shoddy job taping it back up.