Just thought it might be worth putting a brief note here on my recent experience flying EasyJet from Bordeaux to Gatwick.
I used the £12 plastic CTC bike bag, turned the bars sideways and rotated them down as far as possible, removed the pedals and refitted them on the inside of the cranks, put the chain on the smallest ring up front, largest cog at the back. Strap the crank to the seat-tube so that the extended chainside crank helps protect the chainring.
I wrote twice to EasyJet, once asking for written confirmation that the bike bag would be OK. Second time to confirm my baggage allowance.
With a bike booking you get an automatic holdbag allocation as well.
Despite all of their (EasyJet's) assurances, the baggage handlers at the airport asked for the tyres to be deflated. I had already done this and they checked. I've heard of tyres being "deflated" with a Stanley knife", so decided to play it safe!
The check-in process via EasyJety is a PITA. You need to arrive with your packed bike. Queue for check-in and get your boarding pass, go to the baggage handling area, get the bike weighed and the tag fitted. Then (at Bordeaux) you had to go to the oversize luggage handling facility - which is in a separate terminal. Then return to EasyJet's terminal for security clearance, before finally boarding the plane.
Even allowing 2 hours, we had no spare time at all!
At the plane, the bikes went on last, at Gatwick, they came off last, but were delivered via the carousel!!!
No damage. Worth it for the low cost, but worth getting the paperwork printed and carrying it with you.