I flew back from Bordeaux with EasyJet about 10 days ago.
I used one of the CTC plastic bike bags and a lot of tape.
It was no particular problem and obviously the bike handling is down to the airport, not to EasyJet. I had no problems or damage - BUT
EasyJet is typically tucked away at the arse end of the airport (it was in Bordeaux) and you can guarantee that they will not have the scanner required for your bike.
In Bordeaux I had to check in with EasyJet, acquire my luggage tages, sprint across to the large items desk and check the bike in, then sprint back to EasyJet's terminal to clear their security before boarding.
Good news is that with the bike you get maximum luggage allowance which means I could check all my kit with the bike in a separate bag and then just take a tiny bag of hand luggage onto the flight.
Note that you cannot put anything else into the bike bag - just the bike.
This means that a second bag for your luggage is pretty much essential.