Virgin allowed us to take our 23kg hold bag and then an additional 30kg for the bike for free last year.
BA were also cheap, £40 / each way for the bike IIRC.
Most airlines will take the bike, but it will come out of your usual baggage allowance – it depends how long you are going for, and how much stuff you need? We were going for 6 months so it was a full bag + bike each!
A lot of planes will be shared by a couple of airlines (code sharing I think its called?) so worth checking, as the baggage allowance / fees is based on the airline stated on your ticket. On our BA flight they guy in front of us in the queue at checking got stung for 100s for additional baggage, but he was on a different ticket. We turned up with 60kg each and paid £40 each!
Avoid Malaysia air, we booked with them as they were cheapest for flights+bike at the time, but between booking and arriving at the airport they changed their baggage allowance, stung us for an additional £600! And their customer service is simply terrible.