I'm going to take my bike with me on a plane. Do I really need a special bike travel bag to have it transported safely? I have a road bike that I want to bring with me to the place I will be flying to.

I know that there are bags that are designed especially for this kind of situation: the bike travel bags such as the one shown on the picture below.  But, as they are expensive (that one costs £250 for example) I would like to evaluate all the alternatives (if any) before I go ahead and spend so much money with something that I would use once in a blue moon. How could I prepare my bike to be taken on a flight if I don't own a bike travel bag?
I recently flew to Europe with my wife, and we brought along our bicycles. Our solution was to disassemble them the night before and place them into cheap Nashbar bicycle bags. We wrapped pipe insulation foam around just about everything to avoid damage from handling. For extra protection, we then stuffed these into the standard bike boxes provided (at a minimal cost) by the airline. I would highly recommend the internal bags, as the TSA opened both our boxes during each flight, and did not bother to close the boxes back up. Wheels or other components could have easily fallen out in flight had we not used canvas bags inside the larger boxes.

Also, be very careful about which airline you choose to fly on. Most airlines have a surcharge for checking bicycles, and this can vary wildly between carriers. Our tickets were initially on Delta, who wanted to charge us $200 per bicycle per leg. With a 2-leg trip to Amsterdam and back, this would have cost $1,600 to ferry our bikes, which was ridiculous. Thankfully, we discovered this within the 24-hour cancellation window and switched to Continental, who only charged $100 per bicycle per itinerary, costing us only $400.

At the end of the day, though, transporting your bike via airlines is expensive and annoying. Our next touring bikes will absolutely have S&amp;S couplers to allow us to fit the bikes in regulation-size checked luggage, which should help us avoid airline surcharges and additional TSA inspections.

Good luck!