Another thing to keep in mind is that size alone may not allow you to avoid the bike fee. Many airlines charge a fee for a bike no matter how small the box. It's the fact of the bike, and not the size of package, that triggers the fee. Now whoever checks you in may neglect to ask what's in the box, allowing you to get away with not paying the fee. But if they find out that it's a bike you will likely be charged. And in this day and age, I certainly wouldn't lie if asked.

I no longer fly domestically with a bike. For what many airlines charge, I can have my bike packed by a LBS, shipped and then reassembled and tuned at the destination. Even with a low-cost airline like Southwest ($75 for a bike), the extra $$ is worth not having to schlepp the bike around. Plus, since I ship the bike ahead of time, I can track its progress and take action if it doesn't arrive as scheduled. I have seen the disappointed look on someone's face when their bike didn't arrive with their flight and they are scheduled to start a supported event early the next morning.