I definitely prefer taking my folding bike than my Specialized. I would NEVER take my bike on United. They lost my bike luggage and their attitude was like "so the F what? It's not our problem". I nearly lost it. It took them two days to get it to me, then they lied over and over again on the day they were supposed to return the luggage, claiming it had been delivered when in fact, it hadn't. If I hadn't been on them, calling them and calling corporate all damn day until the luggage arrived with my doorman, I don't think I would have ever gotten it back. I only fly American. I won't even fly the United affiliates if they told me it was free! Beware of United. There's a reason why they're bankrupt. I will be laughing my ass off the day the creditors do repossess the 14 planes they tried to take on the runway a couple of weeks back. Ha!
Anyway, I took my Specialized on the plane. Do make sure you know what the dimensions are. It's LINEAR inches too, so you just need to make sure they're aware of the fact that it's linear inches. Otherwise, if they go by LxWxH, you will definitely get charged. I went to American with my bike the day before I was supposed to leave, got a tape measurer and had them measure out the dimensions. They also printed out the applicable regulations for the dimensions from the AA computers and gave me the printout. I was speaking to the supervisor, so I had her write her name out on the printout. Then when I travelled, I just presented the printout, which helped because a lot of the people never dealt with someone travelling with bike luggage. They were inclined to charge, but when I produced the printout and the name and number of the supervisor, they were able to confirm I was within the guidelines, so I didn't get charged.
I never have a problem with my folding bike. Never.
Koffee