That used to be the case, and I've often got my bike case on for free just by big-tipping the skycap up front and having him push it through without a charge, but I think the airlines are strapped right now and they are all under orders to charge for any large or overweight bag. In fact I just flew American and every checked bag is subject to a charge, so once they are looking at your bags and charging fees, it might be hard to avoid a bike charge.

However, it may be easier to coax them into charging just for a bag, instead of the bike fee, or whichever one is cheaper, especially if its light and compact. That's why I like the Sci-con case: its only about 8 lbs, so with a 15 lbs bike its under 25 lbs.