Apparently it varies by the airline, as well as the fare one pays. Possibly even the season, or special discounts.

Bike Travel | Bicycling

So, rates could vary from FREE to $20 to $50 to $200.

Can you get your bike compacted down to 62 inches? Perhaps splitting it to two bags?

An option suggested in some of the articles is DO NOT SUPPORT AIRLINES THAT CHARGE EXORBITANT BIKE HANDLING FEES. Some smaller airports may have a limited selection of airlines. But, for larger more common routes, choose bike friendly airlines.