"Frontier Airlines announced bicycles fly free for passengers paying “Classic” and “Classic Plus” fares. Passengers paying
the lowest “Economy” fares pay the standard baggage fee of $20 for a bicycle. This policy takes effect for tickets purchased on or after today, Wednesday, April 13, 2011. Bikes are now treated as any other standard luggage on the Denver-based airline.
According to Frontier Airlines, “Classic” fare is just $25 more than Economy. The increased Classic fare includes two free checked bags, while Economy passengers must pay $20 for each checked bag. Frontier also waives the oversize fee for bikes. If your packaged bike weighs more than 50 lbs Frontier will assess their overweight charge. Most U.S. airlines charge fees ranging from $50 to $200 for travelers flying domestically with bicycles."