Contact the airline you're planning to fly overseas with and ask about its bicycle policies. Not all airlines will take bikes as baggage, but many will. Since the bike counts as one piece of your checked baggage, the airline will take it for free. Ask what the packing requirements are as well.
Pack the bike according to the airline's requirements. This generally means taking the air out of the tires, turning the handlebars until they're parallel with the frame, and sometimes removing the pedals. Some will allow the bike to fly in a bag, but many will demand a box, which they may sell. Ask at bike shops otherwise. Bike shops can also provide plastic spacers to fit between your forks, helping them avoid damage during loading.
Pad the bike in the box as much as you can with soft items; this will help protect it during the journey.
Pack a small pump and the necessary wrenches so that you can reassemble the bike at the other end.
Arrive at the airport at least an hour earlier than you would without a bike. You will have to go through the oversized luggage line, which may involve extra inspections that take extra time.
Collect your bike at baggage claim after the flight and reassemble it. If you put it back together at the airport, you will even save yourself a cab ride into town.
Disassemble your bike as much as you can and pack it into a box. Add plenty of padding; shipping by post is even harder on a bicycle than traveling by airline. It will likely be thrown around and dropped along the way.
Weigh the box and measure its length and girth (the length of a string wrapped around it). Shipping rates are calculated from these measurements.
Determine which shipping service to use. Private couriers are more expensive than the U.S. Postal Service but will take larger parcels. If your bike and box together are less than 70 pounds, and its length plus girth is less than 130 inches, it can go by USPS. Be aware, though, that length-plus-girth measurements of between 108 and 130 inches nearly triple rates from those for items 108 and less. UPS, FedEx, and DHL can all take up to 150 pounds and 165 inches length plus girth.
Get quotes from several different shipping companies and choose the lowest.
Bring the packed bike to a drop-off location or arrange for a pickup. Both the USPS and private couriers will do this.
Buy insurance for your package. This will pay you back if it is lost or badly damaged en route. Insurance is offered when you pay for shipment.
Contact whomever is receiving the shipment and give them the tracking number provided to you; they will then be able to know when the bike is arriving.
