The exact documents that you have to provide depend on where you are shipping to and from and the purpose of your shipment. 

Bikeflights will ask you for the following documentation: 

• Confirmation of shipper and recipient information, including in-country phone numbers
• Repair or Return Authorization form that describes your shipment's contents, the repair that will be completed (if applicable) and the value of the item(s) being returned. 

When you ship a bike or gear for return, repair or warranty service, your shipment will be classified as a “Commercial” shipment. The clearance fees will be calculated while placing your order on our website. Even if the item you are returning is broken, you must declare a shipment value greater than $0. 

Customs reserves the right to charge duties and taxes on any changes that occur to goods that are being repaired, replaced or returned. You may use the value of the repair for repair shipments or the "at cost" value for replacement or return shipments in place of market value.