Freight bicycles, carrier cycles, freight tricycles, cargo tricycle, or bakfietsen, are human powered vehicles designed and constructed specifically for transporting large loads. Vehicle designs include a cargo area consisting of a steel tube carrier, an open or enclosed box, a flat platform, or a wire basket. These are usually mounted over one or both wheels, low behind the front wheel, or between parallel wheels at either the front or rear of the vehicle. The frame and drivetrain must be constructed to handle loads several times that of an ordinary bicycle. Other specific design considerations include operator visibility and load suspension. Many, but not all, cycles used for the purpose of vending goods are cargo bicycles.