On Wednesday, I towed six 102cm x 204cm (4' x 8') sheets of 19mm (3/4") tongue-and-groove plywood flooring to my house. The carpenter helping me with my remodeling project estimated a weight of 160kg (about 350 lbs). The salesman at the lumber yard thought it was closer to 180 kg (about 400 lbs). High-speed cornering and rad manuevers were kept to a minimum.
Yesterday, I rode home from the office (about 25 km) with 4.9 meters (19.2 ft) of bike, trailer, and cargo (copper pipe, plumbing fittings, framebuilding supplies, CroMo tubing, and aluminum flat stock) averaging 25 kph with the help of a cooperative tailwind.
Haulin' can be fun.