depends on how much weight you want to haul around. I did 137# on the burley flatbed but thats pushing it. I wanted a traielr that could really haul loads. i was going to get one from bikes at work but they were 6 weeks out. so I built three of them. the green one is for 300# loads so I can haul about anything. the yellow is for work to haul lumber and such about 200# I towed a 200# box 10 miles with it.
I jsut finished a thrird that I forgot to take a picture of. I made the yellow one from my burley flatbed ad it cost less then buying the parts to do so from someone. but then I wanted a light trailer for small stuff so I made a ligth one that was simple to build and uses the same wheels as the yellow one.