These little bikes are beastial. When I was delivering food on a bicycle my rig was a 26" on super narrow and slick tires; bike was fast and I was also fitter than ever, could keep up pace with London's traffic no problem. One day I was riding, perhaps near 40km/h, when a guy passed me on a Brompton. He had a huge chainring at the front, which gave him an insane top speed.