Bicycles are normally made out of round tubing, but there’s really no reason that square tubing couldn’t be used, as seen on this bike made by Aaron Seiter and based on Michale Ubbesen Jakobson’s “BauBike” design. As Seiter puts it, after seeing Jakobson’s bicycle, he “fell in love…The design is so clean, simple, and honest.”
Somewhere in the back of my mind, I keep thinking that there’s a structural reason that round tubing is preferable, but it’s been “several” years since I went to engineering school. Tubing shape aside, Finding the weak points on this unique and very square frame would be an interesting statics problem. According to Seiter, however, he has “put the bicycle through the ringer (off curbs and over speed bumps) and so far she has held up very well.”
It’s definitely a very interesting and visually striking design. The chain is quite long and the powertrain is a “fixie” design, where the rear wheel will not move without the pedals turning. This configuration can substitute for a rear brake, which is good since this bike does not have traditional brakes, and Seiter doesn’t plan on adding them any time soon.
Here’s a video of this bike being ridden quite successfully, and even without hands at one point. Very cool, and very unique as Seiter desired.