The two-form bike is a convertible bicycle that can be configured in an upright or recumbent position. It takes just a minute to change from one design to the other.
Recumbent bicycles are faster and more comfortable for many riders than ordinary, upright bicycles. However, traditional recumbent bicycles have several features that, for some riders, make them less attractive than an upright model. The two-from bike is a convertible bicycle that can be upright or recumbent: it takes just a minute to change from one to the other – offering riders the advantages of both designs in one frame.
The custom framing of our bikes includes forks and other angled components, allowing quick and easy transition between configurations. The two-form bike is patented in multiple countries, including the United States and China. Our prototype model can be seen in the image above.
Recumbent bicycles have several advantages over ordinary, upright bicycles. Due to their reduced air resistance, recumbent bicycles are faster than upright models. Second, a recumbent riding position is much more comfortable than an upright one.
Of course, upright bikes are still overwhelmingly more popular, and for good reasons. In city traffic, the higher riding profile of the upright configuration makes the rider more visible. Upright bicycles are also less sensitive to uneven terrain, such as curbs. Additionally, sometimes riders prefer the “look” of a classic, upright bicycle.
Most recumbent bike riders would prefer a bicycle that could be reconfigured to an upright position when needed. Also, riders who may have been interested in recumbent bikes, when faced with a choice between models, usually prefer to invest in an upright bike. But given the added choice, many of these same riders would purchase a bike that offers the best of both models in one vehicle.
Last but not least, the two-form bike looks like a chopper!
The frame of a two-form bike consists of three main sections:
1. a polygon-shaped assemblage, with a down tube, seat tube, top tube, two head tubes, and two additional tubes, rotating synchronously in the head tubes,
2. a fork, stuck in either of the head tubes, depending on the desired configuration,
3. stays, mounted to the main, polygon assemblage at different angles, depending on the configuration.
To convert the bicycle into its recumbent configuration, one simply needs to:
1. rotate the main polygon upwards,
2. remove the fork from the upper head tube and insert into the lower head tube,
3. change the angle of the stays in the main polygon assemblage, then
4. mount the backrest to the stays.
The idea may be implemented in various ways. Examples are presented in Fig. 2 above and Fig. 3 below.
Unlike in the initial prototype, there is no Cardan joint in the second design. The tubes that rotate in the head tubes are connected by a cable, which requires no removal during transformation from the recumbent to the upright position. Our design can easily be the basis for the mass production.
At this point, we have the international patent PCT/IB2019/051265 and national patents, including in the USA, China, India, Brazil