"Modular: constructed with standardized unit or dimensions allowed flexibility and variety in use; modular furniture: modular homes"
A few years ago, I built an adaptable tandem bike from two abandoned Malvern Star folding bikes. It was made with an "insert" between the halves of a folding bike. The bike was good, but I started thinking of the possibilities of something better or different. My modular bikes are the end result. The bikes are designed from the ground up to be assembled as tandems, recumbents &: load carrying bikes and the aim is to make these specialist bicycles affordable by using a cost-effective modular construction.
The design is patented and this article was featured in the Jan. 2005 issue of Velovision (you can find the patent here, search for 'modular bicycle' to find the patent documents. Pick the top entry you find).
This construction includes standard frame units with extras, like a suspended rear triangle, steering link, rack, trailer and recumbent seat & boom. The frame has attachment points at the ends for holding another frame or extras, a tube that acts as a static handlebar mount, and tubes that can support pulleys for a front-wheel drive mechanism. The seatpost doubles as a mount for the recumbent seat, as do the bottle mount bosses on the top tubes.
I have taken care to ensure that the extra features on the bike donít look scrappy when unused Ė for example a plastic plate can fit over the front attachment points. So far there have been 3 designs of the modular bike and I have designed a set of models of the bike which you can make for yourself at home.
The standard bike with front storage
A short wheelbase recumbent bike
A hybrid tandem bike with front steering
A hybrid tandem bike with rear steering
A back to back tandem recumbent bike
A long wheelbase recumbent bike
A load carrying bike
A paper model of the modular bike
As well as the bikes shown, you can build conventional tandems from the modular parts. Complete plans for these modular bikes are available online when you buy the book "An Illustrated Guide to The Cycle Zoo"