Guy Vardi writes in:

The clock is build out of bicycle parts. One of the design principles was to use only used elements. Edison once said that to invent you need good imagination and a pile of junk. The designers took his advice seriously.

The Bike clock was build by Yedidya Vardi and Vladimir Zviagintsev of the Ron Vardi Center for the Development of the Gifted, in Rishon Lezion – Israel

And you can check out a video of the assembly, too!