Hopefully the ball part of the joint on your copy bike is the same size as the ball o the real Strida. I expect that it is, but it has to be a VERY tight push into the socket, else it would be popping out and killing people as their bike fell apart while riding.

I once saw a set of instructions where someone used a rope or something, wound it around the two parts of the joint with a piece of wood inside the loop and then twisted the wood around like a 'garrotte' and forced it in that way. I have the feeling that these notes were made by Mark Saunders.

http://www.strida.us/Tips-from-Mark.pdf

There are other methods here if you follow the links, but I haven'y checked them out.

http://www.stridaforum.com/forum/vie....php?f=2&t=379