Originally Posted by oneclick

There's a reason for that: they are junk. I know, I had two of them; soft alloy, no bushings on the pivots, all were loose to start with. I wrapped one around the spokes once and had to repair it (no money, that's why I had it to start with) - cage cut from aluminium plate, inner parallelogram arm from a section of angle. Was better than new, still junk.