Dan says:

These folks dragged their bikes from all over Europe and many overseas even. The detailing is pro level and goes well beyond just the frames – there were a lot of hand made pedals, shifters, rims, brakes. There was a week of chopper bike events with up to 30 mile (!) rides but there is not any hills there.

The gathering of choppers was hosted by the Chopperdome in Amsterdam. Their site has some more amazing photos. Via Star