Originally Posted by Italuminium

Jan Jansen won the tour back in 1968, and when retired start rebranding Belgian frames (and later Japanese ones) under his own name. From the get go he equiped them mostly with Japanese parts, thinking that the stingy Dutch would love the good value of the Japanese components instead of the high zoot Italian parts. He surely was right about that!

This one looks like one of the early ones; quite old fashioned decals (even for the time) and early shimano 600 parts. I assume the parts are original; they look right for the period and are typical for JJ builds. The saddle is an obvious replacement, look for a nice Araya, Fujita or Kashimax replacement: don't bother with finding an exact match, most bikes I've seen of this type have quite horrible saddles with a quilted-look cover.

The components and frame style (my hunch is that it's one of the earlier Belgian ones) put in somewhere in the early seventies.

the headbadge is indeed the epitome of cool: sunglasses are kinda JJ's trademark. As of last year, he was still rocking them