I gave this frame to a good friend, and he’s made single speed conversion
It was built in the Jordaan district by RIH in the early 80’s, using the famous Reynolds 531 tubing.
I took the frameset in to the shop with my friend, and was told by the then current owner, the master frame builder Menheer Wim Van der Kaaji, (still building at 76), that his father or would have made it.
The RIH Sport brand was limited to building 250 frames a year, as the original RIH Bustraan was sold, and RIH Sport had a license for road racing and track frames.
The Jordaans RIH’s have a serial no. one the headtube, and RIH Bustraan has the serial no. on the bb, and were factory produced in greater numbers, albeit still on a bench with 531 tubing in some cases.
You can see the headtube serial here
Sadly Menheer Van der Kaaji shut the RIH shop soon after our visit , with no heir to take over the business, an end to one of Hollands finest hand made brands and an era in cycling history, so I’ll stick my neck out, and say I think these frames will appreciate well in value in the future.