Maybe one of the first pro raiders?
I don't know.

Thanks Johann. A friend has a complete, near NOS '85 Raider and he has just come up with the same measurements as me - 475mm (18 3/4). Not sure where the 18 1/4 measurement came from on the site? Perhaps the '86s were revised?

Thanks. Kurt.

18 1/4 was wrong.
Long time ago someone measured it wrong i supose.
A friend measured his pro raider ysyerday and top tube center to center is 47cm or 18 1/2".
Changed on the site