The SBDU seemed to stop using their H reference towards the end of 1979, meaning the frames coming out of Ilkeston at the beginning of the 80s would only have the SB frame number stamp and nothing to identify a frame as somehow different. I guess from this point on, the only reference to a specific build or geometry would be shown on the paperwork and build sheets that followed the frame and fork through its production, eventually ending up in Ilkeston’s records. If your frame does have an H reference then you still really have no idea what the ‘H’ was all about unless you have original documentation; that is why I try and measure, document and figure out all my frames.
After working out that SB664 was built from an early type of Imperial Reynolds 753 tubing, I wanted to use the calipers and metal rule again to try and figure out what type of use the frame was built for. Was the geometry designed specifically for Road or Time Trial; the outward appearance such as the frame transfers suggest that it is probably an SBDU Time Trial frame. SB664 is an early SB numbered 753 frame and was probably ordered in first part 1976 or even in late 1975. Reynolds 753 was brand new, it had only just been shown to the public in trade shows and it wasn’t widely available outside of the TI-Raleigh team. So what was this frame designed to be?