SB7121 is a frame that posed a lot of questions. Firstly what was it, a Road or Time Trial frame? I finally measured it and it has the angles and proportions of a Time Trial frame. It also had a seat pin that would suit Metric tubing, so after taking the paint off and revealing bare metal tubes, I measured and discovered that this frame was built with Reynolds 753T. It has the classic over size seat stay caps, Prugnat head lugs and Cinelli BB shell.