The 1993 rigid frames with the Pepperoni fork used 1 1/4" threaded steerer tubes. The cup OD is 37 mm, the crown race ID is 33 mm, and the stem quill OD is 28.6 mm. In 1992 the M700 also had the all-aluminum Pepperoni fork so I'm pretty sure it was 1 1/4". The 1992 M500 had a steel Tange...