I've acquired a Raleigh Suntour (circa 1990s) frame which I am re-fitting. I need to refit the headset and so I need to know the dimensions of the steerer column. The frame had a threaded stem.
I've measured the external diameter as about 22-23mm (so about 85-86% of an inch). I measured it by applying measuring calipers to the outside of the steerer column i.e not the cups for the ball bearings.
I've looked at various websites (such as Parktool) about standard threaded headset sizes and they say they range from one inch to one and a quarter. So even the smallest standard is quite a bit larger than my measurement.
I've checked my measurement several times and I'm sure it is about right. Do I have a steerer with an obsolete measurement or have I made some silly mistake.
Thanks in advance