Most manufactures measure their stems from the steerer insert/quill center to the HB clamp center. Not along the top of the extension, quill draw bolt center to bar clamp center. The difference is about 4mm. Enough to confuse what you're actually trying to get/sell.
This is assuming an approximately 72*-74* angle between the steerer quill and the horizontal extension.
> Richard,
>
> Here is a pretty simple and clear illustration
> (link originally submitted on RoadBikeReviews.com forums):
>
> http://i32.photobucket.com/
>
> BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA
>
> _______________________________________________
Andrew R Stewart
Rochester, NY