CRs:
Sorry for my previous message, which was incomplete. I hit the send button instead of the save button. To repeat:
Bob Hanson's drawing of stem extension measurement (http://i32.photobucket.com/albums/d7/k4drd/Bicycles/QuillStem.jpg)
shows a Nitto Technomics stem.
To add further confusion to this stem measurement discussion, I've found a sizing difference between various models of Nitto stems:
I've been using a Nitto Pearl13 stem for years. The Nitto Pearl is measured in the perpendicular dimension. This was shown in a small picture on the side of the blue box in which the stem was shipped. (I discarded the box long ago.) Hence, a Nitto Pearl 13, which is specified to measure 130mm at 90 degrees (perpendicular to the steering tube), therefore measures about 135 mm along the horizontal centerline. My actual, along the side centerline measurement was 137mm (another story, see below.)
I needed to reduce my reach by about 5mm, so I purchased both a Nitto Technomics (tall quill, approx 190mm) and also a Nitto Technomics SQ (short quill, 155mm). Both of these stems measure 130 mm along the side centerline of the horizontal part of the stem. These stems were in sealed bags without any documentation. These two Technomic (standard) stems are obviously about 5mm shorter than the Pearl 13, despite being the "same" size.
I've similarly found slight differences (about 3mm) in sizing for between the 3T Record 84 vs. 3T Status quill stems. I recall that the difference was about 3mm, with the Status being longer.
A Special Note: The Nitto Pearl 13 stem extension angle is approximately 72 degrees. Conesequently, the "horizontal" top part of the stem slopes down instead of being parallel to the top tube of my Richard Sachs bike, which has a 74 degree head angle. If I do some number crunching (high school trigonometry) I get 135mm along the free-space horizontal measurement, and about 137mm along the horizontal centerline of the stem.
Measure consistently!
Andrew Gillis
Pending Rain in Long Beach, CA