I just wrote a big long thing and bikeforums ate it... but the gist was that 3T seems to measure by reach (flipped up) rather than extension like other stems. Angle decreases reach relative to extension so a 73 degree stem is going to have much more extension for the same "length" reach.

they may measure the (virtual) length of it using trig, ignoring the actual stem angle.

My 3T stem is 84 degrees so just about 2 mm longer than what it should be depending on how you measure. I asked for a ruler at the store when I went to buy it - I think the salesperson thought I was crazy.

These are the same "size"

http://www.photoscene.com/kimandsteve/images/4587.jpg

Giant TCR C2 Medium - 90mm Ritchey (survey bike)
Specialized Langster 56 - 100mm FSA
Redline Conquest 54 - 110mm Ritchey
Vintage Trek 1400 56 - 120mm no-name quill

When I bought the Giant 2+ yrs ago, I had it fit with a 120. I've gradually work my way down (...110, 100...). Think I've finally got it dialed in. Just went from 105 to 100 on the Langster. I have a nice Easton 100 I might try on the Redline for CX season. I'm in the process of installing a threadless fork on the Trek, just so I can tinker with the stem fit.

In the words of Pcad, "what's wrong with me?" ;-)

I have two 3T ARX Pro stems, 100 & 110. The 100 is dead on (C-C), the 110 is closer to 115.

OCR2 with a 120mm. but it's interesting to me that the poll has more at 100-110. When I swapped out the OEM stem for this one, I just got whatever the LBS told me to get. I've had some fit issues for the years, now I'll have to re-visit this to see if they really got it right.

the distribution always falls in a bell curve, i cant believe statistics paid off!!!

I just ordered a 100 for my orbea opal, I had a 120 on there but i felt stretched on it for a while so I skipped the 110 and went down 2 sizes hopefully its a better fit...