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Stem Measurement(3 posts)

Stem MeasurementJuniorRacerFL
Jun 28, 2002 5:42 PM
Hello, im thinking about getting a new stem but i dont know what size i would need because i dont know what size i have now on my 54cm trek5200. Is there any certain type of measurement or is it just from the furthest end of on one part of the stem to the other? I come up with 130mm and that seems a whole lot bigger than it should.thanks
Center of steerer tube to center of the bar (nm)Dave Hickey
Jun 28, 2002 5:52 PM
sort of...C-40
Jun 29, 2002 8:10 AM
There is more than one place to measure center to center.

With threadless stems that may have several available extension angles, most brands have switched to measurements taken along the side of the stem, parallel to the extension angle, from the center of the bars to the center of the steering tube.

Older quill stems could be measured by laying a scale on the top of the stem and measuring from the center of the quill to the center of the bars, since they virtually all had the same 73 degree angle.

If you lay a scale along the top of most new threadless stems, you will find that a 110mm stem may measure 115mm. If the stem has an angle that is much more than 80 degrees, you also have to consider the affect of the angle on the horizontal reach. A 110mm, 90 degree stem, for example, will only have a horizontal reach of about 105mm.