Bicycle Mechanics - How Are Stems Measured???

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tpelle
07-22-08, 08:49 AM
I'm thinking about replacing the stem that came stock on my Trek 820 with one that's a little longer in order to improve comfort with my new trekking bars. I know I'll need a mountain-bike specific stem due to bar diameter, but I don't really know how long my present stem is, or what size to buy, because I don't know how they are conventionally measured.

How are stems measured - center of steering tube to center of bars?

HillRider
07-22-08, 08:52 AM
How are stems measured - center of steering tube to center of bars?
Yes, that's exactly how they are measured. The measurement is taken along the stem so, for a up-angled stem, the actual horizontal distance will be smaller depending on the angle.
tpelle
07-22-08, 09:29 AM
OK, thanks. That's kind of what I figured.

JiveTurkey
07-22-08, 02:41 PM
If you don't want to do the trigonometry yourself, this chart is really helpful: http://www.habcycles.com/fitting.html It gives you relative rise and reach of stems based on their angles and lengths.