Originally Posted by Canadian
I'm a female; I think my reach is too long on my Trek 1500. I'm struggling to figure out how to shorten the stem. I know it comes with Bontrager Select OS/7d and I've checked the website http://bontrager.com/model/04057/en
but now I'm confused. How do I know what size stem I'm using? I'm on a 54 cm.
There are four measurements for a stem: angle, length, steertube clamp size and handlebar clamp size.
Most steertubes these days are 1 1/8 inches. A few are 1 inch
Most handlebars these days are 31.8mm which is also known as OS (oversize). That's because the standard used to be 26.0, but from what I see, the OS is much more common now.
I "think" you're asking about length. Often it's marked on the stem and common lengths are 90, 100, 110, 120 mm. 80 and 130 are also fairly common. Those lengths are sometimes stated in cm instead of mm - therefore, 9, 10, 11, 12 cm.
If you're not sure about the length, you can easily measure it. The stem extends from the steer tube to the handlebars. Measure from the center of the steer tube (it has a cap which has a small bolt in the center - use that) to the center of the handlebar clamp. If you're using a US ruler, convert to cm by multiplying by 2.54 or to mm by multiplying by 25.4.