Originally Posted by
JanMM
To measure bike things accurately, you'll need vernier calipers, which measure inside or outside diameters. Really cheap plastic ones are available and suitable.
Yeah, but you don't need fancy equipment to measure for a stem. The choices are 1" or 1 1/8". That's within the "eyeball" range.
In a pinch you can clamp an adjustible wrench loosely around the stem shank and measure the distance between the jaws.