So yeah, dumb question. What's the easiest way to find out the dimensions of stuff on my bike. Say the seatpost, for example?

Most of the stuff on my bike was given to me.

I've looked on the seatpost, but it's not on there... bleh.

A tape measure and an online conversion website (or a calculator or your own head).

K, I'm an idiot.. I guess I wasn't sure if there was a better way. thx.

nothing a caliper, a peice of string, meter stick, and a protractor can't do.

measure from the thickest parts of the tubes.

seatpost might be tricky. that's measured to tenths of a millimeter.

caliper or micrometer or dumptruck.

Vernier calipers are useful for measuring inside and outside diameters. They also work fairly well for figuring out chainline dimensions, measuring spindle lengths, and sizing loose bearings. You can get them for less than ten bucks at a building supply store. I prefer plastic versus metal because they're easier to read and they don't scratch the material. Just make sure it has metric measurements. The real trick is learning how to use it:

https://hyperphysics.phy-astr.gsu.edu...b/vernier.html

or

https://regentsprep.org/Regents/math/tools/vernier.htm

Probably way more information than you wanted...

No, that's perfect. Thanks!