Titanium Bolt Sizing
When measuring a titanium bolt, it’s best to use calipers and a thread checker. You can probably work it out with a metric ruler though.
For example, if you were looking at an M8-1.25 x 50mm titanium bolt:
The titanium bolt size is M8. You determine this by measuring the diameter of the shaft in mm to come up with the "M8" value. The socket wrench the titanium bolt uses does not determine the titanium bolt size. This is a common mistake.
The titanium bolt length is measured from the end of the threads to the bottom of the titanium bolt head. That's the length of the shaft, excluding the head. In the example it is 50mm long.
The titanium bolt thread pitch is the distance between threads measured in millimeters along the length of the titanium bolt. Determining the thread pitch can be difficult without a thread checker tool.
Titanium bolts on this sight use the standard thread pitch per size. I’m sure there are some odd balls out there but generally speaking, bicycles and bicycle parts use titanium bolts with these thread pitches.
M5=0.8 thread pitch
M6=1.0 thread pitch
M7=1.0 thread pitch
M8=1.25 thread pitch