What is the minimum insertion length for a quill stem? I have one without any clear marking.

What is the maximum insertion length? Is there a way to determine this? A way to estimate it? I want to get a longer stem so I risk overinsertion into the butted part of the headset.

What is the minimum insertion length for a quill stem? I have one without any clear marking.

What is the maximum insertion length? Is there a way to determine this? A way to estimate it? I want to get a longer stem so I risk overinsertion into the butted part of the headset.

Usually it's about two inches minimum. The quill on a quill stem goes inside the steerer tube of the fork; I'm not quite sure what you're referring to as the butted part of the headset.

On a Nitto Technomic quill stem, the minimum insertion line is 160mm from the top, and the overall length is 225mm, so the minimum insertion line is 65mm, or 2.56", from the bottom of the quill.