Hello,
Hoping for some guidance on what this measurement on my Anvil Journeyman jig is (I believe it is the 2.0)
It appears to be a headtube/axle to crown measurement and it goes to the bottom of the headtube fixture. The one data sheet I have doesn’t mention anything about this measurement. All I know is that the previous seller did say the measurement needs to be changed depending on a 1 or 1 1/8 head tube.
Any insight? Thank you
Hey, I haven’t looked closely at an Anvil fixture before, but from a first glance, I’d say that’s where you set the height of the bottom of your headtube (in relation to the center of the bottom bracket). I don’t think it would make sense to change the scale for a 1" headtube, because I assume the puck is located so the center of the bottom of the headtube is right at the pivot. You’d probably have to change the puck or adjust the position of the arm holding it if the puck is „stepped“ to work with both 1 1/8" and 1" headtubes. Maybe someone else who has that fixture can correct me if I’m mistaken. Hope that helped 
From what I was told by the original owner, the head tube height on the jig needs to change because the fixture uses cones and depending on the diameter of the head tube, it would sit higher/lower.
When I hold a tape measure up to the scale, the zero falls significantly farther down than the bb center.
Think of the vertical travel as setting stack in your design (but from the bottom of the HT). BikeCAD and RattleCAD output these measures based on the frame design for setting up fixtures.
Since the lower HT puck has been moved, I would guess it’s going to be a challenge to reset it relative to the BB along that scale.
I have a Journeyman 2 with cones for the headtube. The measurement is vertical from the bottom bracket center to headtube bottom. The scale is for 1-1/8" headtubes. Add 5mm for a 1" headtube.
This pdf may clear up a few questions.
Anvil_how-to-build.pdf (107.5 KB)
Exactly! That’s what I would have assumed.
I didn’t realize the fixture uses a bottom cone. After checking some more photos, it looks like the height of the arm with the bottom head tube cone isn’t adjustable. That makes me think the fixture is designed so that either the center of a 1" or 1 1/8" head tube sits right above the pivot point used to set the head tube angle.
That’s the first thing I’d try to confirm.
Edit: I missed that @rellis pointed out that the scale is for 1-1/8" headtubes
If the scale on the fixture is based on the bottom center of a 1 1/8" head tube, then when using a 1" head tube, you’d need to move the whole assembly down (i.e. subtract from the scale), since the smaller diameter tube sits higher on the cone.
If it’s the other way around — and the scale refers to a 1" head tube — then you’d need to move the assembly up (add to the scale) when using a 1 1/8" head tube.
Once you know which head tube size the scale is referencing, the next question is how much to adjust.
5mm sounds about right if the cone angle is 40°, which it looks like it might be. But this is just an approximation. The head tube that’s not centered at the pivot will be slightly off, since it’s not rotating around its own bottom center. That difference may be negligible depending on the head tube angle, but i think it’s still good to be aware of.
I made a quick sketch in Fusion, because I can’t do the math 
, to get an idea about how off it would be.
Here’s an example:
• Assume the center of a 1 1/8" head tube sits right at the pivot.
• You’re using a 1" head tube with a 69° head tube angle.
• The 1" head tube would then sit about 5.1 mm higher vertically and 2 mm closer horizontally to the bottom bracket.
• So, if you want to be precise, you’d subtract ~5 mm vertically and add ~2 mm horizontally when switching to a 1" head tube with a 69° head tube angle.
Please correct me if I’m wrong on any of that!
At the bottom of the head tube there should not be a cone, but a puck with a step in it, and then you have different pucks for different head tube diameters. The bottom of the head tube must always be exactly at the pivot point of the head tube angle adjustment thing. That must be true for every diameter and shape of head tube.
If that was not the case, the head tube angle and stack adjustment would not be independent of one another…
