If you have a wider rear tire or offset you will have to measure differently.
Hopefully get the same number going past the front wheel as there will be a space between the rear tire and front when the line is pulled.
Now I have heard HD has had the rear wheel from the factory off-center on purpose, Width problems and trying to make the final drive in line. (Sprocket to sprocket )
You are on your own with that one.

 

I suppose the thing to do is level the bike (backbone), then test the angle on the steering neck. In theory, exactly perpendicular. In reality?? Who knows, but my sense is if it's off by something more than some inconsequential fraction of a degree, you'd already know.

What you need to know us what angle to measure at the backbone that will give that particular frame a true vertical at the steering head. Hopefully the answer is zero degrees on the backbone. Otherwise, the frame isn't square.

Maybe I'll do that on my ElectraGlide the next time I have the batwing off. Should only need to do it once. Doubt the frame is going to bend over time.

My personal view is to start with leveling the frame at the backbone, then finish the procedure from there. The proof will be in the pudding. If you do all that and the bike doesn't track straight, you either screwed up the procedure or your frame is tweaked.

 

I have not ever found one frame to measure "0" horz, and yet have the front wheel measure "0" vertical.
They are close but not perfect. (couple degrees at the wheel)
That is why I skip the frame rail measurement as I just can't fix it.( I do measure it just for reference.)
I don't want the rear tire running vertically with the frame, and the front tire doing something else.
That is my theory as to how i do it, for now, and I am all ears about how others deal with this.

 

That's where I think you have a hole in your procedure.

What is the point of measuring the front wheel for vertical unless you have a reason to think the steering head is vertical first?

Granted, there is the possibility that measuring the backbone for level won't establish a true vertical steering head, but what else are you going to do? Unless you have established the steering head as vertical, measuring the wheel for vertical is really just an indirect way of measuring the steering angle.

 

The two wheels, front, and rear , in purrfect alignment.
If we are to skew that just to get the frame to say Zero from the uncentered rake....
I know what you are saying about diminish angles "do I actually have to forks centered."
The rear wheel exactly lined up with the front is as purrfect as it gets.
Is it not?
If we are to "Jack" that measurement or compromise it, we will forever run with the front wheel forever slightly into a turn.

 

I guess I don't get it... Most Harleys do Not track the rear tire exactly in the front tire Track!!! And No... they don't turn... they track down the road with No Hands...

 

You lost me there. That doesn't make sense to me.

I'll go back to this: The first step in your procedure is measuring the front wheel for vertical.

Why? What is it you think you are measuring when you do that first?

I don't think that measurement tells you anything unless you either (a) verify the steering head is at true vertical or (b) verify that the steering angle itself is at true zero first. Otherwise, the vertical angle of the front wheel means nothing.

The GlidePro/Schex method solves that by leveling the frame first. That acts as a surrogate for (a), and is built on the assumption that the frame is square. I'm not sure how you would go about measuring (b) independent of anything else.

Even if you don't think the frames are made square, you still have to start somewhere. You have to come up with something that puts the steering head vertical before the measurement of the front wheel for vertical means anything.

 

I am confused I guess?
If we square up the rear in all respects the finaly look at the vertical of the front wheel and it is off,
what do we do?
Ignore it?
or compromise?
Maybe I just do not understand the question.

 

Square up the rear relative to what?

Say you put an angle gauge on your rear wheel, and it measures dead nuts on the money vertical.

What have you learned?

I say you haven't learned anything unless you also know whether or not your frame (and therefore your steering head) are also vertical.

In other words, when you say "square up the rear in all respects", if that means you've squared it up to the frame and both the wheel and the frame are true vertical (relative to Earth, that is), then you've gotten to the same point as the GlidePro/Schex method. On the other hand, if "square up the rear in all respects" does not include somehow measuring the frame for level, you aren't squaring the rear wheel up at all, and any subsequent measurements of the front wheel don't tell you anything.

 

If the rear wheel is sq to the frame and swing arm ,
I guarantee you the front wheel will be leaning slightly left or right.