A beer or two

 

Perhaps 10?
In the vid he shows using frame backbone as est Horz.
Here is the deal, you can use the front wheel to est vertical,
and make the rear match, (the EZ way ) as you just can't change the front there is no adjustment for it.
To look at the backbone as a reference is good for posterity but truthfully it is a useless commodity.
There is no way to align the vertical with the front wheel and the make it 90 deg to the backbone too.
Pick one.
i gaurntee one or the other will be out of sync.

 

Why wouldn't the rails under the seat be perpendicular to the neck if the frame is straight.

I use bike jack just to stand bike up and level, wheels still on the ground,
make sure the axle is parallel to the swingarm pivot shaft with your homemade tool(it's in the FSM),
level frame in seat area, make rear rotor vertical 90 degrees using top link, trace the laser line on floor off rear rotor, move laser and protractor to front rotor, set front rotor 90 degrees by turning handle bars,
laser line off front should be parallel to rear line, won't be on top of each other, with offset rear wheel, if not parallel, adjust front lower link, recheck from step one after any adjustment, all 3 front mount bolts need to be loose when adjusting.
I find if you have to put much tension on the top link to get rear vertical, the belt side donut mount is usually out of shape.

I'll keep this method, bikes go no hands straight down the road.

 

Because you CANT adjust front wheel.
The rear is the only adjustment I know of.
The frame could look like a figure eight but as long as both wheels are vertical that's what counts.
The rear wheel is the only one that will lean right or left to match the front.
So really the wheel alignment is an orchestra of a couple things
The rear wheel has to match the vertical of front-
Rear wheel in line with the front.
Pretty simple and you are allowed to do as you wish.
I hope we are having a discussion here and not who is the biggest Toad in the room.

 

When the neck is vertical, and the front rotor is at 90 degrees, it's straight ahead, this method is adjusting the whole rubber mounted drivetrain to that.
No contest here, just stating what works for me.

 

After re-reading your last post, I think We're saying the same thing, correct, you can't adjust the front,
if the end results are the neck is vertical, front rotor 90 degrees, rear rotor 90 degrees at the same time, it's straight, whatever method used to get there,
but how you gonna keep the front at 90 while trying to adjust stuff, the slightest nudge throws it off.

No worries King, no butthurt here

edit, forgot to mention, get the rear axle parallel to swingarm pivot shaft, is actually the first step, important

 

Good to know we are all just having a discussion.

I am going to post a pic of a tool I made for 10 bucks later today to center rear wheel to swing arm
-It is better than the HD POS wire and rubber grommet they use. (and dead on accurate)
Anything I am saying here is as over a beer-not to be taken in any other manner.
Probably because of typed conversation some finer things are lost or added.
Most of us that have messed around with either hot rods, helicopters, boats, planes and ships -building them that is
compound angles.
This becomes simple.
To the novice that reads these forums -they get a little reticent.
Lets us focus on simple-for everyone and anyone can do this

*One, Your Bushings, Front mount , hemi joints HAVE to be in EXCELLENT shape, or you are wasting your time.*

So I will attempt to sum this up and everyone else can do it their way ( I look fwd to it)
As for me -
.IDC what the backbone reads as i can't fix it or adjust it.
Center rear wheel with a tool. (wheel to swing arm)
*Get the front wheel vertical locked and stationary.
Make the rear wheel match and behind the front with string, laser straight, edge whatever
.Get the rear wheel vertical with engine top mount.
We have to match the front as there is no adjustment on the front.

So to me measuring the Horizontal of the frame at this point is just for drill. if I now level it and the front is now not vertical which will I choose to work with?
I will ignore the frame, and check the front, make the rear match
I find I will screw with all three measurements at the ame time as one will effect the other.
Once everything starts to get close I stat clamping thins dwn, top mount first
As a final check, I put the lasers on the disk and set up a back board about 12 feet away to shoot at.
The front laser and rear laser should hit the same spot-albeit one will be below the other as I can't shoot through the front laser
When you are all done and square you can measure the frame across the top if you want.
If the wheels are vertical and aligned, there is not a dam thing we can do about factroy jigging.

 

What throws me off there is, how do you account for the offset, front and rear rotors are usually not on the same plane, if they end up that way, wouldn't the bike be crabbing down the road?
That's why using lines on the floor makes offset irrelevant, just looking for parallel to each other, while the front, rear rotors and neck vertical.
Seems if you get the lasers off the rotors to hit the same spot on the wall, the rails won't be horizontal.

In a frame jig, the neck rake and vertical is set with frame C/L, everything else is built off of that,
using the seat rails for horizontal is ez access spot, but also assuming the neck is vertical,
I don't know how to verify that easily, but if bike wasn't wrecked, it should be straight up.

None of this stuff is 100% accurate,
but the bike goes straight, not twitchy in the turns, and tire wear is symmetrical, that and some cold beer is all I need.

 

I should put a pencil to this and do some geometry, but I'm too lazy and don't want to think that hard. Still, I think there's a hole in your procedure there.

It's not enough to verify the front wheel is vertical. It has to be both vertical and pointed straight ahead relative to the center line of the frame. Call that "dead zero steering angle".

The only way to get a vertical front wheel at dead zero steering angle is if the frame is level. Say the frame is canted over a few degrees to the left. If you turn the steering head to the left, there will be a point at which the front wheel shows vertical, but the steering angle will not be at dead zero.

In that way, I don't see how you can do this without setting the frame to level first. (And yes, measuring off the top of the frame under the seat makes the assumption that it is square to the steering head at that location.)

 

Appreciate your thoughts.
Here is the problem with HD.
I have not ever found a frame that will measure HORZ level, and yet get the front wheel "0" vertical.
It becomes one or the other.
SO what to do?
*Put it on the waffle table and bend the neck to match the frame ?
That would be the correct fix.
Your thoughts.?
It seems a compromise is in order and call one of the numbers good, and which one?

*If I ever strip my frame dwn I will do this, cause mine is off a couple degrees.