Rake and trail, Am I correct with these calcs?

[notlob]

I'm building a 1982 CB900 with zx9r RWU forks using zx6r triple clamps and a 2007 cbr600rr prolink swingarm. Now before I weld the rear shock mount I've been checking the front end and difference ride height makes.
I've been told 2nd or 3rd hand that the optimum angle of the swingarm is 12.5 to 13.5 degree's. To achieve that I end up with the following rake and trail 23 deg rake and 93mm trail with no weight on the suspension the wheel just resting on the floor. see center in photo below.

My question is, Is the rake and trail acceptable and how much will it change with the weight of bike and rider on the springs?

Photo removed to avoid further embarassment.

 

[rockcitycafe]

93 is probably safe, the image is too small to read your calcs though, so I can't verify that... the rake angle will change under braking, you're correct on that, for full weight transfer, you want to calculate the rake at full rear suspension extension, and full front compression, beyond that and you're in a stoppie and trail doesn't matter anymore ;D... good on you for doing the math too, god forbid anyone should build a rideable cafe racer

 

[mydlyfkryzis]

Something I am not sure of in your drawings. Is the circle the wheel axle? If so, why is its height changing? the axle will always be at the same height.

Also, the blue line is the Neck line, the red the fork tube line?

Just wanted to be sure as the dimension you show seem to be off. The axle height will not change with loading (other then a small amount from the tire flattening). Of course, under hard braking the angle of the fork neck will become steeper, shortening trail, as your diagram suggests, but I don't think the way you measured it, with the varying height of the axle, is right.

 

[notlob]

mydlyfkryzis, Thanks for pointing out the obvious error, must of been one of my blonde moments.
The center drawing is the bike supports on jacks with no weight of the bike on the wheel. I can let let rest on the suspension as I cant connect the rear linkage to the frame until I'm happy I will get the trail in the right ball park.
The fork offset is 30mm and the steerer stem and forklegs are parallel.
Yes blue is neck line and red is fork.

At a rake of 23 deg I get 93mm Trail
At a rake of 25 deg I get a 106mm Trail

I suppose the question I should of asked was, When the weight of the bike and rider is on the suspension the rake will narrow correct? therefore it will shorten the trail, I dont want it to shorten enough to make it unstable. So what is the likely degree of change in the rake when bike is resting on its springs?

 

[rockcitycafe]

It will decrease the rake angle, what you need to do is compress the front forks and extend the rear shocks and re measure the angle, simulating trail at full braking weight transfer

 

[notlob]

OK Think I got the hang of this.
I dropped the clamps down the forks 120mm full travel and lifted the back end so that it was just resting on the floor. So that should imitate maximum braking. So I end up with the following

At rest with rider on bike
Rake 24 Deg Trail 100mm

At Maximum braking
Rake 20 Deg Trail 75mm

Is there anything alarming or concerning about those figures?