It is a good feeling when the drawing match's up with what is in the garage.
The tires on the trike are old and weather worn at best, so I will need a new front tire and should get it mounted and on the rim before I get set on tube length or set on rocker arm length.
I have not completed the 18" rim drawing yet, but started it.
I can not find it now, but I read a chart (a guideline of rakes and wheel placement ) and it was for chopper's, so keep thinking " Chopperhandbook " but have not found it, anyways there was the 3 1/2" off set pivot to axle point with a 1 1/2" trail, like in my drawing, but I do believe it was for a 45 degree rake, and the next rake in the chart was 50 degrees. It was a guide to find the rocker arm length and pivot points with a specified rake. Once one has the pivot point location on the fork tube one can determine the tube length needed. Created by years of experience and data, at least that is what my mind remembers.
I will have to check again for it, but I remember the 3 1/2 to 1 1/2 configuration because that is how I got the idea of the 5" rocker arm length. Each rake angle gave a different configuration of figures for the wheel placement.
Now if we have to allow for expansion and compression of the shock/springs with the movement of the rocker arm, it is said that one should allow 32.5 degrees exp. and 32.5 for comp. for a total of 65 degree rocker arm swing area.
With that said, full expansion leads to a zero trail point and full compression would create a 3" trail, estimates made off the drawing, and I found a weight felt on the front end to rake ratio that was for choppers, not the same as a trike, but a estimate of 35% of the over all trike weight should be on my front end. Figure this out in lbs. and one gets a idea of what strength material is needed to be used so the new front end meets the need of the trike and one gets adequate braking power on the front wheel. I do like the bullet design to finish of the end of the fork tubes, and I seen them on Sugar Bears site if I remember correctly. A project for sure, even if you have someone else make them for you, but nothing good ever came easy.