The triple trees i'm using allow for a 1 1/2inch OD fork tube which
kinda limits me to the material i need to use. Mild steel piping dosn't
come with a OD of 38mm (1 1/2") and machining down the next size
up mild steel pipe would leave me with no side wall so my next best thing
is to use chromoly tubing. Unfortunately i'm not qualified to weld chromoly
so i am in the process of mocking up a front end out of exhaust tube then
i'll send that away to get replicated out of Chromoly. I'm sure if i look
hard enough there is also the option for using steam pipe or similar but
at least with 4130 chromoly tubing its extremely strong and has a memory
( which means when it flexs it flexs back to its original state)
I cut the insides out of a old wooden pellet to support the front wheel
in place while i work around it. It's at this point here when i do my trail
measurements so that i can sit the wheel in the correct place. For me i'm
setting it up with a trail measurement of 1 1/2 - 2".
At the moment what i've done is bent up some 3/4 pipe so that it goes
from one end of the axle and bends around the back of the tyre then meets
up with the other side of the axle. This will be the rocker that pivots
up and down when the wheel goes over a bump. Some people use just a piece
of plate either side of the axle as thier rocker which is also fine and
probably easier to adjust trail settings but for me i'm using the rocker
style that joins both rockers together so that they can be garunteed to
move as one.
I've made up a bracket that i've TIG welded in place to the base of the
fork. For now i've made it out of 3mm plate but the final bracket will end
up being thicker. This bracket is welded to the fork and then eventually
bolted to the rocker so that it becomes the pivot point for the front end.
I have taken a rear shockie off one of the farm bikes i have lying around
so that i can mock up top and bottom shockie mounts. The idea is if you
draw a line down the length of the shockie then back along the rocker to
the pivot point then back up to the top shockie mount you should have a
triangle shape. If you do then the shockie will work more efficently and
handle better.
Now that i have the general concept mocked up i got a few things machined
up so i can start putting it all together. Pictured here is a new longer
axle plus a couple of extra bushes made up for the ends of the rocker for
the new axle to go through.