[python] Re: Round and square tube & the jetrike.

  • From: Henry Thomas <whpthomas@xxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Tue, 16 Jan 2007 19:09:59 +1000

25hz wrote:
Now, I'll just clamp the python front end to the frame jig, and make the
backbone meet it at what ever angle seems convenient - likely around the 65
degree range (it has rod end pivots so angle adjustment is simple).  I'll
bring down the ground clearance to 3", so CoG is now at 15".  I plan to run
the seat at 30º so that's another 1.5" CoG drop.  Due to the frame design of
the tadpole, I can lower the seat height by another 1" by adjusting the seat
mount method, so that leaves the CoG at about 11.5".  By adjusting the
swingarms up 10 degrees it gets me a little over 2" lift at the swingarm
pivot so the CoG is marginally lower than the pivot at this point and that
isn't adding suspension sag.  I can minimize that by tightening the adjuster
ring on the shock though.  If it all goes pear shaped on me, I can still
reset everything back to the Jetrike defaults though as there are multiple
holes in the tie rod brackets.  As I get a little time to finalize the
designs in 3DS, I'll post them for critique.  :)  I did manage to get the
three pivot tubes made along with 6 Delrin bushings and machined some
threaded adapters to weld into the end of 1.25" x .049" box tube that will
take a 1/2" bolt.  I also have some made up for 1" x .063" box so I might
try that first for the other arms of the rocker and if they fail, I just
make a new one with 1.25" arms instead.
Just thought I would let you know, that adding +/- 10 degrees to the swing arms has very little impact on the seat height and self-centering effect in the simulation. Angles approaching 45 degrees that are more of a concern. So what you propose should be fine.

I started working on mine last weekend, but it took a whole day to cut down the 40 x 40 box and re-weld it into a 40 x 10 profile -- very hard to keep it straight even with plenty of tack welds and butt welding on alternating sides. So I only got the BB Mount and half of the drive train done so far, but I should get a lot more done next weekend. It is very exciting seeing it come together.

The 1.6 mm rods are much harder form me to weld than the 3.2's I normally use. They flex very easily and quiver about so its harder to weld a nice straight bead. Even on my welders lowest setting, if they stick, they glow red in seconds and burn off the flux coating. But after a bit of practice I have mostly got the hang of them.

I am working on a proper web site for my domain, so I will post some pictures and a blog when I get it done, plenty to do...

-h
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