Building
A Custom Carbon Bike
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| May
27, 2002
For those who have been following
my experiences with both The Baron and the M5, you will know that I have
made the decision to build a custom carbon bike based on my experimentation
with a carbon fiber/expanding polyurethane foam construction. This was
shown on the Frame Concept page. My goal is to build a sub-20 lb. complete
bike. I made the specifications closer to the Barron/Jester configuration
because of my experiences with The Baron and the M5. I will give a better
explanation on the newsgroups page. Below find the start of the building
process and where I am now. |
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| Shown
above is a comparison of the Baron and the Jester. The wheel bases are
almost identical as is the fork angle. The Jester has a slightly lower
seat height, and the seat is positioned slightly more forward. Since I am
a tall person, I decided that the Baron would be more suitable. I plan to
make the frame and then add the rear fork after the frame is built. This
rear fork will also be made out of carbon fiber. The frame will be made in
a negative (female) mold so that multiple parts can be pulled from the
same mold. This is a very labor intensive process because it means that a
plug must be built and an impression made of that plug so that the actual
part can be made. This is a lot more work than laying carbon around a foam
shape, but it is a lighter method of construction, and the plys can be
oriented where the structure needs it most. |
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| Rough
frame. The dimensions for the frame were transferred to a right and left
side of four pieces of furniture grade plywood. On each side, I took a 3/4
inch and a 1/2 inch and glued them together. I did the same for the other
side. The 2 halves were then screwed together and the rough form was cut
with a jig saw. Each side had approximately 18 plys of wood which provided
a good visual reference when rough smoothing took place. After sawing from
the sheets of plywood, I made sure that all sides of the plug were 90
degrees to each other to ensure a smooth form. |
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| The
rough form is now in a final stage of sanding. I will not, however, know
the highs and lows of the form until paint is applied which shows off discontinuities.
I applied a first coat of deep penetrating epoxy and after cure, a heavy
coat of regular epoxy with filler material and black pigment. Final
sanding takes place with block from 100 grit down to 600 grit wet. |
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| Another
view of the rough sanded form prior to the finishing process. Shown are
the screws which hold the right and left halves together. In order to
prevent the halves from bonding together via the epoxy, the sides of the
halves touching each other were waxed. |
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| Shown
here is a final sanding of the epoxy. The black pigment aides in
determining highs and lows of the plug. Any imperfection is transferred to
the female impression and hence the part. Therefore, it is critical to
make a smooth flowing plug. |
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| After
final sanding of the epoxy, two coats of black lacquer and two coats of
clear were applied, with light wet sanding between coats with 1000 grit.
Shown is the front half. |
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| Shown
is the final plug relative to the Baron. |
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| Another
view of same. |
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| Frame
shown from rear. |
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| View
showing comparison with Baron. Next step is to split the two halves,
repair holes and damages, apply 4 to 5 coats of mold release wax and buff
to an ultra-smooth finish. Then mount two halves on flat boards. The
impression made with fiberglass will be next. |
