|
July 6, 2003 |
|
Picking up where we left off. Having
purchased most of the VK parts, I must decide what elements I want to use
and what I want to change. I am still very impressed with the weight and
workmanship of the frame and secondary elements, but I want a bike that does
not deviate too drastically from the "lowracer" configuration. I want a bike
that is close to what I already ride, i.e. the Optima Baron, and my Baron
Clone. I still can't get away from this configuration.
One element that I have always wanted to
modify was the seat I have been using. Studying the RazzFazz design. I am
convinced that the dorsal area of a seat must be more upright. So I will do
my best Thomas Schott impersonation (one of the RF designers) and modify a
seat. This will be the first element I will address.
The next element is what fork
configuration to use. I have purchased from VK both the mono and offset
fork. In addition, I am also was satisfied with the modified fork I used on
my Baron Clone (BC). This was a cut down 650 fork made into a 20 inch. Very
light, aero and functional. Although there is some chain line interference,
I have not found that to be a problem, even after many thousands of miles.
Another item is that of an adjustable boom. I strongly believe that the boom
must be adjustable for a myriad of reasons. With that being said, here is
where I am in the VK building cycle. The seat construction is the first item
to be discussed. |
 |
 |
 |
|
The stock optima seat was used as the
basic model. A fiberglass impression was made of the top of the seat, and
also of the bottom. A piece of wood was bonded to the top with the new
curvature I desired. This was easy to do since the top impression is only a
few plies of fiberglass, and bends easily. The bottom impression, however,
has the strengthening channels and must be cut to achieve a new curve. On
the bottom portion I filled in the strengthening channels with Bondo for
stability. I scribed transverse lines to show where the channels were to be
cut so that it will achieve the same curvature as that of the upper half. |
 |
 |
 |
 |
|
The bottom half was sliced with a saw
along the scribed lines where cuts were desired. Note that only the channels
were cut. The bottom half was then easily rotated to match the curvature of
the upper half. Wood wedges were then put in to set the new curvature, and
the voids filled with epoxy to form a solid structure with matching
curvature to both top and bottom half. |
 |
|
The new top and bottom halves of the new
seat were then bonded together. Then a great deal of surface filling,
sanding and smoothing made it into a viable mold form. After waxing and
buffing, top and bottom half parts of carbon fiber will form the new seat. |
 |
 |
|
These photos show the difference between
the stock Optima seat and the modified seat. The modified seat is more
upright in the dorsal area. The might negate the need for a headrest. Please
note that I never intended this to be a seat that would be used for racing,
as I am not a racer. Rather for those who ride lowracers and use them in a
practical, urban environment. |
 |
 |
|
Just for comparison purposes, the seat
plug was put on the VK frame to show its position in relation to the stock
Optima seat. |
 |
 |
|
After many layers of wax to the modified
seat plug, carbon impressions were made of the top and bottom. The top and
bottom impressions were then bonded together to form a seat. I was satisfied
as the weight came in at just under 500 grams, which was less than the
drilled out Optima seat. I took great care to remove as much resin as I
could in the lay-up process. |
 |
 |
 |
 |
|
The next project was to construct a clamp
for the boom to vary the length. I strongly think this is necessary.
Something so simple as changing the seat pad usually means changing the boom
length. I finally came up with a
design that I am satisfied with. I wrapped one layer of 6-ounce carbon cloth
around the bike nose. After curing, I removed this single layer. I then cut
strips of .100 carbon plate and bonded them to the bottom of the impression,
on the right and left sides, separated by a .375 inch piece of wood, which
was to be removed later. After shaping the bottom sides, I wrapped 2 layers
of heavy unidirectional carbon around it. Then I sanded, shaped and cut off
unwanted material. The resultant piece was drilled and slotted for 3 bolts.
It weighed 40 grams and will be bonded to the end of the frame. |
 |
 |
 |
|
After bonding to the frame, filling,
sanding, shaping and a preliminary paint, this is what it looks like. |
 |
 |
|
The next decision point is the choices of
a front fork/wheel combination. I purchased a VK offset as well as a mono. I
do not plan at this time to use the mono. In addition, I modified another
carbon 700 fork in case I do not use the offset. This is in addition to the
one on my BC. Shown is the VK offset with a Velocity 32-hole rim with a
Machine Tech hub. Also shown is a modified 700 carbon fork cut to a 20 inch
size (80 mm hub width) with a 18 spoke M 5 Hub and a Sun M 14A rim. The VK
fork weighs is 775 grams, the latter weighs 550 grams. Some 225 grams
lighter. In addition to the weight, the VK makes the BB much higher. This
will be shown in the following photos. |
 |
 |
|
These are photos of the frame with the VK
offset fork. Please note that the stock Optima seat is on the frame. With
this fork/wheel configuration, the seat height is 12.375 inches high and the
bottom bracket is 21.5 inches high. I will probably not initially use this
setup. |
 |
 |
|
These are photos of the frame set up with
my modified fork and the Sun M14A 18 spoke wheel with an 80-mm wide hub. The
seat is also the stock Optima Carbon large. The seat height is 11.5 inches
and the bottom bracket height is 19.625 inches. This will probably be my
setup of choice because it is lighter and the geometry resembles my Baron
and BC more closely. |
 |
| This is a photo of the frame
with the modified fork and wheel, but with my modified seat. Note how the
rider, while reclining the same, has an upper body configuration which sits
more upright. |
