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The bicycle wheel is a beautifully efficient structure...
It is a relatively lightweight component, yet it
can support tremendous loads. Although the basic design has not
changed much over the past century, we decided to use our
knowledge of the latest composite materials and rethink the
design, using these materials in a whole new way.
Taking advantage of today’s materials...
For the spokes, we use a hybrid construction with
Kevlar fibers alongside carbon fibers, all within a
thermoplastic resin matrix. The carbon fibers provide superior
stiffness, while the Kevlar adds tremendous toughness.
This unique material is incredibly strong and fantastically
light. Topolino’s composite spoke material is stronger than a
14g stainless steel spoke and is only one-fifth the weight.
And light weight is only part of the story: the thermoplastic
resin and Kevlar/carbon fibers work together to significantly
dampen road vibration, for a difference you can feel.
We also use a special thermoplastic carbon
fiber composite material for the hub shell. It has strength
matching that of aerospace aluminum, but is 45% lighter.
But materials are only part of the story -
getting the true performance out of these incredible materials
required a whole new approach to wheel construction.
We go all the way…
Rather than interrupting the Kevlar and carbon
fibers, each spoke spans diametrically across the whole wheel.
This reduces spoke stress at the hub and allows the continuous
unbroken fibers in the spoke to span clear across the wheel.
With conventional steel spokes, the spokes are not well matched
to the hub flange. As any wheelbuilder knows, steel spokes must
be manually bent near the flange and forced into alignment to
direct the spoke toward the rim.
This creates a flex point in the spoke and it is this flex and
squirm of that is one of the main causes of spoke breakage due
to fatigue.
In contrast, the Topolino hub is molded around the spokes to
fully support and align each spoke within the hub flange. The
spokes are held in pure tension, with none of the
fatigue-inducing movement or flex that is characteristic of
conventional steel spokes.
Balanced construction…
Because the current nine and ten speed cassettes
take up even more real estate on the rear axle, the rear hub
flanges have an unbalanced offset as compared to the rim
centerline. The result of this offset is a significant
difference in spoke tension between the drive-side and non
drive-side spokes that is the Achilles heel of rear wheels. Some
designers have attempted to balance the tension by moving the
flanges closer together. While this may balance the tension to
some degree, the narrower flange spacing does nothing to help
the lateral strength and stiffness of the wheel.
At Topolino, we have chosen a different route. Our rear wheel
utilizes 50% more spokes on the drive-side flange. This creates
a far more balanced spoke tension and also significantly
improves the lateral strength of the wheel.
Sensible spoke count…
Since our spokes are so light, there is virtually
no weight penalty for adding a few more. This allows us to use
what we call a "sensible spoke count". We lace our front wheels
with 24 spokes and the rear with 30 spokes. As compared to the
current trend in low spoke-count wheels, adding a few more
spokes results in far better stress distribution around the rim.
We are able to use a much lighter rim for lower rotating inertia
while, at the same time, building a stronger wheel.
 Aerodynamics…
While our focus was to create the lightest,
strongest wheels on the planet, we paid close attention to
aerodynamics as well. So, we formed those special Kevlar spokes
into a bladed aero profile and we also use a semi-aero rim
section.
Not only are these wheels light, but they slice through the wind
as well.
Modular construction…
Even though we packed a whole bunch of technology
and innovation into these wheels, they were designed to be
repairable and to exist in the real world. The spokes and hub
are built as modular "wheel halves" that are laced to the rim in
a conventional fashion. This means that, if a wheel does become
damaged (in a crash, for instance), the individual parts are all
replaceable using conventional tools and the wheel may be easily
rebuilt to live again.
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