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Our years of research have confirmed that bicycles undergo
a multitude of different forces when ridden, including;
torsion, bending, compression, tension, shear, and aerodynamic
to name a few. The location, magnitude, and
direction of these forces differ given the type of riding
being done. Further, within any given frame, specific
tubes will experience very different forces depending on
the type of riding being done. To successfully achieve the
desired performance target of the bicycle, the designer
must have a solid appreciation of what types of forces
exist, their magnitude, and their direction during the various
aspects of riding. The designer must also have a
clear understanding of how these forces travel through the
frame and how this path is altered as design changes are
made to a particular tube. Only with this information can
intelligent decisions be made as to what materials and
tube shapes best fit the application.
Graph A explores the magnitude of forces on individual
frame tubes and demonstrates how they can change
given the type of riding exerted on the frame.
Take for instance the change in force on the top tube during
hard braking as compared to sprinting/climbing. The
top tube is stressed 2.5 times more during hard braking
as compared to sprinting. The minimal role the seatstays
play until a vertical impact takes place is another excellent
example of just how much forces can vary as you change
riding styles.
In addition to understanding the magnitude of forces
placed on individual frame tubes, we also need to factor
in the effect that directional forces created under load will
have on a frame's performance.
Figure A depicts the direction of the forces generated
when a bike incurs a vertical impact load. In other words,
the arrows indicate what direction the different tubes want
to move when you apply a vertical impact such as bunny
hopping or rolling over the lip of a driveway.
Figure B shows the direction of the forces created under a
torsional load such as sprinting. The red arrows effectively
demonstrate the twisting loads placed on the individual
tubes and the yellow arrows demonstrate the bending
loads that occur at the same time.
The detailed stress analysis that we perform for every one
of our frames is a critical step in the frame design
process. It enables us to decide on what material we want
to use and where. More importantly it has given us the
information needed to create tubes that are stress-directional-
specific and work to counteract the various forces.
Geometrically Enhanced Tubing (G.E.T)
We have found that by creating very specific tube shapes
we can build frames that will better resist the various
types of forces generated in cycling. For example, a round
tube will better resist torsional or twisting loads, a rectangular
or square tube performs best against bending, and
a bladed design is excellent at reducing aerodynamic
drag. Given that any tube may undergo one or all of
these forces as riding style changes, it becomes obvious
that there is no one tube shape that is perfect for all
styles of riding. Round tubes make a very good bike, but
this single shape simply cannot efficiently address all the
different forces any given tube will be subjected to during
riding. A round tube will perform well as long as the
forces are purely torsional. But in reality there is no riding
circumstance where 100% of the force on a tube is entirely
torsional. Modifying the outside diameters and wall
thicknesses can offer improvements, but even then
compromises will have to be made.
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Litespeed combines all the data in each riding case and creates cycling specific geometric tube shapes for each part of the frame. Figure C shows examples.
Take for example, the Vortex top tube (Figure D). This diamond-
shaped top tube is designed with consideration
given to the specific forces that the top tube will
encounter. In this particular case the design parameter is
40% torsion, 55% bending, and 5% aerodynamic. This
combination is perfectly suited for the intended use of our
Vortex frame.
Likewise, the Vortex down tube (Figure E) is shaped to
engage 60% torsion, 30% bending, and 10% aerodynamic
forces. This provides a balance of stiffness for climbing,descending, and cruising that normal round tubes simply cannot match.
Each tube of each frame that Litespeed designs takes all
these factors into consideration. The end result is a wonderful
array of frame choices that address each individual's
riding styles and preferences without sacrifice.
Geometrically Enhanced Tubing is taking Litespeed to a
whole new level in high-performance bicycle technology,
one that imitators can only hope to follow.
Titanium Frame Fabrication
Titanium bicycle frame fabrication is a very difficult
process namely because the material itself is extremely
complicated to work with. It is extremely difficult to
machine, shape, and weld and there is literally zero tolerance
for error in any of the processes. Further, it requires
special dies, fixtures, expensive cutting tools, strong and
accurate equipment, and most importantly a great depth
of knowledge in how to use these tools to craft the world's
finest bicycle. In a nutshell, its complexity is the reason
there are so few titanium makers in the world. We know
because we've been custom fabricating titanium for over
40 years.
Cold-Working
Ironically, one of the properties that makes titanium so
difficult to work with is part of the reason it is the best
material for a high-performance bicycle frame. Titanium
reacts significantly to cold-working. Cold-working is any
process that permanently bends or alters the shape of the
metal at room temperature. This process actually increases
the hardness and strength of the material. This reaction
is commonly called work-hardening. The benefit to
the frame is an increase in strength without any gain in
weight, giving the designer the option of reducing the
overall weight should the increase in strength not be necessary.
It's All In-House
In order to keep all the complications of working with titanium
under control, we believe in the axiom "If you want it
done right, you better do it yourself". At Litespeed not
only do we build bicycle frames, we CNC machine all the
small parts of the frame such as drop-outs, bottom bracket
shells, cable guides, etc. We do all the forming, shaping,
and bending of every tube. We make all our own tooling,
dies, and fixtures. We even design and build much of
the equipment necessary to create bicycle specific titanium
tube sets. By doing all this ourselves we are able to
maintain the quality assurance necessary for our products.
This also gives us the added benefit of rapid and
efficient innovation. For example, if we need a change in a
tube shape, we have the ability to create the necessary
tooling literally overnight as opposed to the weeks and
months it could take by having it outsourced.
Our flexibility and speed in manufacturing is just one
example of how we are able to continually push the technological
envelope in bicycle design. Our dedication and
passion to always improve is what drives us every day to
build lighter, faster, higher-performing bicycles.
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