Why Titanium?
It
seems to be assumed knowledge that in the bike industry certain
materials are superior to others for building frames.
Titanium has certainly received a lot of attention and press in
the last few years, and few of us would argue it as being unworthy.
But how many of us can list its advantages over its competitors?
We have all heard the hype, but it can be difficult deciding what
to believe once the marketing machines get started.
For those who want concrete facts, here is some metallurgical
information to support the choice of titanium.
Titanium
is extremely resistant to corrosion.
This property has lead to titanium’s use as storage containers
for caustic materials in the chemical industry.
For you as a cyclist, this means that all the salty roads, messy
mud and stream crossing you ride over or through will not rust your
bicycle, ever. Titanium frames are lifetime frames.
The
density of titanium is nearly twice that of aluminum (though aluminum is
the weaker of the two metals), but only 56% the density of steel.
The stiffness of titanium is also about half that of steel.
It therefore follows that the stiffness-to-weight ratio of the
two metals is nearly the same. In
English this means that titanium is nearly as strong as, but is lighter
than steel.
Elongation
numbers of a metal tell us how much a material will bend before it
breaks. Titanium’s 20 –
30 % elongation beats out steel’s 10 – 15% and aluminum’s 6 –
12%. The lower the
elongation number, the more brittle and breakable a material is.
The higher the elongation number, the stronger the material is.
So, the same amount of titanium stretched out into a tube will
wear less than the same amount of steel or aluminum stretched out to the
same size tube. Carbon
fiber does not stretch; it must be molded into form.
Fatigue
strength is another measurement taken to compare metals.
Fatigue is the result of accumulated wear from repetitive cycles
of force. Aluminum is
notorious for having such a low fatigue strength that there is no
threshold, no level of strain below which the metal will not fail.
This means that the strain on a bike frame from each pedal stroke
contributes to the frame’s fatigue failure.
The effect can be delayed by over sizing the tubes to add
stiffness, but the tubes end up being very thin walled and give a
bone-jarring ride. In
comparison, titanium has a threshold below which it will never fail, no
matter how many times the cycles of force are applied.
Yes, this means that titanium will never fatigue and never fail
as long as the load it bears is below a certain level (which the stress
we put on it riding is).
You
are probably wondering by now what the catch is.
Can titanium be the wonder-metal it seems?
A look at the price tag of a titanium frame indicates that cost
is the prohibitive factor. The
high cost of titanium is not due to scarcity of the material, but rather
the processing involved in both extracting and manufacturing the metal.
Titanium is actually highly abundant, being the fourth most
available element in the Earth (after aluminum, magnesium and iron).
The process of extracting the metal is costly and requires a
great deal of energy. The
processing requirements are cost-intensive also.
Titanium has a reputation for being difficult to work with,
though perhaps it is more accurate to say that it is more particular
than other metals and requires meticulous procedures, making it
time-consuming and labour-intensive.
The bicycle industry first saw use of titanium in the 1970s.
It has taken some time before we have seen quality craftsmanship
in its use.
So now
you know the logic behind the claims of titanium as an ideal metal. The next step is to go out and ride one and see for yourself
how titanium compares to other frames out there.
Read our customer
feedback on our bikes.
