Framing Materials

The cost of a mountain bike frame is proportionate to
its material, as well as the treatment that material
has received.  Currently, there are five types of
material used in mountain bikes - high tensile steel,
chromoly steel, aluminum, titanium, and carbon
fiber.  Oversized diameters, heat treating, and butting are
tubing material treatments that will increase the
cost of a frame as well.

High tensile steel
This is a very durable alloy that's found in lower
priced mountain bikes.  It offers a high carbon content
which makes it less stiff than chromoly steel, so
more materials are needed to make it stiff enough for
bicycle frames, which will in turn make it that much
heavier.

Relatively inexpensive to produce, you'll find this
material in trail bikes, city bikes, and even entry
level mountain bikes.  There are some bikes that come
with a chromoly seat tube, while the rest is high
tensile steel.

Chromoly steel
Short for steel alloy, chromoly is best described by
its major additives - chromium and molybdenum.  This
is probably the most refined framing material, giving
over 100 years of dependable service. 

Depending on the type of heat treating and butting,
you can find this material in bikes as low as 400
dollars all the way up to 1,500 and beyond.  The
chromoly steel material offers very good durability
and a compliant ride characteristic.

Aluminum
For the past 15 years, aluminum has been refined in
pretty much the same way as chromoly.  There have
been various alloys developed, as well as heat
treatment, oversizing, and butting.  With dual
suspension bikes, aluminum is the preferred material
as it's the stiffest and most cost effective.

Aluminum is stiffer than chromoly, and therefore it
will crack before chromoly.  Of course, this depends
on how you ride and how much abuse you give the frame.
The advantages of aluminum is that the frame is very
light and very stiff through oversizing or butting.

Titanium
Even thought it's somewhat exotic, the prices for
this material have come down over the last few years.
Frames made of titanium remain expensive because it
takes longer to weld the tubes to the frame.

Titanium is considered an alloy, normally mixed with
small amounts of vanadium and aluminum to give it
better weldability and ride characteristics.  More
compliant than chromoly, it offers better fatigue
and corrosion properties. 

The material you choose for your bike, all depends
on where you ride and what style you use.  Almost
all materials will last you for years, as long as
you take care of your bike and treat the frame with
some respect.