There are many types of materials used to make mountain bike frames, with the four most popular being
aluminium, steel, carbon and titanium due to their properties and availability. The choice of material
will dictate the actual frame design, as different designs are more suited to the capabilities of certain
substances. Each material has its own properties and effect on the rider's riding experience, as well as
its own price range. For these reasons and more, most riders develop a personal preference.
Steel
Steel was traditionally the most common bike frame material, dominating the market for many years before
technological advances made aluminium cheaper and easier to produce. One of the common complaints with
steel is that it can be very heavy compared to other options, but it is also very strong and has a
natural compliance that can give a more comfortable ride.
Less expensive and milder steel requires more thickness for the walls of the frame to be strong enough.
This adds noticeable weight to the bike, so a high grade of steel makes a big difference to your ride.
Choose 4130 chromoly for all round durable strength and precision grades from companies like Reynolds
and Easton for added strength and stiffness, allowing for a lighter weight frame.
Whilst steel frames look good and can be easily repaired, they are of course prone to rust if not cared
for and stored properly, so these days quality steel is often the choice of purists and retro cyclists,
although lesser quality steel is still common on cheap, heavy bikes.
Aluminium
Aluminium is one of the best value frame materials. It makes the frame light but very stiff. A lot of
professional level frames use aluminium because it can be easily manipulated to create aerodynamic designs,
and modern techniques mean it can be formed to make the frame material thicker in areas of stress or
where greater stiffness is desirable, such as in the bottom bracket area. Another bonus of aluminium is
that it doesn't rust. It does suffer from metal fatigue though and has a lower life expectancy. It is
also a notionally weaker material than steel and titanium, meaning it is at more of a risk of breaking.
When it does fail it snaps or crumples rather than simply bending like steel, so is harder to repair.
Titanium
Titanium bike frames are perhaps the most resilient. Nowhere near as dense as steel, so you get a strong,
sturdy bike frame that is light too. Whilst it is not as stiff as steel, light frames can be made strong
and stiff enough to cater for larger riders. Titanium is also rust-proof and is much less at risk of
suffering metal fatigue. Although titanium is in many ways a far superior material than steel or aluminium
it is also more expensive to produce and more difficult to work, so the raw materials and manufacture both
cost more and the resulting expense makes it impractical for the mass market and it remains the remit of
a few Ti specialist producers.
Carbon Fibre
The introduction of Carbon Fibre to bike frame technology has been very important. It is four times
stronger than Steel of the same weight. The strength and stiffness of carbon fibre bike frames is very
controllable, as it is very easily moulded during production, so is stronger than steel and more versatile
than aluminium. The risk of fatigue is virtually zero, and with its low density and high strength level,
very strong light frames are possible. These points combined with the fact that it looks good and cannot
rust make it an extremely successful bike frame.
Its stiffness even allows it to absorb vibration very effectively to provide added comfort and reduce
numbness on a long ride. The main downside is the cost. It is the most expensive bike frame, but you
certainly get your money's worth.