Do Aluminum Bikes Corrode?

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Bicycle Universe - Do Aluminum Bikes Corrode

One of the biggest challenges for bike owners is trying to keep their bicycles from the effects of corrosion. Corrosion happens due to exposure of metals to elements and leads to the deterioration of metals and general bike performance.

This is why bike manufacturers are using different metallic elements for bike frames to try and manage this phenomenon.

So, do aluminum bikes corrode? Aluminum bikes do corrode; but unlike other metals, they do not get adversely affected by the corrosion. Exposure to air leads to the formation of aluminum oxide, a very thin film that protects the metal underneath from further corrosion. The aluminum frame doesn’t disintegrate over time; the only noticeable effect is a slight discoloration on the frame.

In this article, we shall consider how aluminum bikes react when exposed to the elements and their susceptibility to corrosion.

Bike makers use different materials for the construction of bicycle frames and each possesses unique benefits and disadvantages.

Aluminum is one such material that has over the past few years been applied for bike frames, gaining traction among consumers. In fact, with the majority of bike makers now using aluminum and its alloys in a number of their products, aluminum bicycle frames have become a mainstay in the world of cycling.

Unlike your average steel bike frames, aluminum frames are not vulnerable to rust and subsequent corrosion. This resistance to rust is what makes aluminum bikes low-maintenance and perfect for mountain biking, hobby and touring cyclists who spend a significant amount of time riding in wet conditions.

Due to their lower strength when compared to steel and carbon fiber, aluminum bike frames tend to have thicker walls. And although this may not necessarily give them an advantage over the other types of frames, manufacturers can use unusually thicker bike frames without increasing the bike’s weight.

Understanding Corrosion

As time flies by, most metals tend to experience deterioration as a result of corrosion which is usually manifested on the metal in the form of cracks, pits, or other forms of surface degradation.

Corrosion usually occurs as a consequence of chemical and electrochemical reactions that break down protective oxides- this is common to most metallic surfaces. Getting exposed to certain liquid, solid or gaseous agents like water, acids, water vapor, salts, bases, ammonia, and heavy metal ions may bring about corrosion.

Some metals such as steel are more prone to corrosion than others like aluminum. This all is dependent on their position on the periodic table and their electromotive properties.

Aluminum’s Property to Naturally Resist Corrosion

Pure aluminum is resistant to corrosion. This is as a result of the metal’s tendency to form a very thin protective film of hydrated aluminum oxide on the surface once exposed to air. The oxide film is normally around 2.5mm thick when it forms but thickens gradually with time.

If you dip aluminum metal in pure water, you will notice a white hydroxide film that maintains its thickness once equilibrium is reached.

Aluminum’s resistance to corrosion when it comes into contact with fresh or tap water will depend on the content gases, solids, or colloidal matter that has been dissolved in the water. For instance, a combination of chloride, carbonate, and copper will cause the water to be more corrosive.

Even the cheapest brand of aluminum bike does not rust! Aluminum is a self-protecting metal; the oxide that forms on the metal surface when exposed to air shields the metal underneath from the effect of corrosion. You can even throw a piece of aluminum in seawater and it will not have rusted after weeks in the water.

It takes very aggressive chemicals that are not ordinarily found to attack and destroy a piece of aluminum to the core.  Besides, the aluminum oxide forms within minutes of exposure to air so there is no time for the slightest damage to occur.

Does Aluminum Rust?

You might have noticed that most people assume that rusting and corrosion is one and the same thing; but is it?. To answer this question better, let us consider the actual meanings of the two terms.

Corrosion

Metals oxidize when they are exposed to air. This implies that they react with oxygen in the air to form their respective metal oxides. Corrosion sets in when the metal continues to oxidize over time. This result in a deteriorating metal that keeps on weakening as the whole of it becomes a metal oxide.

Rusting

Rusting is a chemical process that takes place when metals containing iron react with moisture and oxygen to form an oxide. In other words, rusting is a form of corrosion that occurs when the metal involved is steel or iron.

From the above explanations, we can conclude that aluminum does not rust as rusting only happens in steel and iron. However, aluminum is prone to corrosion which results in the formation of aluminum oxide- a very tough compound that shields the aluminum underneath from further corrosion.

The aluminum oxide also closely resembles the actual aluminum metal; it has a dull gray to powdery white color. This makes it not easily noticeable like you would with rusted iron.

When iron/steel corrodes, the color changes to a reddish-brown and the metal actually expands. The expansion and color change produces the red flakes that we commonly refer to as rust.

Contrary to what happens to aluminum, the expansion and subsequent flaking off of rust are what exposes the metal underneath to further rusting. This is why a coat such as of paint is normally used to prevent rust from setting in.

Although aluminum doesn’t rust, it usually turns dull as a result of the corrosion. This is usually encrusted with calcium, lime, brake dust, grease, oil, tarnish, and hard water stains.

Trying to wash it will not work, it requires something stronger to remove the (surface grime) and get the job done.

What makes Aluminum Bikes Popular?

Outside of carbon-fiber, aluminum is arguably the most preferred material for making bike frames for leading manufacturers.

While we have established its corrosion resistance property is one of the reasons that make aluminum the preferred metal, the following are other positive qualities it possesses:

  • Light-weight

    Aluminum is the most widely used lightweight material for bike frames. When compared to the most common and oldest material, steel, aluminum actually weighs three times lighter.

    Although manufacturers have of late modified steel bikes to achieve a low weight, aluminum bike frames don’t require any design alterations to remain light-weight. Due to this, it has remained a popular frame material option for race and mountain bikers.

  • Very Durable

    Aluminum is a very durable material! The fact that it does not yield to the effect of corrosion ensures that it can be used for the long haul without disintegrating.

    Even when it is used in wet and salty conditions, it doesn’t corrode like your average bike frame material.

  • Quite Stiff

    The stiffness of the bike frame material affects the feel of the ride by providing stability when ascending a hill or sprinting.

    Aluminum bike frames are generally stiffer when compared to other materials, making for a non-turbulent ride if you are a mountain or race biker.

    Given the little sway in aluminum bikes, the bicycle remains relatively calm and stable when negotiating bumpy or rocky terrain.

  • Reasonable Cost

    Although they are more expensive than the more common steel frames, aluminum bike frames are relatively inexpensive.

    Considering the many benefits that they offer, these bikes actually offer great value for money.

    Well-rounded, light-weight, and affordable; aluminum bikes make ideal choices for bikers at all levels of expertise.

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