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Once upon a time, bikes and components were made primarily out of steel. Then aluminum came along and became the material of choice for cycling industry designers. More recently, the buzz has been all about carbon. Yet despite the hype, carbon isn’t the best choice for every application, and aluminum continues to play an important role in cycling. 

Looking Back

Steel has always had its advantages. At approximately 2.5 to three times the density of aluminum, it’s is a stronger material, and even considering the fluctuations in the prices of raw materials over time, it’s generally cheaper to make something out of steel than out of aluminum.

Nonetheless, aluminum started making its way into cycling in the 1970s and became more ubiquitous in the 1980s as engineers honed design and manufacturing processes. So why did aluminum become so popular?

Aluminum appealed to cyclists largely because it’s lighter than steel. That weight adds up when you consider not only a bike’s frame, but also its components. And who doesn’t enjoy riding and especially climbing on a lighter bike?

Aluminum is also inherently more malleable than steel. That means it can be made into more complicated shapes – think intricate frame designs. It’s also more resistant to corrosion without any extra special treatment: it doesn’t rust. That means you don’t have to coat it or paint it or worry if you scratch it, which is great for bikes that are often ridden outdoors in wet or humid conditions or offroad.

Looking Forward

With the increasing popularity of carbon for frame and component materials since the early 2000s, it may seem like aluminum is going the way of steel – to a much lesser prevalence in the cycling industry. However, while carbon is extremely light and rides well, it is both more expensive and more fragile than aluminum.

So even as we see high end road and mountain bikes increasingly going with more and more carbon, aluminum is still a solid choice for entry level and mid-level bikes. Many brands currently offer both carbon and aluminum versions of popular frames to meet a range of different price points.

Assuming that the price of raw materials and manufacturing process for carbon and aluminum don’t change substantially relative to each other, aluminum should continue to be an important part of the cycling industry moving forward.

When it comes to components, the same thing is true: many top brands are making carbon and aluminum versions for the exact same reasons: durability and cost. Yet some are still betting largely on the successful future of aluminum.

Working with Aluminum

As aluminium product manufacturing and finishing techniques become increasingly more automated over time, manufacturers have been realizing goals of less waste, faster production times and higher quality – all of which translates into lower costs. Its manufacturing can easily be done in-house with the appropriate equipment; unlike carbon, it does not have to get outsourced to a specialized manufacturing facility in an often far away place like Asia.

Furthermore, aluminum frame design is becoming more sophisticated. Long gone are the early days of thin aluminum straight gauge tubes mechanically glued or screwed together and the subsequent days of framesets with big, fat aluminum tubes. They, respectively, produced frames that rode too flexy and too harsh. Modern designs create aluminum bike frames that give a much more comfortable ride.

Today, there are a few common ways of making parts out of aluminum. One is hydroforming, or using hydraulic fluid to press aluminum into shape. Shimano is famous for using forging methods whereas ROTOR has invested heavily in CNC machines. Both brands have been loyal to making parts out of aluminum for decades. ROTOR, in particular, comes from a strong background in aeronautical engineering, an industry with extensive aluminum manufacturing expertise.

An advantage to CNC machining is that its equipment can be easily reprogrammed so as to be able to make a variety of different parts. That’s especially useful to a component manufacturer like ROTOR that needs to make everything from chainrings to power meters to brakes.

Take a tour of ROTOR’s factory

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