eBike Frame Material Overview: Steel, Aluminum or Carbon?


An eBike Frame Could Look Like a Simple Structure but How Its Building Material Affects the Ride?

Don’t know much about ebike frames? It means you may not be ready to buy the right electric bike.

One of the first considerations when buying one is their frame material and geometry.

That means you cannot move ahead and consider about other things you may want fit in such as a locking device or the addition of an electric bike suspension system.

 

Read More: eBike Anti Theft Locking Systems Guide and Electric Bike Suspension System Guide.

 

What could be the best scenario for some riders?

  • Cash-strapped aspiring racers would do well to go for an aluminum frame.
  • Those who can afford to spend a few more bucks would be better served by carbon.
  • Steel deserves your attention if you can do with a frame’s heaviness (and a few other drawbacks) in return for a smooth ride.

Which of them should you go for? That’s what this article will guide you about.

We’re going to do that by highlighting the pros and cons of these three (3) electric bicycle frames.


Steel eBike Frame

Back in the days, these type of material was the one ruling the industry. Sturdy and reliable. But as things were evolving, it was not so valuable afterwards.

It is actually very rare to see electric bicycles with a steel frame.

The bike now using steel are considered vintage.

Vintage steel frame - photo by Nick Fewings
photo by Nick Fewings

Advantages

One of the biggest benefits steel frames offer is an enhanced user comfort over long distances.

They provide springy ride quality and do a fine job of absorbing road vibration, especially as the tires roll over potholes or road cracks.

Steel is easy to repair too.

It is also very durable, despite of its resistance towards corrosion above par. All of these are the reasons why this type of frames are a must-have for any electric bike user who places their comfort above everything else.

 

Disadvantages

There are two (2) reasons why steel frames fell out of fashion after the 1970s.

The first has to do with their massive weight.

Steel weighs considerably more than both carbon fiber and aluminum. Thus, it can’t be used in racing or for mountain biking.

The second reason is that when you pedal hard on a steel frame, all of your added efforts won’t go towards making the tires roll faster.

Instead, some of it would be wasted in the flame’s lateral flexing, which is the movement of the seat tube and the head tube relative to each other.

This sideways movement of steel frames might be too little to notice at low speeds.

But it has the potential to make the bike unstable when you’re pedaling hard. That is precisely the reason why experts caution high-speed racers against using steel frames.


Carbon eBike Frame

Advantages

Most road e-bikes like the Bianchi Aria e Road, and higher-end e-bicycles use carbon fiber frames these days.

Carbon fiber is made mainly by bonding multiple sheets of this material in a mold with the help of a resin.

Although the above is the most common process, it could be also done by weaving carbon into a textile before applying a plastic resin on top to turn it into a composite.

ebike frame made of carbon photo by Jordan Brierley
photo by Jordan Brierley

One of the significant benefits of this material is that it is much lighter when compared with steel or aluminum, and resists corrosion better.

Its lower density helps carbon fiber provide a comfortable ride, as the added stiffness helps it absorb road vibrations with ease.

And the best thing about carbon fiber? It can be molded into complex shapes that aren’t just possible with other frame materials.

This property of carbon fiber gives electric bike manufacturers and shops more design leeway – which they exploit by making the frame as aerodynamically efficient as possible.

That is why carbon fiber bikes experience less drag at higher speeds.

 

Limitation

All the advantages of this material you saw above comes with a fee.

While their prices have come down in recent decades, carbon fiber electric bikes still cost more than their aluminum counterparts.

And their massive asking price isn’t the only shortcoming carbon frames suffer from. They are much better at hiding their defects in the aftermath of a crash.

Therefore, if your carbon frame has suffered a heavy crash and shows no signs of it, it doesn’t mean that there’s nothing wrong with it. It only means that you should assess it more carefully.


Aluminum eBike Frame

Advantages

Aluminum frames were the go-to choice of bike manufacturers before carbon fiber became more accessible.

They are relatively lightweight when compared with the other two above. These frames are also made of a stiff material and are available in ‘butted’ form.

The greater the butting, the better the frame is.

Single butted frames are thicker at one end, double-butted frames are thicker at both and triple-butted frames have a thin layer in the middle of two thicker ends.

This allows this frame to boast an excellent stiffness to weight ratio.

Yet another benefit of aluminum frames is that, while easy to dent, they aren’t as likely as steel frames to fall apart entirely.

ebike with aluminum frame - photo by Tower Electric Bikes
photo by Tower Electric Bikes

Throw into the mix their competitive asking price – as aluminum frames are cheaper to produce, and you get to know why road and criterium racers prefer them.

 

Disadvantages

The major shortcoming of this material is that it can provide riders with slightly harsh ride quality.

That’s because it doesn’t absorb road vibrations as well as the other frame materials.

Regardless of the above, I believe that there is a big reason why 95% of the eBike manufactures use this material.


Frequent Asked Questions

Q: Are carbon bikes faster than aluminum?

Experts tell us that electric bikes with carbon fiber frames are faster than aluminum ones because they have a more aerodynamic design that helps them experience less drag at higher speeds.

 

Q: How do I know if my carbon bike’s frame is broken?

Take a dollar coin or a key and start tapping on the doubtful area.

Areas that aren’t damaged will give the typical ‘tap’ sound. Those that are impaired will give off a dull thud.

Apply force on the suspect area and check whether it’s softer than the area around it.


eBike Frame Wrap Up

As you have seen, the frame of an electric bicycle can affects the overall performance when riding (e.g; sturdy, lightweight, durable?).

I know this is something really consumers don’t look at, and at some stage, there will be disappointment.

As an example, my bike’s frame is made of steel. Why did I choose it? The price was low and the ironic idea to be stolen on the streets.

Steel, aluminum or carbon, no matter what sort of material is selected by the manufacturer to design the frame as long as it offers what you need.

At the end, I believe the price tag should not be in the way of having a lot of benefits from the right ebike frame.


 

Paul T

Hi all! I'm Paul, founder and driver of Electric Bike Advisor (EBA). Learning from scratch by repairing and putting together my standard bicycle, I thought it was time to know more about the electric world. Enjoy reading my most honest point of view through our reviews, and learning from our guides, which are researched by professionals in the industry.