feaatures of electric bike frame

Electric Bike Frame Explained

by

Noel Joseph
August 24, 2021
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If you’ve looked at electric bikes online, you’re going to notice a few things that really tend to differ from traditional bikes.

One of them is the frame, and that’s what we’re here to talk about today. Electric bike frames can look bulky, oversized, and particularly heavy, but there are reasons for any initial impressions you may have about them.

Most electric bike frames are designed to house a battery inside of them, which is why some of them appear thicker than others, and why you may not see a separate aluminum power bank attached to the top portion of the frame.

We’ll talk about all that, and more.

Parts of an eBike Frame

key parts of ebike frame

Your frame consists of multiple parts, and to understand why ebike frames are the way they are, you need to know about each of them.

  • Handlebar Stem: This isn’t exclusive to ebike. This is the long piece of metal that goes down from the handlebars and generally attaches to the wheel hub. This may look different depending on which electric bike you choose, as some hub motors can be found in the front as well. These will attach to the wheel, and may change the appearance of how the handlebar stem attaches to the entire system.
  • Down Tube: As you might expect, this is the metal tube that travels down from the handlebar stem and extends to the bottom of the frame before it extends to the back of the bike. Your down tube is the most important part of your electric bike, because it will either house the battery inside, or it will act as an anchor support for the battery bank which will be attached to the top or bottom of it depending on the design of the bike.
  • Top Tube: This varies depending on the style of the bike, but to keep things rigid and stiff, it usually runs pretty high. This is also where you can find the battery housing attached in many circumstances, and of course it depends on if it’s being housed inside, or on the battery bank total size.
  • Seat Tube: The seat tube is what extends up from the bottom of the bike where it meets the wheels and the chain. It’s no surprise that this is where it attaches to your seat, but it also runs along your rear motor as well. These tubes don’t typically need to be super thick or anything like that, but you should.
  • Seat Stay: This runs from the back of the seat tube near the top, and meets the chain stay in a triangle towards the back of the bike. This is the point where it attaches to your wheel. In MTBs you will notice that the hub motor sticks out a bit and the seat stay is mostly concealed.
  • Chain Stay: The opposite of the seat stay. This runs along the bottom and does what it says it does: it’s there for the chain to be attached to. Once again, a hub motor may cover this up a little bit.

How Does an eBike Frame Differ From Regular Bike Frames?

Because you can convert a manual bicycle into an electric bike, you actually run into a lot of situations where the frames are the exact same.

However, there are some unique differences in pre-built ebike frames compared to standard bicycle frames.

  • Weight: An ebike frame is made of heavier materials, so it weighs more, but it’s also designed to be like that without sacrificing power.
  • Bulk: They’re going to be thicker and harder to grab onto as opposed to thin aluminum poles in manual bicycle frames.
  • Design: They look vastly different in pre-made ebikes. You’ll notice a much more linear design with straight/square angles instead of circular tubes like you find in manual bicycle frames.

Best Materials for an Electric Bike Frame

materials for ebike frame

Typically, you want something that’s strong and lightweight. While those two attributes aren’t mutually exclusive, they’re also hard to marry to one another.

These are the best materials out there.

  • Carbon Steel: It’s commonly used in bike frames for being light and highly tensile, but also being affordable. However, it’s not the lightest thing out there for a bike frame, so depending on your preferences and what you want to see in your bike frame, this might not be the best pick.
  • Chromoly Steel: Light, strong, and great for agility. It’s more flexible than carbon steel, so you won’t see this used in electric mountain bikes as often as you should, but for commuting bikes that you want a high level of durability on, this material works wonders.
  • Carbon Fiber: These are bound fibers, not metal, so they’re going to be strong but have a low weight threshold. These will be seen in folding ebikes more than any other type of bike for their lightweight use.
  • Titanium: It’s a lot lighter than steel, but it’s highly expensive in comparison and not as powerful. You’ll notice that titanium bike frames are not in high demand, and are overpriced despite their fragility. This is more likely to be seen in manual bike frames, no ebike frames.
  • Aluminum: Perhaps one of the most common manual bicycle frames out there, aluminum is inexpensive, but other than that it doesn’t provide too many benefits over other materials. It’s strong enough to get the job done and fairly light, but that also means it has a lower weight threshold.

How to Spot the Best Frame

how to spot best ebike frame

By looking at the materials, and being able to test the frame to the best of your ability.

If you’re thinking about buying an electric bike, you first have to give it a test ride and feel how it responds to your rider weight, and any strain that you may be putting it under.

Most bicycle shops will allow you to do this, but let’s be honest: it’s 2021, and shopping online – even for high ticket items – is becoming a normal way to get electric vehicles. Looking at you, Tesla.

So what else can you do? Spotting the best frame requires you to:

  • Look at the total weight capacity for the entire bike. You should be able to see a maximum user weight on any sales page. The lower that number is, the weaker a frame (and other components) of an electrical bike will be.
  • Read user reviews from third-party websites. These could be forums like Reddit or something along those lines, but you don’t want to put too much stock in the reviews that a manufacturer hosts on their own website if you can avoid it.
  • If the frame houses a battery bank, then the frame itself has to be somewhat resistant to being heat conductive. Batteries can begin to run hot, so the frame needs to handle that without burning the leg or hand of the bicycle user. If a company houses the battery inside of a rather thick frame, then they’ve either made the metal so thick that heat can’t penetrate through it under normal circumstances, or the frame is designed to disperse heat, kind of like a heat sink. Either way, look out for anyone complaining about overheating in these types of frames.
  • Folding frames. These are going to vary, and it’s manufacturer-based, but thankfully we have an entire article talking about that.

Are Folding Ebike Frames Fragile?

are folding ebike fragile

Any time you introduce a hinge or joint to something, it can surely become more fragile, but this is not inherent.

Manufacturers understand that this is going to be an issue for many people, so they go the distance and ensure ebike frame quality from the start.

The frame quality is important, but hinges and joints also need to match up, be nice and wide, thick, strong, and thoroughly make the rider feel completely safe at every point of travel on their electric bike.

This isn’t something you really need to worry about, as long as you pay attention to the manufacturer that you’ve chosen and know what to expect from them based on reviews and user experiences as well.

Spotting a Stronger Bike From the Start

Apart from being designed with the battery housing in mind, you’ll also notice that electric bike frames are solid, strong, and designed to last.

There’s increased stress on every part of an electric bike because of the speeds it can achieve, and the increased weight, so having a good frame is important.

Thankfully, all electric bike manufacturers that we’ve seen have been able to make solid, powerful frames without any real issue. The only thing you have to pay attention to is folding ebikes and their frames, but we’ve also covered that in another article you can find right here.

Now that you know what you’re looking for, it’s time to start hunting down the perfect ebikef or you.

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Noel Joseph

Noel Joseph has been in the world of motor vehicles for a long period. Currently, he is enthusiastic about Electric & Hybrid Motors and is an independent researcher. He advocates for a clean and sustainable future and envisions utilizing his years of experience in mechanical engineering. His new venture here at CompactPower.com is to organize and simplify knowledge on Electric vehicles. He wants to build a space where people can talk about EVs and associated technologies with freedom.