What size Electric Bike do I need?

This is one of the most common questions we get asked over and over again. To an untrained eye, trying to work out what size electric bike you need can be difficult. Brands size their bikes up differently to others. They may use a geometry table, they might show you sizes on a graphic, they might use cm, inches and to confuse you even more there are different frame styles to choose from too. It can be quite confusing. Lets breaks down the key points you need to know asking yourself what size electric bike do I need?

In my experience there are three ways to choose the correct size ebike in order of importance

  1. Take a Test Ride.
  2. Compare geometry of a new bike to a current bike you own.
  3. Work out what size you need from scratch.

#1 Take A Test Ride

The hands-down best way to help you choose the correct size ebike is to take a test ride. Whether you have an existing bike or buying from scratch, experienced staff will take your height and ask you some other key questions and very quickly narrow down your options for you to try. It will tick a lot of boxes for you.

  • Work out the correct size frame you need.
  • Feel how it rides with the motor assistance.
  • Give you the confidence it’s the right bike for you.

It’s important to understand that Brands quite often advertise different size bikes for effectively the same frame size. Let me explain.

Most brands will measure their frame sizes from the centre of the cranks (where the pedal arms attach to the motor) to the top of the seat tube (where your seatpost fits in and is clamped). For example, if the top tube is horizontal, this may measure, let’s say, 50cm. Another brand’s frame may have a top tube that slopes down slightly and measure 46cm (see illustration below). In essence, we have two different sizes for effectively the same frame size, and this is common and causes confusion.

If the top tube is missing (step-through or open frame) or much lower, Brands often use an effective top tube size. They still measure it like if it were there.

Don’t assume, Just ask

For this reason, I recommend you size yourself per bike, per brand. Don’t assume a size in one brand will be the same for another. I’d also recommend if the sizing is not numeric, ie Small, Medium, Large etc, you find out the numeric sizing that sits behind it and use that to compare. Use the experience of a retailer to help you. We are an online retailer, part of The Electric Bike Shop family, but the wider business has retail stores dotted around the UK to help you take a test ride too

#2 Compare Geometry

If you can’t get into a store to take a test ride, don’t despair you can still work out what size electric bike you need.

If you have an existing bike you ride that you find comfortable, you can use the geometry of that to find out what size you need. However there are caveats to this approach. Firstly, you must compare like for like, so don’t try to use the geometry of, say, a road bike if you are buying an electric mountain bike. Electric vs non-electric is fine as they are similar types of bike. Secondly, if the frame styles (eg Crossbar vs Trapeze) are different then comparing geometry charts will be of no use, you will have to default to taking some measurements yourself which I will now explain.

By Geometry Chart

If you can compare bikes using a geometry chart then there are two sets of measurements you can use depending on what the electric bike Brand uses in their data.

  • Stack and Reach
  • Horizontal Top Tube Length and Head Tube Length

You’ll see from the measurements that as frames get bigger they have a longer Reach or Top Tube Length. Additionally, a taller Stack or Head Tube Length.

By Self Measurement

If the frame styles are incomparable, let’s say a crossbar to a step through for example, then self-measurement is the way to go. Take a tape measure and measure the horizontal plane from the centre of the top of the head tube to the centre of the seatpost. Then measure the length of the head tube, top to bottom. You can use these to compare to the respective measurements in the geometry chart for your new bike and pick the closest match.

#3 Work Out Your Frame Size From Scratch.

If you can’t test ride a bike and you don’t own a bike to compare your new one to then you need to try and work out your correct size from scratch. Let me walk you through that process.

As a starting point use the brands size guide. They are usually available on their product websites. We have size guides for nearly all the Ebikes we sell. If not, go back to the brands own website and find one there. It may be a simple table, based on your height or more commonly these days they may ask you for additional measurements. Inside leg and arm as well as your height to try and be more specific.

These are guides though and should be treated as such. They are not absolute. Frame sizes will suite a small range of heights of riders without taking into account other factors like specific anatomy. If you appear to fall in the middle of the range, it’s probably your size. At the upper or lower end of the recommended height range then you will need to do a bit more research to work out if you need a bigger or smaller frame. If there isn’t a size big or small enough for you, just get in touch with us.


Further Reading


When I owned my bike shop I always used to say to customers they could be one of three sizes. The correct size for their height, a size up or size down because of other factors like anatomy or ailments. I’m 5ft 8 and often take a size smaller than my height normally dictates. I have a very short reach, so I always go for a shorter frame.

Final Word

Whether you are taking a test ride or talking to us. Before you decide what size electric bike to order, speak to us and confirm what size you think you need is correct. There are no hard fast rules here only a general guide but take the advice and use our experience for peace of mind. If you have the geometries, let us do the math for you.

The right frame size will give you years of pain-free, enjoyment. Take the time and effort to get it right.

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