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How do I know what size e-bike or s-pedelec to buy?

If you are returning or taking up cycling then choosing the right bike is a fundamental.

There are so many personal choices to consider, eg weight of frame, dropped handlebars or standard, step through or cross-barmore or fewer gears. Most of those are personal choice, but getting the right sized bike is important.

BUT, the correct size will depend on what you are using your e-bike for.

When you look at the listings on this site you will see frame sizes (normally stated as a S, M, L or a certain number of centimetres. The wheel sizes will be quoted either in inches or ISO standard sizes. There is also reach to consider, this is the distance between handlebars and the saddle).

Where do you start?


For the reach, this depends on your height, body length and if you want to sit upright whilst cycling or bend right over for improved aerodynamics. The saddle can be moved forward and back slightly on most bikes, plus the handlebars can be raised / lowered a certain extent by modifying the stack.

Frame Size

The frame size will depend on your height and inside leg measurement. Of course, the number of centimetres (or inches for mountain bikes!) is more accurate than S, M and L, as these can vary by manufacturer, just as clothes do. The frame itself is the distance between the pedal shank and the seat post. Some of the major retailers have look up tables to convert heights to frame sizes for different types of bikes (road, mountain, hybrid).

Seat Height

There is a simple way of ensuring the seat is at the right height for you. When against a wall, or someone holding the bike for you, put your heel on the pedal when it is at the 6o’clock position. Your seat is in the correct place when your legal is straight. Most seat posts will have markings so you can note the seat height for future in case the seat moves.

When you then put your foot on to the pedal normally, you will have a slight bend in the leg when at the 6 o’clock position so that the leg is not over-extended giving a comfortable position for cycling.

You should keep the seat level – that is how it is designed to be – but it can be tilted slightly if needs be.

On some mountain bikes the seats are on hydraulics and can be dropped when cycling down an uneven downhill to avoid the bouncing on the buttocks.

Wheel sizes

On a mountain bike the wheel size tends to be smaller than a road or hybrid.

There are standard sizes of wheels, and if you need to change a tyre, its size will be on its side wall just as it is for a car’s tyres. The size is a combination of diameter and width, again exactly like a car. The diameter is for the whole wheel when the tyre is in position.

Some people prefer smaller wheels, some larger. It is all a matter of personal preference plus what the manufacturers recommend with the frame.

Diameters are normally quoted in inches or ISO standard sizes (700c for example which is a 29” / 622mm wheel).

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