Calculate your frame size

Using our handy frame size calculator you will be able to accurately measure your perfect frame size! With this tool you can say goodbye to an uncomfortable ride, no matter what type of bike you are riding.

To measure the bicycle frame you need to measure the seat tube, which is the distance from the centre of the crank arms to where the seat post comes out of the bike. Confused? Take a look at this photo:

Bike with frame size highlight

To measure the seat tube you will need a tape measure, although some manufacturers will have a sticker with the frame size on the bike! Brands like Gazelle or Batavus are some of the brands that are kind enough to save you searching for that pesky tape measure.

Frame size is a key indicator for almost all bike types. However, BMX, folding and kids bikes are exceptions to this rule as wheel size is a more important determinant of size or even just comfort and handling.

The right frame size is important whatever riding you're doing, from trekking across Europe to pootling down to do your groceries; for the beginner to the hardcore racer. Therefore, we really encourage you to find your right frame size for 3 main reasons: to prevent injuries, maximise efficiency, stay comfortable. Ultimately, this means having more fun on the bike!

Having the wrong frame size can cause injury, most commonly to the back, knees and also wrists. Your lower back especially can overstretch and cause discomfort if you have a frame that is too big, with a telltale sign of this being that your elbows are locked when reaching for the handlebars. Knees are also vulnerable if the frame size is wrong, either being hyperextended at the bottom of the pedal stroke or too bent. Both can cause stress in the tendons and ligaments in your knee, risking injury. Another common injury is wrist pain and is caused when there is unnecessary weight being put through your risks if you’re hunched too much over a small frame.

The right frame size ensures that each pedal stroke will be smooth and optimise the power transfer from your legs through the pedals. Moreover, it also means that you will be comfortable enough to cycle for a longer period of time without feeling aches and pains that will arise from the wrong frame size. Finally, and especially important for road cycling, the right frame size will create the optimal position for you aerodynamics in combination with your pedal stroke - so you will be as low as possible but able to pedal comfortably too!

Having a bike that fits removes many physiological problems that can be caused by cycling. Of course, optimising the contact points with the bike will also make cycling become more comfortable. Having a comfortable saddle, shoes (with the right setup for the clip in pedals if applicable) and gel handlebar or gloves will make your bike feel even more pleasant. However, the right frame size forms the foundation of a comfortable ride and so not having this makes all these additions you can make redundant. With a perfectly fitting frame you should feel relaxed and can more easily train your body to deal with longer rides and more time in the saddle!

Road bikes put the rider in a more aggressive position than other types of bike as aerodynamics is more important - above 14kph, drag from wind resistance and the road surface are your biggest enemies. However, what use is being really aerodynamic if you can only ride 5 kilometres before your back starts aching and you need a crutches once you get off the bike? This is why frame size is so important in finding the balance between speed and comfort.

Our tool can give you an accurate guide to finding the right size for your next road bike, or even to check if your current one is the right fit for you! Using our calculator you will get a small range of sizes to pick from. Even though the difference is only a couple of centimetres it can still make a big difference. If you want a lower, more aggressive position on the road bike then look at the lower frame sizes in the range, and the opposite if you want a slightly more upright fit.

Getting the right frame size for mountain bikes is crucial for managing speed and control on winding, off-road terrain. Most mountain bikes will run smaller frame sizes compared to other types of bikes (road and city bikes for example) and you can see this as mountain bike frames often have a much more slanted top tube. A slanted top tube is important for mountain biking because you can get more clearance when standing over the mountain bike frame, which is important in keeping your undercarriage intact in the event of a crash (which tends to be more frequent than other cycling disciplines)! Also, a smaller seat tube length means you can run a longer dropper seat post, allowing more control on descents. Finally, it makes it easier to accommodate rear suspension on full-suspension bikes.

Our frame calculator will give you a recommended frame size for mountain bikes in both centimetres and inches, to get you the perfect bike to take you on your next adventure and make handling trails and technical descents as easy as possible while being injury free!

So an urban myth is that bicycles - the frame in particular - need to be gendered. If there is a man and a woman who are the same height and have the same inseam then they should get the same frame size - it's that simple! However, as the average height of a woman is smaller than a man, manufacturers tend to market a smaller range of sizes (e.g. an XXS to an M frame) compared to men who will more likely be looking at an S to XXL frame size. But that's not to say that anyone can't look outside this range! What may differ are the components and finishing kits on bikes, for example some bikes may come with a women's-specific saddle.

The best piece of advice is definitely: go to a professional bike fitter. They can accurately measure your physiology and determine what needs to be changed on your bike. On road and mountain bikes this can include adjusting the saddle height, as well as fore and aft; adjusting the stem height and length or even swap the cranks for different sizes. If problems do persist then it could be worth visiting your doctor of physio to see if there is an underlying problem causing this discomfort.

You can do a rudimentary bike fit using online resources such as YouTube and then recording yourself on a stationary trainer or have someone record you as you're cycling. This is really useful to see any irregularities on the bike, but a bike fitter has all the resources to simplify this process while extracting precise data.

Wheel size is more important for some types of bikes than others. Kids, mountain, folding and BMX bikes often have different wheel sizes that can affect performance or just sizing. 

For BMX bikes, 20" is the standard wheel size, with 16" wheels are considered a kids size and 18" preferred for smaller freestyle bikes. Frame size does still make a difference though! Folding bikes generally come with 16 or 20" wheels, with the former allowing for a more compact bike when folded up although this is at the expense of the overall ride quality (speed, comfort and handling are worse with smaller tyres - plus the maximum tyre clearance is lower too).

Mountain bike wheels are a bit more complicated. Adult sizes can come with 26", 27.5" or 29" wheels. There are pros and cons to all sizes. The largest wheels - 29" - give better control off-road and provide the smoothest ride but due to their size are heavier and some might consider them less suited for more technical sections. On the other hand, 26" wheels can be lighter and more agile but can struggle on the rougher terrain compared to the larger wheels. Usually they will be used on smaller mountain bike frame sizes or for disciplines like dirt jumping. Finally, 27.5" wheels represents a compromise between the two other sizes, being neither the lightest or smoothest.

City bikes and road bikes come with 28" wheels as standard, but that's not to say that it's always the right choice. 26" wheels are often a better choice for shorter people or smaller frames because the wheels are more in proportion to the rest of the bike, resulting in better handling. Just because it's bigger or more popular doesn't mean that 28" wheels are always right!

So, here you have the low down on frame sizing. Now let’s find the perfect sized bike for you here.

• If you want to read our ultimate guide to frame sizes click here
• For more help on choosing a second-hand bike click here