Posted in Cycle

Finding the right size of bike frame for you

Buying the correctly sized frame for a road or mountain bike is vital not just for maximising your performance and enjoyment, but also to reduce the chance of picking up an injury.

You might think buying a bike online makes it harder to get the right size of bike frame, but it's much easier than you might think, enabling you to take advantage of the low prices found online. 

This guide will help you gather the measurements you need to pick the right frame for you, no matter your cycling discipline, and which bicycle measurements are the most important for perfectly matching with your dimensions. 

Why bike size is so important

Because of the continuous and repeated movement used to drive the pedals, any excessive strain or muscle pulling quickly becomes problematic as it's repeated thousands of times on even the most moderate ride. 

The health benefits of cycling are beyond question and cyclists are among the fittest people on the planet. That's why bike size is of such fundamental importance; get it wrong and you could undo all the amazing benefits the sport has to offer. 

The size of your bike will dictate your cycling posture, and whether or not you can efficiently and safely ride it.

But there is a 'Goldilocks' size for every rider. Get a frame that's too small and you could suffer an injury on long rides from holding a cramped position; clip the front wheel with your toe while turning; and be unable to deliver your full range of movement, limiting the power you can push with. If you're bike is too big, you'll not be able to deliver your power efficiently, or handle the bike properly. 

There are many different types of bikes, from classic road bikes, cyclocross, mountain bikes, commuter bikes, and many more. Each of them have a different riding position tailored for their purpose - a road bike, for example, will be designed for a lower riding posture for speed and power, while a sportive or endurance bike might have a shorter and more upright position to help stability and control. 

In essence, a bike that fits properly will let you:

  • Stand over the top tube with around two inches of clearance
  • Pedal with a slight bend in your knee at the bottom of the stroke
  • Reach the handlebars and brake levers comfortably

This Wiggle bike size guide makes it easy to pick the right size of bike for you, and explains how to use the specific size charts on each bike product page. You will also find geometry charts on the product pages for bikes sold at Wiggle, which you can use to match your height and reach to find a perfect fit.

If, after reading this guide, you're still not sure which size you need, you can book an appointment to talk to a Wiggle expert using our call-back service to discuss sizes and anything else you may like to know.

Once you have provisionally chosen your bike size, the Wiggle qualified team of mechanics will still individually check each order against measurements supplied by you to ensure the size chosen is correct.

All this should provide you with unrivalled confidence for buying a bike from Wiggle. Once you receive the bike by post, you simply follow a few quick assembly steps. Watch the video below to see how easy it is to unpack your new bike. 


How do I choose the right size bike?

Bikes are generally measured and defined by the length of the seat tube - this is the tube on the bike that the seat post (and saddle) slide into.

Traditionally, this measurement is given in metric (cm) for road bikes, and imperial (inches) for mountain bikes; however, some bikes are also sized as small, medium, large etc.

The way manufacturers measure their bikes can differ slightly from one brand to the next. This is why Wiggle measures all of its bikes in the same way and provides these universal measurement standards on its product pages for bikes.

bike size guide wiggle



What measurements do you need?

There are three measurements that will assist you in choosing the right size bike for your body shape: your height, your inside leg measurement, and your reach.

Standover height

Your inside leg measurement will determine your standover height - this is the clearance between the top tube of the bike and your crotch when stood just in front of the saddle. We suggest a clearance of at least two inches to enable you to hop off quickly as and when required. 

bike size guide wiggle


If your height and inside leg measurements put you in-between two sizes, then your upper body should be the deciding factor in selecting the best-sized bike for you. Your upper body dimensions determine your reach, and this affects how 'stretched-out' you'll be along the top tube of your bike. To work out if you have a long or short reach, you need to determine your 'Ape Index' (arm span minus height).

  • If you have a positive Ape Index (i.e. your arm span is greater than your height), then we suggest you go for the larger of the two bike sizes.
  • If you have a negative Ape Index (i.e. your height is greater than your arm span), then you will probably be more comfortable on the smaller of the two bike sizes.

Example: 152cm (arm span) - 163cm (height) = minus 11. In this example, you have a negative 'Ape Index', and should go for a smaller frame size.

bike size guide wiggle

If you find your reach is a little short, you may be tempted to pick up a longer stem - the short horizontal bar to which your handlebars are attached. In certain circumstances, this can be a good way to lengthen your ride position, but be aware that it can also negatively impact the bike's handling. The best solution is to ensure your bike fits from day one.  

Once you've found the right size, you can make adjustments to the fore and aft position of your saddle and its tilt, the angle of your handlebars, and the distance to the brake levers to get the perfect position.  

Women-specific bikes and unisex bikes

On average, women have longer legs and shorter torsos than men of the same height, so female specific bikes have a shorter top tube with narrower handlebars and female specific saddles.

However, people are not 'average' and a bike should be the perfect fit for you individually, whether it is a unisex bike or a women's specific fit.

As a general rule, if you are shorter than about 5ft 5 (165 cm) or you have felt too stretched on a men's or unisex bike before, then you may be more suited to a female specific bike that offers smaller frame sizes.

If in doubt, feel free to book an appointment with one of our experts who can call you back to help find the right bike for you.

View our range of Women's Specific Bikes at Wiggle


How do you choose the correct size kid's bike?

Children's bikes are measured and sized in a different way from adult bikes. They are usually categorised in age ranges and wheel sizes.

Below are some key points to keep in mind when sizing a bike for your child:

  • Don't rely completely on an age range to size a bike for your child as this is only for guidance. If your child is tall for their age, then you may need the next size up.
  • Height and inside leg measurement is still the key factor when sizing. Keep this in mind when picking your children's bike.
  • It is common to look for a bike that a child will grow into, but this isn't always a good option. If the bike is too big for your child, it will be difficult for them to ride with stability and confidence. Reduce the chance of them falling over and give them the opportunity to learn to ride with skill and passion by getting a bike that fits. 
  • You can always contact us, if you need help!

View our great range of Kid's Bikes at Wiggle


Bike sizing charts

For reference, here are the generic bike size charts for the range of bikes sold at Wiggle.

Click on the bike size guide to take you to the relevant range of bikes.

mountain bikes at wiggle

hybrid commuter urban bikes at wiggle

road bikes at wiggle

road bikes at wiggle

child kids bikes at wiggle