Bike Size Calculator | Frame Size Guide

What road bike size do you need?

【?】 Simply enter your inside leg measurement into our calculator and get your road bike/frame size. 

Use this as a rough guide, we work to a 1cm margin either side.

 

 

How To Measure A Bike's Size?

'One size fits all' is as mythological a concept in bicycle frames as it is in any other field or industry. 

If you are familiar with your frame size this page may still be of some use for you. If you have any doubts or are new to buying a bike, read on.

Frame sizing is a notoriously difficult minefield to navigate. There is seemingly conflicting information at every turn and different frame geometries and disciplines to consider. Finding the right size frame can seem a daunting endeavour. This guide is offered to help guide you through this process. It is worth noting that it is just that, a guide. It is by no means definitive and nothing can really compensate for seeing and trying bikes for size in the flesh, but our guide will aim to give you a rough idea of what you should be looking for.

A properly fitting bicycle is imperative for maximum comfort, efficiency and most importantly, enjoyment. Life is too short to ride a heavy, unreliable and ill-fitted steed.

 

The 3 most important measurements to ensure correct sizing 

It is worth familiarising yourself with some basic terms in relation to what is actually being measured on the frame, when it's referred to and how it will in turn affect your position on the bike. 

centre to centre measurement of 80s roberts frame

1 - 'Centre to centre'

The most common measurement used to get an overall idea of the size of a frame is the 'centre to centre' measurement. If you see a frame listed as one number, '54cm', '25 inch' or '60cm' for example, it is most likely referring to this measurement.

If finding the right frame size was as easy as this one measurement, you wouldn't be reading this, or certainly have read this far! There is a reason why Professional Bike Fitting has become big business and is a must for any serious rider.

There are other measurements and factors at play other than simply the 'centre to centre' seat tube measurement. After all, you wouldn't expect a tailor to take one measurement and provide you with a well fitted suit!

We use a simple calculation developed in the 80s by LeMond's Tour winning team, it is simple and best applied to the style and geometry of 90% of the bikes we sell. Pioneered by coach Cyrille Guimard, our calculation is also used by many other bicycle retailers.

standover height diagram for a bicycle frame

2 - 'Standover height'

Much like buying a suit in fact, it starts with an inside leg measurement. Guimard proposed taking your inside leg measurement and multiplying it by 0.67. Round down and this should give you a rough idea of your frame size, use our handy slider to do the maths for you!

This is an important part of the anatomy to consider as it directly affects 'standover height', the next important measurement in our frame sizing guide. 

This is a prospective measurement in an unbuilt frame and easily measured on a completed bike, it corresponds to the height that the top tube of the frame will stand off the ground. If 'standover height' exceeds your inside leg measurement then it will be pretty uncomfortable during mount and dismount and is too big. 

The same bike fitted with different components can have varying 'standover' measurements as there are a few things that can affect this measurement.

Firstly, wheel size makes a bike difference, modern manufacturers of kids bikes tend to use 20" and 24" for younger age groups and 26" wheels for older kids for this very reason. So if you are on the shorter side or have a shorter inside leg measurement then you may consider a 26" inch wheel frame, as standover will be of particular importance.

A bike with 700c 'road' wheels and fatter tyres will have a taller standover measurement than the same bike with the same wheels and slimmer tyres.

top tube lenght chart for a bicycle frame

3 - 'Reach' 

'Top tube length' is simply the length of the tube joining the head tube to the seat tube, the length of which will affect your 'reach'.

Too long and you will be overstretched, especially when braking and the bike won't be much fun to ride. Any long distances would be pretty much be out of the question without accompanying back pain. Too short and you may find you have to overcompensate in other areas, for example, seatposts raised too high, saddles at crazy angles or bars far away from a neutral position are commonplace on ill fitting bikes. These adjustments may seem to rectify the initial problem in the short term, but long term can mean pain and discomfort migrates to other areas of the body as a result. 

Some of these frame measurements can be compensated for with components. As with other frame measurements 'reach' can be adjusted with different length stems. Although nothing is as beneficial as a well fitted frame. 

Not technically a 'standover' fitting issue but not unrelated is that of crank arm length. It roughly correlates to your inside leg measurement, a general rule of thumb is that the shorter the measurement the shorter the crank arm required. 

 

Bike Sizing Chart

Inside Leg Frame C-C
70 - 73 cm 46 – 48 cm
73 – 76 cm 48 – 50 cm
76 – 79 cm 50 – 52 cm
79 – 82 cm 52 – 54 cm
82 – 85 cm 54 – 56 cm
85 – 88 cm 56 – 58 cm
88 – 91 cm 58 – 60 cm
91 – 94 cm 60 – 62 cm
94 – 97 cm 62 – 64 cm
frame size guide diagram
 
It is the aim of this guide to steer you in the right direction and to help you find the right size frame for you. Unfortunately, no guide can be truly definitive. So it is important that when you embark on the mission of buying a new bike that you equip yourself with a basic understanding of how and where measurements are taken and what they relate to in your anatomy.
 
Once equipped with this basic understanding of frame geometry it's time to take your measurements!
 
Get an accurate height and inside leg measurement for yourself and write it down. Have it with you, on a scrap of paper or on your phone. It may help to gather some more information, like arm and torso length.
Know your measurements. Now go out and try some bikes!
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