What size bike do I need?

If you’re in the market for a new bike, knowing what size bike you need will probably help you narrow down your search. After all, bikes come in all shapes and sizes, and the right one for you depends on your body type, cycling uses and personal preference.

In this article, we’ll help you figure out how to choose a bike that’s the perfect size for you, but it may help you to know which bike you’re looking for before you dive into sizing guides. Head over to our bike buyers guide to help you make this decision, or choose your bike from the following list for more in-depth help with bike sizing:

Depending on the type of bike you’re looking to buy will change how you need to measure yourself or someone else for a bike. We have a range of guides below to help you find the perfect mountain bike, road bike or a new E-bike.

Otherwise, let’s take a look at the key elements of bike sizing that you need to be aware of.

How to measure for a bike

Properly measuring for a bike is incredibly important and being comfortable matters to both professional and casual cyclists alike.

The key elements to be aware of are:

  • Your height
  • The length of your inside leg
  • The frame size of your chosen bike

Knowing these three measurements will enable you to choose a bike that’s roughly the right fit for you. The frame of your bike is one of the only elements that can’t be changed; after all, you can raise or lower handlebars and seats, so getting this right really matters.

Similar to how shoe sizes aren’t always universal, different frame sizes listed by different manufacturers may not be completely accurate so be sure to check your manufacturer's own size guide before making an online purchase.

To help, we’ve created a bike size chart which should make finding your ideal frame size a little bit easier.

Bike Frame Size Guide

Below is a typical bike size guide to help get you started.

Please note that this is a general chart and, as previously mentioned, bike sizing will differ from bike to bike and between bike types. We, therefore, recommend always referring to the specific size guide provided on the product page for your chosen bike.

Height (Centimetres & Feet) Inside Leg Road Bike Frame Size (CM) Mountain Bike Frame Size(CM)
152cm / 5'.0" 71cm / 28" 48cm (XX Small) 15" (X Small)
160cm / 5'.3" 75cm / 29.5" 51cm (Small) 16" (Small)
170cm / 5'.7" 79cm / 31" 54cm (Medium) 17" (Medium)
175cm / 5'.9" 83cm / 32.5" 56cm (Large) 18" (Medium)
180cm / 5'.11" 85cm / 33.5" 57cm (X Large) 19" (Large)
188cm / 6'.2"  89cm / 35" 60cm (XX Large) 20" (Large)
196cm / 6'.5" 93cm / 36.5" 63cm (XXX Large) 21" (X Large)


What size frame do I need if I'm in between sizes?

You might find that the results you’re getting from bike sizing charts or our bike size calculator seem a little inconclusive and you’re being offered two different frame sizes.

What this means is that you’re effectively between sizes, and both the larger and smaller frames would be suitable.

So how do I narrow it down to find the best sized frame for me?

Well, the key measurement is ‘reach’. This is basically how long the bike feels when you’re in the riding position. Your reach is influenced by your upper body length (also known as your ‘trunk length or sitting height).

If your trunk length is longer than average, then we’d recommend the larger of the two sizes that you’ve been given. If your trunk length is shorter than average, then go for the smaller of the two sizes instead.

If you’re still unsure what size bike frame is right for you or need a helping hand, then nothing beats trying the bike out in person. Simply pop into your local Halfords store and we’ll be happy to help find you the right size bike for your next journey!

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