specialized giant cube cannondale merida castelli endura altura
A mountain biker riding a Merida electric hardtail mountain bike through an overgrown trail

Bike Size

What size bike do I need?

Below you'll find our typical bike sizing chart. Click on the frame size you want to see the bike models that are right for you.

Height (feet & inches)

Height (cm)

Frame Size (inches)

Frame Size (cm)

General Sizing

4’8” – 5’1”

143 – 155cm




5’1” – 5’4”

155 – 163cm




5’4” – 5’7”

163 – 170cm




5’7” – 5’10”

170 – 178cm




5’10” – 6’0”

178 – 183cm




6’0” – 6’3”

183 – 191cm




6’3” – 6’5”

191 – 196cm




6’5” – 6’9”

196 – 205cm




You can also check specific bike size tables for bike you want on its product page. Alternatively, go to the brand specific bike sizing charts for the model that you are interested in.

Can I use the typical bike size chart for women’s specific bikes?

Yes, typically women’s specific bikes have different bike frame sizes to unisex bikes, but they are sized in the same way.

Women tend to have shorter upper bodies than men, so the women’s specific frames are shaped differently. The top tubes are slightly shorter than unisex bikes which reduces reach, so female cyclists won’t feel so stretched out. As this doesn’t affect the seat tube length (saddle height) or stand-over clearance, our bike size calculator is suitable for all types of bikes.

Women who are between sizes on a Unisex bike may choose the smaller of the two recommended sizes. See the what if I am between sizes section for more on this.

Woman cycling on a Liv road bike

What size frame do I need if I am in-between sizes?

Sometimes bike sizing charts or our bike size calculator will recommend two different bike frame sizing options. This means that both the larger and smaller road bike frame size or mountain bike frame size recommended will be suitable for you. To help you make the right choice we asked a bike specialist Dr. Barney Wainwright for some advice.

The key measurement is reach which is how long the bike feels in the riding position. Reach is affected by your trunk length as well as the length of your arms. Trunk length, also known as upper body length or sitting height, is the measurement from your hips to your shoulders.

If your trunk length or sitting height is longer than average, then the larger of the two sizes recommended in the size chart will be ideal.

If on the other hand you have a shorter than average trunk height, then the smaller of the two recommended sizes will probably be best for you.

Once you have your bike there are some adjustments that you can make to fine-tune the fit. Have a look at the other videos in our Boardman Performance Centre bike sizing series in our Bike Fitting Guide to see how easy it is to get the right bike fit.

Do sizes vary for different types of bikes?

Road bike sizing and mountain bike sizes are slightly different and the units used in bike sizes vary depending on type and brand. Road bike sizes are usually given in centimetres, while mountain bike frame sizes are quoted in inches. Fortunately, our bike size chart takes away the guesswork as it suggests mountain bike frame size and road bike frame size in either inches or centimetres alongside manufacturers bike size charts.

Many bike manufacturers will quote bike sizes as S, M, L or small, medium or large etc. on some or all their models. Kids bike sizes are usually based on wheel size. Some MTB sizing guides will use inches while you might find road bike sizes  in centimetres.

Mountain bike and road bike sizing

For model specific sizing please check the Sizing Tab on the product page of the bike that you are interested in.

Please note all sizing information is to be used as a guide only. This is because bike sizes can vary for different brands and models. If you are unsure which size bike will be best for you, our bike specialist team are here to help. Call us on 01792 346501, chat with Live Help or email info@tredz.co.uk and we will be happy to assist you.

Brand specific size guides

The above information is a general overview to bike sizing, model specific sizing can be found on all the product pages for the most popular brands, if in doubt use these tables for the most specific sizing information.

Bike Geometry

Discover what the numbers mean

MTB Geometry Guide

MTB Geometry Explained

Mountain bike geometry can be confusing. Here we explain the most important metrics and what they mean. 

Road Bike Geometry

Road Bike Geometry Explained

Here we explain the most important geometry numbers, what they are and what they mean.