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How to Find the Right Size Road Bike

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Road bikes are a fast kind of bike that can really let you eat up the miles on the roads. Check out this guide to find the right size for you.

How to Find the Right Size Road Bike

Whether you plan on churning out miles by the hundred or just riding to the shops and back, having the right size road bike really helps you to be comfortable and in control. This handy guide will show you how to measure yourself and what to look for, so that you can buy with confidence.

What do the numbers mean?

Bikes come in many different sizes, normally a couple of centimetres apart. These measurements in centimetres normally refer to either the top tube or the seat tube. On some modern bikes, they're more of a guide to how big the bike is compared to others, rather than a specific part of the bike.

So where do I start?

The simplest way of finding the rough size of bike that you might need is to measure your height and compare this to the tables that are included on each bike's product page.

If you'd like to be a bit more certain, take your inseam measurement and compare this to the table as well. You can measure your inseam by placing a book between your legs as high as is comfortable and then getting someone to measure from the top of the book to the floor using a tape measure.

I'm still not sure!

If you're still not quite sure (or you're on the border between sizes) you should think about how long your reach is compared to your height. As bikes get bigger, they also get longer, meaning that the handlebars will be further away on a bigger bike. Someone with a longer reach might be more comfortable on a longer bike, and someone with a shorter reach might be better on a shorter bike.

To find out how your reach compares to your size, measure your ape index. Here's how to do it:

  • Use a tape measure to measure your height and your arm span.
  • Then, subtract your height from your arm span
  • If you get a positive number then your reach is relatively long for your height. If you get a negative number then your reach is shorter.

So, for example, if your height is 5 foot 8" and your arm span is 5 foot 10". Subtracting 5 foot 10" from 5 foot 8" gives you 2. 2 is a positive number, so you might be better off on a bigger size if you're struggling to choose between two sizes.

How do I know if a bike is the right size for me?

Road bikes fit differently depending on what they're meant to be used for. A racing bike might have you bending over and reaching forwards for the handlebars, while a sportive or endurance bike might have a shorter and more upright position. However, a bike that fits properly will let you:

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

Still not confident?

Remember, modern road bikes are very adjustable. The saddle moves up and down, as well as forwards and backwards. The handlebars can be raised or lowered, and the stem can be swapped for one of a different length. If you fall between two sizes, it normally means that either one can be adjusted for your preferred fit. This is why you often see an overlap between the sizes we recommend.

And there you have it! We hope this guide has helped to give you an idea of how to tell what size bike you need. If you're looking to find the right size for a different kind of bike, head over to our guide to be pointed in the right direction.

Ready to decide? Head over to our range of road bikes!

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