How to Size a Bike without Technical Knowledge

Are you planning to buy a Bike? Do you want to know how to size a bike? Do you know you don’t need to have an in-depth technical knowledge to size a bike? The bike size is important to get the best of it. You just need to know some simple things to get the right size for your new bike. I was like you, wondering how to size my bike, and I got tired of the so called experts who just want to sell you gear and upgrades you don’t need. They were giving me contradictory information, even erroneous. I did some research, and now I want to share my research with you.

All you’ll need to Size your Bike

Before we get started, you will need some things to go through this tutorial. They all are simple things you can get at home. This is the list:

  1. Measuring device. It can be a ruler, or measuring tape.
  2. Pen and paper. It is ok if you get a pencil instead.

Make sure you have everything at hand when you proceed to step 1.

STEP 1. Gather Information

There are two basic measures you need to get from your body:

  • Height. There is not much to explain about height.
  • Inseam. Also called the Inside Leg, is the measure from your feet to your crotch. If you have doubts, check this picture:

Via Balancebikeoutlet

Other information you will need is:

  • Gender. Who is using the bike, a man or a woman?
  • Arm Span. The distance you get starting at your fingertip up to your other fingertip, while you are holding your arms straight to your sides. You will need this information only if you are in the middle of two sizes.
  • Age. Only for kids bicycles.

STEP 2. Choose which type of bike are you going to get

The right bike for you is closely related to what are you expecting to do with it. Here are the uses of the different type of bikes to help you make up your mind:

  • Road Bike. A racing bike is characterized by being light and stiff to increase efficiency.
  • Mountain Bike. Also called all-terrain because it is meant to be used in rough terrains.
  • Hybrid Bike. It is a combination of a road and a mountain bikes, suitable for most road conditions and beginners.
  • BMX Bike. The BMX bike is mostly used for acrobatics.
  • Bike for Kids. This sort of bike is mostly for recreational porpoises and should allow the child to grow up.

STEP 3. Calculate your bike size

Once you know what type of bike are you going to choose, it is time to size your bike. Consult the right chart for the kind of bike you are looking for. According to your height and inseam

Chart to calculate your bike size for a Road Bike

Chart to calculate your bike size for a Mountain Bike

Chart to calculate your bike size for a Hybrid Bike

Chart to calculate your bike size for a BMX

To size a BMX bike for acrobatics, you will only need to determine the top tube length according to your height. Everything else is more or less standard. However, it is common that each rider makes further improvements to their bikes according to the use they are giving it. The kind of improvements will come with experience.

bike size for a Hybrid Bike


Chart to calculate your bike size for a Kids Bikes

bike sizes kids

Via bikebarn

For kids, the size of a bike is tricky. You have to be aware if your child’s height is average or if he is under or over the average height. When you get in the middle of two sizes, just choose the bigger one, since most likely the kid will grow up soon, and you want the bike to last longer. Learn more to choose the best bike for your children at the following video:

A Shortcut for all Bikes

Steps 2 and 3 can be done easier if you use an online resource where you just have to choose from drop lists the options. It is available for road bikes, mountain bikes, BMX bikes and bikes for kids. Check it out at:

TEP 4. What to do when you get caught in the middle of standard sizes

If you get trapped in the midst of 2 standard sizes, there is no need to worry. It doesn't mean there is any right bike for you. There are two sizes you can fit. There are various ways to compensate it:

  • You can move the saddle down, up, forward or backward to make you feel comfortable.
  • To move the handlebar up or down is another adjustment you can do. You will require a tool for most models, but it is possible.

Other things you can do are to take a decision based on your arm’s length. Use your notes and subtract your arm span from your height. If the number is positive, then go for the bigger bike. If the number is negative, go for the smaller.


Was this tutorial on how to Size a Bike without Technical Knowledge what you expected? To know in advance which size you need your bike is important to get rid of sellers who just want to make their quote but are not helping. If you enjoyed this guide, share it with others like you and me to spread the knowledge, and tell us about your experience in the comment section.

Remember that you can save some time by using the automatic tool at:

About the author

    Maureen Sledge

    I’m Maureen, and I’m absolutely in love with cycling blogs. I’m a cyclist at heart but being the mother of one small boys, it’s not always easy to keep up with fancy cycling… so I rely on the support of other blogging cyclists like me to help along the way.