Discover How You Measure Bike Size Charts & Photos Included

You’ve decided that you want to buy a bike online because the nearest bike store is an hour away and has a limited selection of bikes. You look online and find that bikes come all in sizes and shapes and types.

What are you going to do?

That’s where this article will help you to make a better informed decision about what size of bike is a better fit for you.

What is the right bike size for me?

This seems like a very simple question, right? If only that were the truth! Lucky for you, we’ll break the answer down so we can better define the real question, what is the right road/mountain/triathlon/bmx bike frame size for my body?

Regardless of what type of style of bike we are looking to buy, we first need to measure our body so we can match it to the bike frame size that goes with the type of bike we are going to purchase.

How do you measure your body to fit the bike?

Grab a medium size hard cover book, a single DVD case, a tape measure, and a friend. If you are by yourself, that’s okay because I’ll show that you how to do it on your own.

  1. Put on the shoes that you will wear when you ride.
  2. Grab the hard cover book, DVD case, and tape measure and meet me in the hallway.
  3. Put the hard cover book between your legs, spine up into your groin (kinda like riding a bike, huh).
  4. Back up against the wall with your feet about 6 inches (15 cm) apart, placing the DVD case between your feet.
  5. Extend the tape measure from the top of the spine of the book to the floor.
  6. Read the measurement (mine is 31 1/2″ / 80 cm), this is your inseam length. Remember, to get centimeters from inches multiply the number of inches X 2.54. For example, 31.5″ X 2.54 = 80.01 or 80 cm.

If you are lucky enough to live by a large bike store, you could always go in and have them measure you but then you might feel obligated to buy one of their bikes and they may not have the bike that you want. Totally up to you.

Another measurement that is good to have is your height while wearing your riding shoes. Depending on the type of bike that you buy it could help with finding the best fit for you.

Now, if you want to go all out and get every measurement imaginable for fitting you to a bike, then you are definitely going to need someone to help you out with getting these measurements.

  1. Inseam Length – Covered Above
  2. Sternal Notch Height – Standing upright against a door or wall, measure from the floor to your sternal notch. For me that’s almost 52″. Now take that measurement – inseam length = sternal notch height. For example, 52″ – 31.5″ = 20.5″ or 52 cm (52.07). 
  3. Lower Leg Length – Sit down so that your lower legs are at a 90 degree angle from your upper legs. Feel your knee from the outside of your leg and just below it you will feel a bone sticking out, this is your styloid process. You’ll either need to mark this spot or keep that you finger there while you stand up because it will magically disappear when you stand up to measure the distance to the floor. Mine is 19.5″ or 49.5 cm. The height does change slightly when you stand up. 
  4. Foot Length – Stand up against the door with your feet parallel to each other. Place the spine of the hard cover book up against your toes and carefully step away from the door. Now measure from the wall to the book spine and you have your foot length. Mine is 11″ or 28 cm. The toes on my right foot got messed up in a motorcycle accident, so I’m taking the longest measurement from my left foot. You’ll see what I mean in the photo. 
  5. Arm Length – Make a fist around a pen and hold your arm straight out from your side. Measure from your rib cage to the front body side of the pen. Do this for both sides and average the number. For example, if mine were 24 and 25 inches the average would be 24 + 25 / 2 or 49 / 2 or 24.5″ (62.23 cm). 
  6. Shoulder Width – Measure the distance between the acromiom processes across your back. You can feel this bone sitting above your shoulder. This measurement is important for recommended handlebar width on road bikes. 

Now You Match Up Your Inseam and Height to the Road Bike Size

We will start from shortest to tallest with road bikes, mountain bikes and kids’ bikes (source: Amazon’s Bike Fit Guide):

Road Bike Size Chart

Mountain Bike Size Chart
Kids' Bike Size Chart

Remember, ladies and gentlemen, if you have a question about anything discussed in “Discover How You Measure Bike Size”, please let me know in the comments below and I can always add more information to this article.

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