Around 15-20 million bikes get sold each year, and that number is holding steady. Many of us have cherished memories of going bike riding with our siblings, friends, or parents, or adventuring off on our own!

Keep the memory-making coming—and the first step is knowing what size bike is best for you, and the child in your life, which can sometimes get tricky as bike manufacturers all tend to size their bikes differently.

The only way to make sure you get the right bike for your height and inseam is to do the research, but don’t worry – you’ll find your perfect fit in no time thanks to this bike sizing guide!

How Bikes Are Measured

Adult bikes get sized using the frame. This measurement comes from the center of the bottom bracket to the top of the seat tube and is typically expressed in inches or centimeters.

The size of the bike measurement is usually displayed on the bike and may also include standard sizing characterizations like “small” or “large”.

Kids' bike measurements come from the diameter of the wheels. These measurements get taken in inches. Some common sizes for kids' bikes are 16, 18, and 20 inches and go to 24 inches.

Let's get into the different factors that will help you find the right size bike.

How To Measure Yourself For A Bike

When measuring yourself for a new bike, you will need two measurements as a starting point for determining your best bike size. One is your inseam, and the other is your height. You can do this yourself, but it is often easier if you have someone to help you take these measurements.

You should wear your cycling shoes when gathering the measurements. You can also do it barefoot. Either way, stay consistent for both measurements.

Height Measurement

Your height is the measurement from the top of your head to the ground. If you wear your cycling shoes for your inseam measurement, make sure you wear them again for your height. You will need a book, tape measure, and an assistant for this measurement.

Stand with your back against the wall and your feet flat on the floor. Have your assistant place the book on top of your head and press it against the wall. Step away and draw a line along the bottom edge of the book.

Measure from the mark to the floor and that is your height.

Inseam Measurement

Your inseam measurement is from the top of your crotch, along the inside of your leg, down to the ground. This measurement tells you how tall your bike needs to be for a comfortable ride. To get this measurement you will need a measuring tape and a book.

Stand against a wall and place your book between your legs as if it was a bike seat. Hold the spine against the wall as you move away. Measure the height from the top of the book, down to the ground to get the correct inseam.

The inseam can affect the size you choose for your bike. For example, knowing your inseam can determine what size bike for a 5’ 2” person versus what size bike for a 5’ 4”. The heights may be similar, but the inseams can differ depending on body shape.

Standover Height Measurement

One last measurement that comes in handy when picking out the perfect bike is your standover height. You’ll want to be able to comfortably stand over your bike while letting your feet touch the ground. Finding your standover height is simple – just add one inch to your inseam measurement. From there, you can compare it to the bike size chart to find your perfect bike size.

Choosing Your Style and What Size Bike

Bikes come in many different styles and each will affect the sizing. Mountain bikes, road bikes and hybrid bikes are the three main categories. Each of the types of bikes has its own size chart based on your inseam (standover height) and height.

The size you choose can have a big impact on how comfortable you feel when you ride the bike. Ill-fitting bikes can cause pain and injury if not dealt with.

Mountain Bikes

Mountain bike frames get sized in inches. You may also find measurements like S and L alongside the numerical measurement. This measurement gets taken from the center of the bottom bracket to the top of the seat tube.

Mountain bikes provide more standover height with a downward slope in the top tube.

Road Bikes

You will most often see road bikes sized in centimeters. Most road bike manufacturers will also provide a rough size such as small, medium, or large along with the numerical measurement. The common measurement is from the center of the bottom bracket to the top of the seat tube.

Manufacturers may also give the measurement from the center of the bottom bracket to the middle or top of the top tube. Each manufacturer is different, so be sure to check with each individually.

Hybrid or City Bikes

Hybrid bikes combine the features of a road and mountain bike. These are sized in either inches or centimeters. They are also often sized using rough sizes (x-small, medium, etc.) to give buyers a better idea of the size they need.

The frame size gets measured from the top of the seat tube to the center of the bottom bracket. Again, each manufacturer is different, so check with yours to confirm sizing.

E-Bikes

Though e-bikes get made differently than typical bikes, they get measured in much the same way. They are sized the same as road bikes, in centimeters, along with rough sizes like S, M, and L. Since e-bikes are expensive, you may want to do a trial ride before purchasing.

Kids Bikes

Bike shopping is exciting – especially when it’s your first! Before you buy a bike for a kid, you will need their age, height, and inseam to determine the correct bike size that will best fit your child. Kids' bikes are measured using the wheel diameter instead of the frame as in adult bikes. If you mix the two up, you may end up with the wrong size bike!

Kids' bikes come in a variety of sizes ranging from 12 inches to 24 inches and typically offer a suggested age range as well as developmentally appropriate features. (For example, certain models of Retrospec Kids’ Bikes offer hand brakes and coaster brakes so older kids can get a feel for both.) The wheel size increases by 2 from 12-20 inches and then goes up to 24 inches. After your child outgrows a 24-inch bike, they will need an adult bike. 

Compare their measurements to a kids’ bike size chart to find their perfect fit. If your child isn’t ready for pedal bikes yet, consider getting them a balance bike to help with their coordination.

Get Ready to Ride

Now that you know how to find what size bike you need, you are ready to hit the road (or trail) on two wheels. Knowing your height and inseam are crucial to finding what size bike for kids and adults you need. Having a bike that fits you will make every ride more enjoyable. If you still have questions or are unsure, look for a bike size calculator online or visit a local bike dealer for a test ride in order to help make your decision.

If you are looking for a new set of wheels, check out our selection of bikes. We have everything from city bikes to beach cruisers! Find your perfect match today!