I get it! You’re looking to buy a new bike and aren’t sure which bike size you need.
I also understand that bike size charts can be confusing and hard to follow, so I’ve put together this simple bike size guide for you.
A well-fitting bike is not only more comfortable, but will also allow you to perform to the best of your ability without placing unnecessary strain on your body.
This guide contains some of the most accurate bike size charts, including data based on average rider sizes from around the world. So whatever type of bike you’re looking to buy, I’ve got you covered!
If you’re buying a new e-bike, check out our up to date e-bike size charts. Or, if you’re shopping for a new mountain bike, I’ve put together one of the most accurate mountain bike size charts used by thousands worldwide, that’ll help you select the most suitable bike size.
Towards the bottom of the article, I also cover the most common bike size FAQs.
“What bike size do I need?” – Let’s find out!
How Bikes Are Measured (How Does Bike Sizing work)
There are two standard ways to determine bike sizing.
For adults, bikes are sized by their frames. The size measurement you see displayed by manufacturers and retailers is the length from the centre of the bottom bracket to the top of the seat tube.
The size of an adult’s bike is typically displayed in inches or centimetres and are often shown alongside a rough size guide such as small or large.
On the other hand, children’s bikes are put into size categories based on the diameter of their wheels. Sizes for children’s bikes are measured in inches.
Common kids bike sizes include 16,18 and 20 inches.
This article will let you know how to choose the perfect bike size for your kid.
Kid’s bike sizes go up to 24 inches, and once a child has outgrown a 24-inch bike, they’re ready to ride an adult-sized bicycle!
The best fit bike frame or wheel size correlates with an individual’s height and inseam. Most bike manufacturers use the same sizing method, but the brand and geometry of a bike can alter its recommended rider size.
Below I’ll teach you the quickest way to measure your inseam and height to find your ideal bike size.
How To Measure For a Bike (How To Size a Bike)
Now that you understand the basics of how adult’s and kid’s bikes are measured, I’ll teach you the easiest way to measure yourself for a bike.
You need to take two measurements to determine the correct bike size for you. These measurements are rider inseam and rider height.
The simple steps below will talk you through the most reliable ways to obtain these measurements.
Both measurements will be easier to take if you have a friend with you to help. However, they can be taken by yourself, so don’t worry if you don’t have an assistant.
I recommend you take these measurements whilst wearing your preferred cycling shoes. If, however, you want to take your measurements with shoes off, that’s fine.
For accuracy, it’s essential to take both measurements, either barefoot or with shoes on, don’t alternate.
How To Measure Inseam For Bike Size
Your inseam is the distance from the top of your crotch, down the inside of your leg, to the ground.
The inseam measurement determines how tall the bike needs to be for a rider to comfortably reach the ground with their feet when seated on the bike.
To obtain your inseam measurement, you’ll need a sturdy book and a measuring tape.
If you’re unsure about taking your inseam measurement, the diagram above will be helpful.
- On flat ground, stand with your usual cycling shoes on and back to a wall, feet spaced shoulder-width apart.
- Take a sturdy book and ask your assistant to place the book as high as comfortable between your legs (mimicking the bike seat). Make sure the book’s spine is pressed flat against the wall.
- Whilst your assistant holds the book firmly in place, step away from the wall taking care not to knock the book.
- Now, take a measuring tape, and measure the distance between the top of the book and the ground.
- This length is your inseam. Please take note of it to avoid having to remeasure.
How to Measure Height For Bike Sizing
Your height is the distance from the floor to the top of your head.
If you wore your regular cycling shoes to take your inseam measurement, wear them again to take your height.
To measure rider height for a bike, you’ll need a sturdy book and a measuring tape. A pencil will also be useful if you’re happy to put a light mark on your wall, which you can then remove.
An assistant will also be necessary for this step to make sure the measurement is accurate.
If you’re not sure how to measure your height, the diagram above will be helpful.
Measure your height for bike sizing with these simple steps:
- If you wore your preferred cycling shoes to measure your inseam length, keep them on, otherwise continue barefoot.
- Stand up straight with your back against a wall, feet shoulder-width apart and chin parallel to the ground.
- If you have an assistant to help, get them to take the book and place it flat on the top of your head whilst pressing it into the wall.
- Now, step away from under the book, making sure it doesn’t move.
- If you’re happy to draw a small line on your wall, take your pencil and lightly draw a 1cm line where the book meets the wall.
- Using a measuring tape, measure the distance from the ground to the line you’ve drawn or to the top of the book.
- This measurement is your height for bike sizing.
Bike Size Charts - Adults Bike Sizes For Every Bike
As you’ll now understand, the size of an adult bike correlates with rider inseam and height measurements.
Below you’ll find bike size charts for the most popular bike types.
Underneath each bike size chart, I explain exactly how the specific bike type is measured for its frame size.
You can also use the buttons below to quickly navigate to your desired bike type size chart.
Road Bike Size Chart
Rider Height | Rider Inseam | Suggested Road Bike Frame Size | |||
---|---|---|---|---|---|
4'10" - 5'2" | 147cm - 157cm | 24” - 29” | 60.9cm - 73.6cm | XX-Small | 33cm - 37cm |
5'2" - 5'6" | 157cm - 167cm | 25” - 30” | 63.5cm - 76.2cm | X-Small | 38cm - 42cm |
5'6" - 5' 10" | 167cm - 177cm | 26” - 31” | 66cm - 78.7cm | Small | 43cm - 47cm |
5'10" - 6'1" | 177cm - 185cm | 27” - 32” | 68.6cm - 81.3 cm | Medium | 48cm - 52cm |
6'1" - 6'4" | 185cm - 193cm | 28” - 33” | 71.1cm - 83.8cm | Large | 53cm - 57cm |
6'4" - 6'6" | 193cm - 198cm | 29” - 34” | 73.6cm - 86.4cm | X-Large | 58cm - 61cm |
Fall in between two size categories, or can’t decide which bike size you need?
How Are Road Bikes Measured?
Road bikes are almost always sized in centimetres.
Often manufacturers will also present a rough size such as medium or large alongside the frame size measurement to further assist potential customers.
Frame size measurements displayed on a road bike typically indicate the distance between the centre of the bottom bracket (centre of the front chainring) up to the top of the seat tube (where the seatpost is inserted).
However, some manufacturers provide a measurement from the centre of the bottom bracket to the middle of the top tube, or from the centre of the bottom bracket to the top of the top tube.
As manufacturers vary the way they size a road bike, so it’s always worth getting in contact or testing a bike if you’re unsure of its sizing!
Mountain Bike Size Chart
Rider Height | Rider Inseam | Suggested Mountain Bike Frame Size | |||
---|---|---|---|---|---|
4'10" - 5'2" | 147cm - 157cm | 24” - 29” | 60.9cm - 73.6cm | XX-Small | 13" - 14" |
5'2" - 5'6" | 157cm - 167cm | 25” - 30” | 63.5cm - 76.2cm | X-Small | 15" - 16" |
5'6" - 5' 10" | 167cm - 177cm | 26” - 31” | 66cm - 78.7cm | Small | 17" - 18" |
5'10" - 6'1" | 177cm - 185cm | 27” - 32” | 68.6cm - 81.3cm | Medium | 19" - 20" |
6'1" - 6'4" | 185cm - 193cm | 28” - 33” | 71.1cm - 83.8cm | Large | 21" - 22" |
6'4" - 6'6" | 193cm - 198cm | 29” - 34” | 73.6cm - 86.4cm | X-Large | 23" - 24" |
Fall in between two size categories, or can’t decide which bike size you need?
How Are Mountain Bikes Measured?
Unlike road bikes, mountain bike frames are sized in inches.
It’s common also to find rough measurements such as small or large alongside the frame measurement. These rough size guides provide additional guidance to consumers.
The frame size of a mountain bike is measured by taking the distance between the middle of the bottom bracket (centre of the front chainring) and the highest point of the seat tube (where the seatpost enters the frame).
The top tube of a mountain bike typically slopes downwards from the head tube to the seat tube to provide more standover height for riders.
However, some manufacturers enjoy making things tricky and can take frame size measurements using slightly differing methods!
So don’t hesitate to get in contact with retailers or manufacturers if you’re not sure which size of a specific bike model you require.
Hybrid/Commuter/City Bike Size Chart
Rider Height | Rider Inseam | Suggested Road Bike Frame Size | |||
---|---|---|---|---|---|
4'10" - 5'2" | 147cm - 157cm | 24” - 29” | 60.9cm - 73.6cm | XX-Small | 33cm - 37cm |
5'2" - 5'6" | 157cm - 167cm | 25” - 30” | 63.5cm - 76.2cm | X-Small | 38cm - 42cm |
5'6" - 5' 10" | 167cm - 177cm | 26” - 31” | 66cm - 78.7cm | Small | 43cm - 47cm |
5'10" - 6'1" | 177cm - 185cm | 27” - 32” | 68.6cm - 81.3 cm | Medium | 48cm - 52cm |
6'1" - 6'4" | 185cm - 193cm | 28” - 33” | 71.1cm - 83.8cm | Large | 53cm - 57cm |
6'4" - 6'6" | 193cm - 198cm | 29” - 34” | 73.6cm - 86.4cm | X-Large | 58cm - 61cm |
Fall in between two size categories, or can’t decide which bike size you need?
How Are Hybrid Bikes Measured?
As hybrid bikes combine the characteristics of a road bike and a mountain bike, the frame size provided can either be in inches or centimetres.
Like other types of bikes, hybrid bikes are also generally supplied with a rough size guide such as x-small or x-large to give cyclists a better idea of which bike size they need.
The frame size of a hybrid bike is measured by taking the distance between the top of the seat tube (where the seatpost inserts) to the centre of the front chainring (centre of the bottom bracket).
As with all bike types, manufacturers can size their hybrid bikes slightly differently from one another, so it’s worth getting in touch with them or your retailer if you have any questions regarding hybrid bike sizes!
Time Trial & Triathlon Bike Size Chart
Rider Height | Suggested TT/Tri Bike Frame Size | ||
---|---|---|---|
4'10" - 5'0" | 148cm - 152cm | XX-Small | 47cm - 48cm |
5'0" - 5'3" | 152cm - 160cm | X-Small | 49cm - 50cm |
5'3" - 5'6" | 160cm - 168cm | Small | 51cm - 53cm |
5'6" - 5'9" | 168cm - 175cm | Medium | 54cm - 55cm |
5'9" - 6'0" | 175cm - 183cm | Large | 56cm - 58cm |
6'0" - 6'3" | 183cm - 191cm | X-Large | 58cm - 60cm |
6'3" - 6'6" | 191cm - 198cm | XX-Large | 61cm - 63cm |
Fall in between two size categories, or Can’t decide which bike size you need?
How Are Time Trial & Trialthlon Bikes Measured?
Whilst time trial and triathlon bikes use frames much chunkier than your standard road bike, they’re measured and sized in the same way.
The size displayed on a time trial or triathlon bike is generally given in centimetres and will often be accompanied by a rough size guide such as medium or large.
The measurement displayed represents the distance between the centre of the bottom bracket (middle of the front chainring) and the top of the seatpost (where the seatpost enters the top of the frame).
On the other hand, some time trial and triathlon frame sizes are calculated by measuring from the centre of the bottom bracket to the middle or top of the top tube.
Each method will provide a completely different answer, so if you’re unsure of how a specific brand or model of bike has been sized, it may be worth getting a trial ride before committing to purchase.
BMX Bike Size Chart
Rider Height | Suggested BMX Bike Frame Size | ||
---|---|---|---|
<4' | <122cm | Micro-Mini | 15" - 16" |
4' - 4'6" | 122cm - 142cm | Mini | 16" - 17" |
4'4"- 4'10" | 137cm - 149cm | Junior | 17" - 18.5" |
4'8" - 5'4" | 147cm - 163cm | Expert | 18.5" - 19.5" |
5'4" - 5'10" | 163cm - 181cm | Pro | 20" - 20.5" |
>5'10" | >181cm | Pro-XL & Pro-XXL | >20.5" |
Fall in between two size categories, or can’t decide which bike size you need?
How Are BMX Bikes Measured?
Whilst most types of bikes are sized based upon the length of their seat tube, the size of a BMX refers to the diameter of the bike’s wheels.
Other BMX manufacturers will also provide sizing, which represents the length of the top tube.
Unlike other bike types, BMX bikes don’t tend to use size identifiers such as small or medium and instead have unique sizes such as micro-mini (15″-16″) and expert (18.5″-19.5″).
If you’re not sure which size of BMX suits you best after using our BMX size chart, it may be worth test riding a bike in store.
Electric Bike Size Guide & Charts
Electric bikes have been causing some confusion with cyclists.
Most electric bikes have slightly different frame geometry to conventional bicycles to compensate and make room for their batteries.
This differing geometry has led some cyclists to believe an electric bike’s frame size is measured differently.
Fortunately for all of us, e-bikes tend to be measured in the same way as their non-motorized counterparts.
That being said, the two e-bike size charts below will provide reliable & accurate sizing, helping you to choose the perfect size e-bike.
Electric Road Bike Size Chart
Rider Height | Rider Inseam | Suggested Road Bike Frame Size | |||
---|---|---|---|---|---|
4'10" - 5'2" | 147cm - 157cm | 24” - 29” | 60.9cm - 73.6cm | XX-Small | 33cm - 37cm |
5'2" - 5'6" | 157cm - 167cm | 25” - 30” | 63.5cm - 76.2cm | X-Small | 38cm - 42cm |
5'6" - 5' 10" | 167cm - 177cm | 26” - 31” | 66cm - 78.7cm | Small | 43cm - 47cm |
5'10" - 6'1" | 177cm - 185cm | 27” - 32” | 68.6cm - 81.3 cm | Medium | 48cm - 52cm |
6'1" - 6'4" | 185cm - 193cm | 28” - 33” | 71.1cm - 83.8cm | Large | 53cm - 57cm |
6'4" - 6'6" | 193cm - 198cm | 29” - 34” | 73.6cm - 86.4cm | X-Large | 58cm - 61cm |
Fall in between two size categories, or can’t decide which bike size you need?
How Are Electric Road Bikes Measured?
As with conventional road bikes, e-road bikes are sized in centimetres.
Often manufacturers will also present a rough size such as medium or large alongside the frame size measurement to further assist potential customers.
Frame size measurements displayed on a road bike indicate the distance between the centre of the bottom bracket (centre of the front chainring) up to the top of the seat tube (where the seatpost is inserted).
As e-bikes are a substantial purchase, you may choose to trial ride a bike before purchase if you want to guarantee you’re selecting the best size for your height and inseam.
Electric Mountain Bike Size Chart
Rider Height | Rider Inseam | Suggested Mountain Bike Frame Size | |||
---|---|---|---|---|---|
4'10" - 5'2" | 147cm - 157cm | 24” - 29” | 60.9cm - 73.6cm | XX-Small | 13" - 14" |
5'2" - 5'6" | 157cm - 167cm | 25” - 30” | 63.5cm - 76.2cm | X-Small | 15" - 16" |
5'6" - 5' 10" | 167cm - 177cm | 26” - 31” | 66cm - 78.7cm | Small | 17" - 18" |
5'10" - 6'1" | 177cm - 185cm | 27” - 32” | 68.6cm - 81.3cm | Medium | 19" - 20" |
6'1" - 6'4" | 185cm - 193cm | 28” - 33” | 71.1cm - 83.8cm | Large | 21" - 22" |
6'4" - 6'6" | 193cm - 198cm | 29” - 34” | 73.6cm - 86.4cm | X-Large | 23" - 24" |
Fall in between two size categories, or can’t decide which bike size you need?
How Are Electric Mountain Bikes Measured?
Just like a conventional mountain bike, electric mountain bike sizes are given in inches.
Alongside the frame size in inches, it’s common to find a rough size guide such as small or extra-large. These sizes provide an easier way for consumers to estimate which bike size is best for them.
The frame size of a mountain bike is calculated by taking the distance between the middle of the bottom bracket (centre of the front chainring) and the highest point of the seat tube (where the seatpost enters the frame).
The top tube of a mountain bike normally slopes downwards from the head tube to the seat tube to provide more standover height for riders.
How To Measure a Bike Frame (How to Measure Bike Size)
Measuring a bike frame is a straightforward procedure that will allow you to identify if a bike is a suitable size for you.
The simple steps I’ve put together below will teach you how to measure bike size.
To measure a bike frame size, you’ll need a tape measure.
How to Measure a Road Bike Frame Size
The size of a road bike refers to the length of the seat tube.
Complete the following steps to determine the proportion of a road bike:
- Place the top of your tape measure on the top of the seat tube (where the seatpost is inserted).
- Holding the tape measure in place, pull it down to the centre of the bottom bracket (front chainring) and take a reading in your preferred measurement, centimetres or inches.
- Now measure your height and inseam length (steps provided here).
- Remembering these measurements, use the road bike chart above to work out if the bike is suitable for someone of your height or inseam length.
How to Measure a Mountain Bike Frame Size
The size of a mountain bike frame corresponds with the lengths of the bike’s seat tube.
The process of measuring a mountain bike is identical to that of a road bike.
It’s common for many mountain bikes to have a slightly bent seat tube. If this is the case with your bike, don’t panic.
Continue to follow the steps below, and I’ll explain how to measure correctly. All you’ll need is a tape measure.
How to Measure a Hardtail Mountain Bike Frame (How To Size a Hardtail Mountain Bike)
Here is how to find the size of a hardtail mountain bike:
- Identify the locations of your bottom bracket (centre of front chainring) and the top of your seat tube. If you need help, use my bike parts guide to point out these locations.
- Place the top of the tape measure on the top of your seat tube (where the seatpost enters the frame) and hold it in place.
- Stretch the tape measure down and align it with the centre of your bottom bracket.
- Take a reading of this measurement and use the mountain bike tables above to find the correlating height and inseam measurements.
- Compare these measurements to your own to find out of the bike is suitable for you.
How to Measure a Full Suspension Mountain Bike Frame (How To Size a Full Suspension Mountain Bike)
Here is how to find the size of a full suspension mountain bike:
- To measure the size of a full-suspension mountain bike, you’ll need to understand where the bottom bracket and seat tube are on your bike. If you’re unaware of these bike parts, use my parts of a bike guide to identify their locations.
- Next, take your tape measure and hold it on the top of your bike’s seat tube (where the seatpost enters the frame).
- Measuring in a straight line from the top of the seat tube, pull the tape measure down to the centre of the bottom bracket (centre of front chainring).
- This distance is the frame size, so take note of it and use the mountain bike size chart above to find the recommended rider height and inseam measurements for a bike of this size.
Recommended reach for MTB rider height
Reach is the distance between the centre of the head tube and the middle of the bottom bracket (centre of front chainring).
When buying a new bike, it’s essential to select the correct reach initially as this can’t be adjusted later on if you are unhappy with its size.
Determine reach by:
- Place your bike horizontally, with its back wheel touching a wall.
- Keeping your tape measure horizontal, measure the distance from the wall to the centre of the bottom bracket (centre of front chainring).
- Next, measure the distance from the wall to the top of your bike’s head tube, again keeping the tape measure horizontal.
- If you’re unsure where these bike parts are, use this simple guide to learn their locations.
- Subtract the head tube measurement from the bottom bracket measurement, and the resulting number will be your bike’s reach.
- Use the table below to determine the recommended rider height for your bike.
Mountain Bike Reach Distance Chart
Rider Height | Optimum Reach Distance | |
---|---|---|
5′2″ - 5′6″ | 157cm - 167cm | 410mm to 450mm reach |
5′6″ - 5′10″ | 167cm - 177cm | 430mm to 470mm reach |
5′10″ - 6′2″ | 177cm - 185cm | 450mm to 490mm reach |
6′2″ - 6′6″ | 185cm - 198cm | 470mm to 510mm reach |
How to Measure a Hybrid Bike Frame (How to Size a Hybrid Bike)
Measuring the frame size of a hybrid bike is done the same way as with most bike types.
To obtain an accurate bike frame size measurement, all you’ll need is a tape measure.
If you’re not familiar with the parts of a bike, this bike part guide will be helpful for taking the most accurate reading.
Follow the steps below, which are the easiest method for measuring a hybrid bike frame size:
- Align the tape measure with the top of the seat tube so that it’s touching the area where the seatpost enters the frame.
- Pull the tape measure down towards the centre of the front chainring (centre of the bottom bracket).
- Once the tape is correctly aligned with the bottom bracket, take this measurement and keep note of it.
- This distance is your frame size. If you want to find the recommended rider heights for a hybrid bike of this size, use our table, which will help you understand the ideal rider height and inseam measurements.
Can't Decide Which Size Bike You Need?
So your height and inseam place you between two bike sizes on one of the bike size charts above. Don’t panic. We can use a quick test to determine which size is best for your body size.
We can determine if you need a larger or smaller bike by measuring your ape index.
Ape index is not commonly used by bicycle manufacturers but provides a value that can help us determine between two bike sizes.
To measure your ape index follow the simple steps below.
How to Measure Ape Index For Bike Sizing
- Get a friend to measure the width of your arm span, arms stretched wide, parallel to the ground.
- Next, have your friend measure your height whilst standing against a wall.
- Once you’ve obtained your arm span and height, subtract the value of your height from your arm span.
- The final value is your ape index.
How to Choose a Bike Size With Ape Index
So we now understand that arm span minus height equals ape reach index.
But how does ape index help us if you can’t decide between two bike sizes?
Simple.
If your ape index is positive, then purchase the larger bike.
If your ape index is negative, the smaller bike of the two sizes will be a more suitable option.
However, when deciding what size bike for kids, it is more sensible and valuable to size up rather than down.
Kids are constantly growing, so they will likely outgrow the smaller bike within a short period of time.
The Most Accurate Ways to Size a Bike
Aside from using a bike size chart, here are two additional strategies to find an accurate bike size:
Try Before You Buy
Testing the bike before you purchase it may be the best way to determine if it is the correct size.
If the shop allows, go for a test ride to see how the bike feels before purchasing.
A test ride will allow you to take the bike through its paces and prevent you from ending with an ill-fitting bike.
Be wary that bike shops are there to make money off you, do your research before you go in, and don’t end up getting sold something you don’t want!
Invest In a Professional Bike Fit
Partnering with a bike fit expert is an excellent investment for ensuring the best bike size possible.
The help of a bike fit expert will only really be necessary for those that take their cycling very seriously as it will typically cost around $200 (£150).
Bike fit experts can help you choose the correct bike size, and once you’ve purchased a bike, they’ll also be able to help you adjust its components so that you minimise the stress placed on your body whilst cycling.
Some of the benefits of a professional bike fit include:
- Assistance in finding the most suitable bike size for your body shape.
- Helps to adjust components on your bike to suit your riding style better.
- Helps to prevent injury by placing less strain on your body.
How to Measure Kids Bike Size
If your child needs a new bike, their age, inseam, and height are all factors that help to determine the best fit.
Unlike adult bikes, kids bikes are sized depending on wheel diameter, not frame size.
Kids Bike Size Charts
Like measuring an adult bike frame, inseam and height are two important measurements required to choose the right size bike for a kid.
My simple kid’s bike size guide will talk you through the simple steps required to find the perfect bike size for your child.
It’s important to remember that a poorly fitting bike can put your kid off cycling for good!
My guide for kids bike sizes also covers many popular FAQs, so if you have any bike sizing questions (kids bikes), you’ll find your answers here.
Conclusion - Bike Size Chart Guide
By now, you should understand what size bike you need!
If you’ve not managed to find a suitable bike size using my bike size charts, leave me your height and inseam measurements in the comments below, along with your preferred bike type, and I’ll help you select the most suitable size.
You should also now understand how to measure the frame of a bike, which is a very straightforward task.
Should you have any questions or need assistance with finding the best bike size, get in touch and I’ll be more than happy to help.
If you need to find a bike size for your kid, use my children’s bike size charts.
As always, make sure to use a good quality bike lock to secure your bike.
Ciao for now!