When buying a new bike, the frame size is one thing you should get right. If you don’t, the bicycle just won’t fit, and that’s why you need a bike frame size chart.
As most of us like to order online, you should also consider the kind of bike you want because manufacturers size their bikes differently, and you will find frames varying from mountain bikes to road bikes. Men’s and women’s bikes are sized differently, not to mention kid’s bikes.
This guide will look at the available methods to help you size your bike correctly before making the order. I will also provide the various frame size charts you can use when buying a specific bicycle.
Let’s get started!
How Do You Size a Bike?
Bike sizing is a fundamental thing to do before buying a bike for your kid or yourself. Unfortunately, there is no universal system to follow for all bikes.
Different manufacturers size them according to type. So, whether you are looking for a kid or an adult bike, you may require other methods.
For example, while kid’s bikes are sized according to the wheel size, adult bikes are sized according to frame sizes.
Things to Consider Before Sizing Your Bike
Before we can look at the formulas to use to size your bike, there are two essential things to consider. They include
- Your Height
If you want your perfect frame size, the first thing to consider is your height. Your height guides you in choosing either a tall or short frame.
If you are tall, you will likely fit perfectly on a tall frame, while on the other hand, if you are short, the chances are that a shorter frame will suit you better.
- Bike Type
As stated earlier, frame sizing differs significantly between bike types. So, you should first know the kind of bike you want.
Many manufacturers have different frame sizes for different bike types and often size their bikes according to gender.
How to Measure Bike Frame Size?
There are three basic methods of measuring your bike frame size. They include:
Method 1 – Rider’s Height Vs. Frame Size
In this first method, you should concentrate on your height. You should know your height and then match it with the frame size as shown in the table below:
| Frame Size (in Inches) | Riders Height |
| 13 – 15’’ | 4’11’’ – 5’3’’ |
| 15 – 16’’ | 5’3’’ – 5’7’’ |
| 16 – 17’’ | 5’7’’ – 5’11’’ |
| 17 – 19’’ | 5’11’’ – 6’2’’ |
| 19 – 21’’ | 6’2’’ – 6’4’’ |
| 21’’ + | 6’4’’ + |
Method 2 – Inseam Length Vs. Frame Size
Another more straightforward method of getting your ideal bike frame size is using your inseam length. But what do we mean by inseam length?
Well, the inseam is the inside leg’s length. To measure it, you should use the steps below:
- Find a flat ground and stand straight with legs 6-8 inches apart (remember that you need to remove the shoes in this step).
- Using a tape measure, you can have a friend measure the distance from the floor to the crotch.
- Now that you have your inseam length (in cm), calculate your ideal frame size according to the bike type, as shown below:
| Frame Size (in cm) | Bike Type |
| Inseam x 0.66 | Mountain bike |
| Inseam x 0.70 | Road bike |
| Inseam x 0.64 | Trekking bike |
| Inseam x 0.665 | Hybrid/city /cruiser bike |
To make it clearer to you what I mean, consider the example below:
If you want to buy a mountain bike and your inseam is 76.5 cm, your ideal MTB frame size should be (76.5 x 0.66 = 50.49). In this case, go for a frame size of 51cm.
Method 3 – Advanced Bike Frame Chart Size
Now, if you don’t want to do the math and are looking for an ideal way to get the correct bike frame, you should consider bike frame charts. Ideally, you will find frame charts for any bike from different manufacturers.
Let’s look at the various bike frame size charts below:
Mountain Bike Frame Size Chart
Regarding mountain bikes, the frame sizes are measured in cm and inch and usually start from X-small to XXL. So, to get your correct mountain bike frame, you only need to match your height with the frame size.
Consider the table below:
| Frame Name | Frame Size | Riders Height |
| X-small | 33 – 37cm (13 – 14’’) | 148 – 158cm (4’10’’ – 5’2’’) |
| Small | 38 – 42cm (15 –16’’) | 158 – 168cm (5’2’’ – 5’6’’) |
| Medium | 43 – 47cm (17 – 18’’) | 168 – 178cm (5’6’’ – 5’10’’) |
| Large | 48 – 52cm (19 – 20’’) | 178 – 185cm (5’10’’ – 6’1’’) |
| X-large | 53 – 57cm (21 – 22’’) | 185 – 193cm (6’1’’ – 6’4’’) |
| Xx-large | 58 – 61cm (23 – 24’’) | 193 – 198cm (6’4’’ – 6’6’’) |
BMX Bike Frame Size Chart
Regarding BMX bikes, they often have standard frame sizes. However, the difference is in the wheels. Mostly, they come in 16″, 18″, and 20″. Even better, some are 24″.
Below is the BMX size chart to consider:
| Wheel Size | Age | Riders Height |
| 16″ | 5 – 7 years | 110 – 122cm (3’7″ – 4’0″) |
| 18″ | 7 – 11 years | 122 – 147cm (4’0″ – 4’10”) |
| 20″ | 11 years and above | 147– 193cm (4’10” – 6’4″) |
Road Bike Frame Size Chart
Though we have two styles of road bikes (racing and sportive), they both share the same frame sizing guide. And unlike mountain bikes, whose frame sizes are in both inches and cm, road bike’s frame sizing is only in cm, as shown below:
| Frame Name | Frame Size | Riders Height |
| Xx-small | 47 – 48cm | 148 – 152cm (4’10’’ – 5’0’’) |
| X-small | 49 – 50cm | 152 – 160cm (5’0’’ – 5’3’’) |
| Small | 51 – 53cm | 160 – 168cm (5’3’’ – 5’6’’) |
| Medium | 54 – 55cm | 168 – 175cm (5’6’’ – 5’9’’) |
| Large | 56 – 58cm | 175 – 183cm (5’9’’ – 6’0’’) |
| X-large | 58 – 60cm | 183 – 191cm (6’0’’ – 6’3’’) |
| Xx-large | 61 – 63cm | 191 – 198cm (6’3’’ – 6’6’’) |
Hybrid Bike Frame Size Chart
Hybrid bikes (including comfort bikes, commuter, dual sport, performance, and sport hybrid) usually use a common principle in sizing their bike frames. And if you look closely, their chart resembles that of a mountain bike, as shown below:
| Frame Name | Frame Size | Riders Height |
| X-small | 33 – 37cm (13 – 14’’) | 148 – 158cm (4’10’’ – 5’2’’) |
| Small | 38 – 42cm (15 – 16’’) | 158 – 168cm (5’2’’ – 5’6’’) |
| Medium | 43 – 47cm (17 – 18’’) | 168 – 178cm (5’6’’ – 5’10’’) |
| Large | 48 – 52cm (19 – 20’’) | 178 – 185cm (5’10’’ – 6’1’’) |
| X-large | 53 – 57cm (21 – 22’’) | 185 – 193cm (6’1’’ – 6’4’’) |
| Xx-large | 58 – 61cm (23 – 24’’) | 193 – 198cm (6’4’’ – 6’6’’) |
Gravel Bike Frame Size Chart
Though you can size gravel bicycles like traditional road bikes, most manufacturers provide gravel bike-specific sizing guides. Below is a gravel sizing chart that they often use:
| Frame Name | Frame Size | Riders Height |
| X-small | 48cm | 5’0″ – 5’3″ |
| Small | 50cm | 5’3″ – 5’6″ |
| Small/Medium | 52cm | 5’6″ – 5’8″ |
| Medium | 54cm | 5’8″ – 5’11” |
| Large | 56cm | 5’11” – 6’1″ |
| Large/X-large | 58cm | 6’1″ – 6’3″ |
| X-large | 60cm | 6’3″ – 6’5″ |
Trek Bike Frame Size Chart
Trek road bikes are sized like regular road bikes. However, the differences come in sizing their mountain bikes. The manufacturer uses Alpha models to size their MTBs.
Note that the height matches the alpha size that you should choose, as shown in the chart below:
| Alpha Size | Riders Height | Trek MTB Frame (in inches) |
| X-small | 147 – 155cm | 13.5″ |
| Small | 153 – 162cm | 15.5″ |
| Medium | 161 – 172cm | 17.5″ |
| Medium/Large | 170 – 179cm | 18.5″ |
| Large | 177 – 188cm | 19.5″ |
| X-large | 186 – 196cm | 21.5″ |
| Xx-large | 195 – 203cm | 23″ |
Specialized Bike Frame Size Chart
Specialized uses a different style in sizing their trail bikes. Below is a table that shows a trail bike sizing chart from specialized.com:
| Frame Size | Riders Height |
| X-small | 4’11” – 5’3″ |
| Small | 5’2″ – 5’8″ |
| Medium | 5’5″ – 5’11” |
| Large | 5’8″ – 6’2″ |
| X-large | 5’10” – 6’4″ |
| Xx-large | 6’2″ – 6’8″ |
Women’s Bike Frame Size Chart
As we all know, women are usually smaller than males. For this reason, women’s bike frames are slightly smaller than men’s. Below are road and mountain bike frame sizing guides for women:
Road Bike Frame Sizing Guide for Women:
| Frame Name | Frame Size | Riders Height |
| Xx-small | 44 – 46cm | 147 – 155 (4’10” – 5’1″) |
| X-small | 47 – 49cm | 155 – 160cm (5’1″ – 5’3″) |
| Small | 50 – 52cm | 160 – 165cm (5’3″ – 5’5″) |
| Medium | 53 – 55cm | 165 – 172cm (5’5″ – 5’8″) |
| Large | 56 – 57cm | 175 – 183cm (5’8″ – 5’10”) |
Mountain Bike Sizing Guide for Women:
| Frame Name | Frame Size | Riders Height |
| X-small | 33 – 37cm (13 – 14″) | 148 – 158cm (4’10” – 5’2″) |
| Small | 38 – 42cm (15 – 16″) | 158 – 168cm (5’2″ – 5’6″) |
| Medium | 43 – 47cm (17 – 18″) | 168 – 178cm (5’6″ – 5’10”) |
| Large | 48 – 52cm (19 – 20″) | 178 – 185cm (5’10” – 6’1″) |
Note, however, that you can use the above mountain bike sizing guide to size women’s hybrid bikes. Another note is that we generally don’t have a frame size over 6’2″ for women.
Kids Bike Frame Size Chart
Lastly, we have kids. As stated earlier, kids’ bike frames are sized differently, unlike adults. Just like BMX bikes, they are sized according to the wheel size.
So, to get the correct frame size for your kid, you need to get your kid’s inseam length and height. Still, some manufacturers also use the kids’ age to size their frames.
However, you would better go with the first option as we all know kids within the same age bracket may differ in height.
Below is the kid’s frame size chart to use:
| Wheel Size | Inseam (cm) | Rider’s Height (in inches) | Age |
| – | – | Less than 3’0″ | Less than two years |
| 12″ | 40cm | 3’0″ – 3’5″ | 2 – 4 years |
| 14 – 16″ | 46cm | 3’5″ – 3’9″ | 4 – 7 years |
| 18 – 20″ | 53cm | 3’9″ –4’5″ | 7 – 10 years |
| 24″ | 62cm | 4’5″ – 5’0″ | 10 – 13 years |
| 26 – 27.5″ | 69cm | 5’0″ | 13 years + |
What If the Bike Frame Size Isn’t Right?
Most times, we may get the size wrong. That is evident when you buy a bike that is too big or too small. So, what should you do in such a case?
If your bike is too big, you should buy a shortened stem and replace the long one, shorten your seat post, and you can still also move your saddle forward.
But in case the bike is too small, you should buy a longer stem and replace the short one, adjust the seat post, or you can move the saddle backward.
What Size Is A 20-Inch Bike Frame?
A 20-inch frame is ideal for adults whose height is within 6’2″ – 6’4″.
Closing Remarks
I hope the above bike frame size chart guide will help you size your bike frame the next time you want to invest in a new bike. Remember, men’s and women’s bikes are sized differently. Still, the size varies by type and brand.
So, decide on the bike you want, and then use the sizing guides above to get your correct frame size.
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