You can find as many different bikes as reasons for individuals buying them, so you can see why it is a challenge to end up knowing what size bike I need. It would be best if you determined the right size bike before you buy, and one of the best ways it try specific bike sizes at the bike shop on a test ride.
However, it isn’t always possible, such as if you are buying the bike for a gift or want to buy bike online. Then you’ll need to know what size bike frame I need. To help there is a simple formula you can use, or you can check our bike frame size charts, to help.
In our guide, we have a bike frame size chart to cover:
- Mountain bikes
- Children’s bikes
- Hybrid bikes
- Road bikes, and more.
By the end, if you can’t go to the bike shop, so long as you have the child’s height, inseam length, body length, and arm length, you can buy a bike online. You can also get the correct size bike that will fit as your child grows. (Read Snap Swivel Size Chart)
How Do You Work Out Your Bike Size?
Because there isn’t usually one universal system of measurement that applies to all bike frame sizes, bike types, and riders, sizing road and mountain bikes can be a real challenge.
There are many ways manufacturers use it, and it differs if you are shopping for an adult bike, a road bike, a mountain bike, or you need kids’ bike sizes.
Adult Bike Sizing vs. Kid Bike Sizing
The wheel measures kids’ bikes, while the frame measures adult bikes. This implies that the measurement systems for adult and child bikes are different.
Children 12 years old and less will typically fit on bikes that are measured by the size of the wheels, yet as they get older, they will undoubtedly fit on small adult bikes.
Thus, a kids bike size chart can be governed by age, yet there are different-sized kids, so a child’s bike size will vary from kid to kid.
Women’s Bike Sizing
There isn’t much difference between men’s and women’s bike sizes, although some businesses offer women-specific versions with designs that combine better-fitting components.
Road Bike Sizing Vs. Mountain Bike Sizing
Sizing might also vary between bike styles or the manufacturer, which can further complicate matters. For instance, different numerals are frequently used to designate sizes for road bikes and mountain bikes.
The seat tube and other key bike components were measured without going into too much detail to determine the bike’s size. However, as bike geometries have changed significantly over time, manufacturers have updated their measurement system. (Read Jig Hook Size Chart)
How To Calculate Your Bike Size:
This approach will use basic math to determine the ideal bike size before looking at the bike size charts below.
Bike Rider Dimensions
- Bike type times leg inseam equals your frame size (in centimeters)
Use the following calculation to determine the proper bicycle size:
- Road bikes: x 0.70
- Mountain bikes: x 0.685
- City bike: x 0.685
Take your tape measure, and measure the length between the bottom of your leg and the crook of your pants by taking off your shoes, standing straight, and spacing your legs 15 to 22 cm apart.
Note: most manufacturers use the metric system, so ensure your tape measure reads in this, or your bike fit will be way out, and you won’t get the right size frame.
Calculate:
- Road bike: 0.70 x Leg inseam = frame size in cm
- Mountain bike: 0.685 x Leg inseam = frame size in cm
- City bike: 0.685 x Leg inseam = frame size in cm
Sizing a Mountain Bike
Mountain bike fit differs from other bikes. A mountain bike fit has to match your physique because of the dangerous trails you ride.
When pedaling, your leg bends slightly at the bottom of the stroke. Therefore, your leg should be 80 to 90% extended so you can climb hills and bike across harsh flat terrain.
Mountain Bike Fit
Standard-sized mountain bike size bike have different geometry, so how you ride matters. It would be best if you also considered the top tube length, stand-over clearance, seat height, and reach because mountain bike differs from road bike in size and design.
Standover Height
Standover height is the distance between the top tube and the ground when standing over the bar.
You’ll need at least an inch of standover room for most bikes. Pull the bike until it reaches your body while standing to test this. If you can raise the wheels one inch, you should have enough room.
Leg Extension
After ensuring you have ample standover room, extend your legs. You can change the seat height; however, if your legs are still bent when pedaling, you may require a larger size.
Reach
Reach is the horizontal distance between the head tube and the bottom bracket. How far you must reach the handlebars determines this.
Longer reaches make a bike feel “roomier,” more stable at speed, and more assured on unsteady ground. The bike will feel more responsive with a shorter reach, but you might not want that. (Find the Best Mountain Bike Shoes)
Mountain Bike Wheelbase
With a mountain bike, you need the extra standover inches with the right frame so you can jump off. You can jump off the bike with adequate space between you, the bike’s top tube bar, and the saddle.
Mountain Bike Top Bar and Size
The extreme top bar slope in the right frame may change the inches needed to ride the bike properly.
Standover height isn’t a good measure of a mountain bike’s fit. When buying a mountain bike, you must examine all other factors. When descending, your seat should be 3 inches lower than when climbing.
Most mountain bike fans ride with a dropper seat-post that allows you to raise or lower the saddle with a button to rapidly adjust your riding to the terrain without dismounting. One thing to note is the top tube length on women’s mountain bikes.
These can sit in a lower position than on a man’s bike. In addition, you can see more of this difference in road and mountain bikes, as road bikes will have a lower sitting tube and smaller tire size.
Hybrid Bike Size Charts
Hybrid bikes, such as commuter and exercise bikes, are excellent all-rounders, incredibly adaptable, and frequently reasonably economical.
Most hybrid bikes use the Small/Medium/Large sizing system; however, you may come across a few manufacturers who still use inches to show size.
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| Size | Height | Inseam |
| S | 155.0 – 165.0 cm 5’1″ – 5’5″ |
72.0 – 78.0 cm 28.3″ – 30.7″ |
| M | 165.0 – 175.0 cm 5’5″ – 5’8″ |
77.0 – 83.0 cm 30.3″ – 32.7″ |
| L | 175.0 – 186.0 cm 5’8″ – 6’1″ |
82.0 – 88.0 cm 32.3″ – 34.6″ |
| XL | 186.0 – 197.0 cm 6’1″ – 6’5″ |
87.0 – 93.0 cm 34.3″ – 36.6″ |
| XXL | 197.0 – 203.0 cm 6’5″ – 6’7″ |
92.0 – 95.0 cm 36.2″ – 37.4″ |
Bike Size Charts for Kids
Kids’ bikes are both slightly more difficult and slightly simpler to size. To keep your child on the ideal size bike, you’ll spend a lot of money upgrading bikes as they grow.
In addition, kids frequently change their minds about what they want to do, and cycling can become an expensive sport. Simply making things a little bigger and letting them grow into them is a popular tactic.
The measurement you frequently look at for children’s bikes is the wheel size. They sell bikes with wheels of 12 inches, 14 inches, 16 inches, 18 inches, 20 inches, and 24 inches.
If these frames seem too small, a small adult 26-inch wheel-size bike can fit them. Below, you will find a basic bike size chart for kids:
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| Size | Height | Age (Average) |
| 12″ wheel | 86.0 – 102.0 cm 2’9″ – 3’4″ |
2 – 4 |
| 16″ wheel | 99.0 – 117.0 cm 3’3″ – 3’10” |
4 – 6 |
| 20″ wheel | 114.0 – 132.0 cm 3’8″ – 4’4″ |
6 – 8 |
| 24″ wheel | 130.0 – 150.0 cm 4’3″ – 4’11” |
8 – 12 |
| 26″ wheel | 146.0 – 160.0 cm 4’9″ – 5’3″ |
12 + |
Here you can find a bike size chart that covers height, so if you have a big kid, you don’t have to stick to the above chart for age.
Bike Size Chart/Bike Frame Size Chart
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| Height | Bike Size |
| 4’11” to 5’3” (150-160 cm) | 13 to 15 inches |
| 5’3” to 5’7” (160-170 cm) | 15 to 16 inches |
| 5’7” to 5’11” (170-180 cm) | 16 to 17 inches |
| 6’0” to 6’2” (180-188 cm) | 17 to 19 inches |
| 6’2” to 6’4” (188-193 cm) | 19 to 21 inches |
| 6’4” and above (193+ cm) | 21 plus inches |
When you look at a balance bike, things differ slightly from size kids’ bike. NEVER buy a bike with a minimum seat post height of over 1-3 inches above your child’s inseam.
If it is, they won’t be able to put their feet flat on the ground. The correct frame size means they can have feet flat, a top tube to hit, and balance, which is the point until they have a more extensive bike type with pedals. (Find the Best Bike Repair Stand)
Road Bike Size Chart
Road bikes and bike manufacturers use measurements in centimeters or the metric system to denote frame sizes and the correct bike fit.
Start by measuring the seat tube of a road bike if you are considering buying one but are unsure of its size.
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| Size | Height | Inseam |
| 47 | 152.0 – 158.0 cm 4’11” – 5’2″ |
71.0 – 75.0 cm 28.0″ – 29.5″ |
| 50 | 158.0 – 163.0 cm 5’2″ – 5’4″ |
74.0 – 77.0 cm 29.1″ – 30.3″ |
| 52 | 163.0 – 168.0 cm 5’4″ – 5’6″ |
76.0 – 79.0 cm 29.9″ – 31.1″ |
| 54 | 168.0 – 174.0 cm 5’6″ – 5’8″ |
78.0 – 82.0 cm 30.7″ – 32.3″ |
| 56 | 174.0 – 180.0 cm 5’8″ – 5’10” |
81.0 – 85.0 cm 31.9″ – 33.5″ |
| 58 | 180.0 – 185.0 cm 5’10” – 6’0″ |
84.0 – 87.0 cm 33.1″ – 34.3″ |
| 60 | 185.0 – 190.0 cm 6’0″ – 6’2″ |
86.0 – 90.0 cm 33.9″ – 35.4″ |
| 62 | 190.0 – 195.0 cm 6’2″ – 6’4″ |
89.0 – 92.0 cm 35.0″ – 36.2″ |
Mountain Bike Size Chart
Mountain bikes will either be sized in inches or—more likely—you’ll see a new bike fall into the Small/Medium/Large hierarchy that caters to consumers. The geometries of newer mountain bikes have changed so much that it’s challenging to find the right size bike without the aid of a sticker or stamp on the frame.
As a result, measuring tubes in the simple formula often won’t provide beneficial information or the perfect fit.
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| Height | Inseam | ||
| XS | 13.5″ | 137.0 – 155.0 cm 4’5″ – 5’1″ |
64.0 – 73.0 cm 25.2″ – 28.7″ |
| S | 15.5″ | 153.0 – 166.5 cm 5’0″ – 5’5″ |
72.0 – 79.0 cm 28.3″ – 31.1″ |
| M | 17.5″ | 161.0 – 172.0 cm 5’3″ – 5’7″ |
76.0 – 81.0 cm 29.9″ – 31.9″ |
| M/L | 18.5″ | 165.5 – 179.0 cm 5’5″ – 5’10” |
77.0 – 84.0 cm 30.3″ – 33.1″ |
| L | 19.5″ | 177.0 – 188.0 cm 5’9″ – 6’2″ |
83.0 – 88.0 cm 32.7″ – 34.6″ |
| XL | 21.5″ | 186.0 – 196.0 cm 6’1″ – 6’5″ |
87.0 – 92.0 cm 34.3″ – 36.2″ |
| XXL | 23.0″ | 195.0 – 203.0 cm 6’4″ – 6’7″ |
92.0 – 95.0 cm 36.2″ – 37.4″ |
FAQs
What size bicycle is right for my height?
Before deciding on a bike size, choose a type. Road and mountain bikes use a separate sizing system, so decide what you want first, then study a bike size chart to get the right bike.
Should I put my feet flat on the ground on a bike?
The seat is too low if you can place your feet flat on the ground while seated. If your seat is excessively low, your knees will be overbent during pedaling, causing pain and inefficiency.
Should legs be straight when riding a bike?
Your leg shouldn’t be completely straight or unduly bent on the downstroke. Try to bend your knee 15-20° on the downstroke, or arrange your seat so your heel can reach the pedal axle. Finding what works for you is essential.
How much does a bike fitting cost?
Professional bike fitting is more accurate and thorough than bike shop advice. However, a good bike shop could offer professional bike fitting to maximize comfort and performance for racers, triathletes, and those who want the perfect size BMX bikes for stunts, etc.
Do I need a 26 or 29 bike?
26-inch wheels were once the mountain bike standard, but most mid- and upper-tier bikes today use 29- or 27.5-inch wheels.
29ers and 27.5+ bikes have quicker top speeds and roll over obstacles easier than 26-inch wheels. 26-inch wheels are perfect for kids who have outgrown their 24-inch kids’ bikes but aren’t big enough for adult bikes.
What size is a 26-inch bike?
26 inches refers to the wheel size. Thus that figure isn’t necessarily the greatest method to estimate bike size. Some juvenile bikes have 26-inch wheels, but most adult bikes do.
