There is no reason to be uncomfortable on your bike! Riding is a fun exercise, and you should enjoy every bit of it. However, riding a bike that doesn’t fit you can be unpleasant, not to mention the pains and discomfort that accompanies every ride.
So, we’ve put together this useful guide on bike sizes that makes choosing the proper size a lot simpler.
Let’s get started!
| Height in cm | Height in feet | Frame size | Bike size |
| 147–152 cm | 4ft 10in–5ft 0in | 47–48 cm | XXS |
| 152–160 cm | 5ft 0in–5ft 3in | 49–50 cm | XS |
| 160–170 cm | 5ft 3in–5ft 7in | 51–53 cm | S |
| 170–175 cm | 5ft 7in–5ft 9in | 54–55 cm | M |
| 175–180 cm | 5ft 9in–5ft 11in | 56–58 cm | L |
| 180–188 cm | 5ft 11in–6ft 2in | 59–60 cm | XL |
| 188–196 cm | 6ft 2in–6ft 5in | 60–61 cm | XXL |
| 196 cm+ | 6ft 5in+ | 62–63 cm | XXXL |
How are road bikes measured?
Using the standard provided by a bike manufacturer is the best way to find a bike that fits you. However, bicycle manufacturers do not use standardized sizing.
Therefore, it’s helpful to have a general understanding of bike geometry because each will have a different approach to bike design.
Having said that, road bikes are often sized by measuring the lengths of certain parts of the bike frame (such as the top tube length), and these sizes correlate with different height ranges.
Don’t assume that a model will fit the same as another just because the advertised size appears to be the same because how one manufacturer sizes its bikes may differ greatly from another.
To help us compare bike sizes and geometry between different brands, bike manufacturers will also provide stack and reach values for their models.
The benefit of using these values is that they don’t depend on the angle of the frame; for example, two different frames might have the same reach but different top tube lengths, with the angle difference accounting for the length difference.
The measurements for each part of a bike’s geometry are often given by the manufacturer, so understanding what each value means will help you know what bike sizes will fit you best.
Seat Tube Length
The seat tube length was originally used to size road bikes. Seat tube length is the distance between the top of the seat tube down to the center of the bottom bracket.
The seat tube is typically measured in centimeters, with the small end beginning at roughly 46 cm and the large end at about 64 cm.
As you might expect, the length of this distance will affect the measurement of every other part of the frame. And to accommodate people of sizes, bike manufacturers offer a wide selection of frames to accommodate the many body types that exist.
Road bikes have evolved, and the geometry of their frames has changed, therefore measuring the seat tube is no longer an accurate method of sizing.
However, the seat tube is still one of several important parameters that determine the size of a road bike frame.
The other key metrics and their effects on frame size and handling are discussed below.
Effective top tube length
Seat tube length is often used to indicate size, but top tube length is crucial for determining the proper fit.
The effective top tube length is the length of the highest horizontal tube on the bike frame.
If a bike has a sloped top tube, then the effective top tube length is measured as the distance between the head tube and the seatpost.
The effective top tube length affects the reach on a bike. The reach is the distance between your hands and your seat, and this affects your position of your upper body on the bike.
If the top tube is too long, you will have a longer reach and your body will be in an upright position, which can be uncomfortable on long rides.
A shorter effective top tube will give you a shorter reach.
The perfect reach is when the angle between your arms and your torso is 90-degrees.
Standover Height
Standover height is the distance between the top tube (highest horizontal tube on the bike) and the ground. This measurement is important in determining if a bike is the right size for you.
When you straddle a bike, there should be at least 1 or 2 inches of space between your crotch and the top tube. This means that you should be able to lift the bike off the ground while you’re standing over it, this gives you enough room to quickly mount and dismount from the bike.
If you’re shopping online for a bike, a simple calculation can help you determine the clearance between your crotch and the top tube.
A bike might be a good fit for you if your inseam length (the distance between the floor and your crotch) is 1 or 2 inches higher than the bike’s standover height.
Head Tube length
The head tube length also affects how your body is positioned when riding. Head tube length is the distance from the top to the bottom of the head tube. A longer head tube will put the handlebars higher and closer to your body, which puts you in a more upright riding position for comfortable and endurance.
While a shorter head tube will put the handlebars lower and give the rider a more tucked and aggressive riding position which is great for aerodynamics.
Stack and Reach
In any given bike, you can only adjust the saddle position, stem length and headset spacers to a certain extent. The stack and reach values of a bike determine how much adjustment you can make and what riding positions you can get on that bike.
Basically, it can determine if a bike will fit you or not. The stack of a bike is the vertical distance between the center of the top of the head tube and the bottom bracket, while the reach is the horizontal distance between the center of the top of the head tube and the bottom bracket.
How to measure yourself for a road bike
Your height and inseam length and two specific body measurements that will help you to get an accurate bike fit.
While your height helps you find the correct bike height for you, your inseam length will determine if you can comfortably straddle and pedal the bike. Taking your height and inseam measurements are absolutely necessary in finding the best-fit bike for you.
Measure your height:
- Get a tape measure and a pencil.
- Stand straight up against a wall with your shoes removed.
- Keep your shoulders back and stare straight ahead.
- Use a pencil to mark the top of your head against the wall.
- Then use a tape to measure your from the mark on the wall to the floor.
Measure your inseam:
- Get a tape measure, pencil, and a thick hardcover book.
- Wear your cycling shoes and stand against a wall.
- Place the book between your legs, make sure it’s snugly nestled against your crotch
- Use the pencil to mark the spot where the top edge of the book meets the wall
- Measure from the mark on the wall to the floor (in inches or cm). This is your inseam length.
You can calculate your bike size with your height and inseam measurements.
| Rider height | Inseam length | Frame size | |
| Feet and inches | Size in cm | Size in cm | Bike size |
| 4ft 10in – 5ft 0in | 66 cm | 47-48 | XXS |
| 5ft 0in – 5ft 3in | 69 cm | 49-50 | XS |
| 5ft 3in – 5ft 6in | 71 cm | 51-53 | S |
| 5ft 6in – 5ft 9in | 76 cm | 54-55 | M |
| 5ft 9in – 6ft 0in | 79 cm | 56-58 | L |
| 6ft 0in – 6ft 3in | 81 cm | 58-60 | XL |
| 6ft 3in – 6ft 6in | 91 cm | 61-63 | XXL |
How to calculate your bike size
We’ll use basic math to determine the ideal bicycle size. To get your bike frame size in centimeters, multiply your inseam measurement by 0.70 for road bikes, or by 0.685 for mountain bikes.
- Road bike: 0.70 x Leg inseam = Your frame size (cm)
- Mountain bike: 0.685 x Leg inseam = Your frame size (cm)
Check your Apex Index
Your height and inseam measurements can place you in the middle of two size ranges. Some riders may find themselves unable to choose between frame sizes while shopping for a new bike.
If you find yourself facing a choice between sizes and having to decide whether to go for a larger or smaller frame. You can decide which bike to go for using your ape index.
Your ‘Ape Index’ is your arm span to height ratio.
Your arm span is determined by measuring the distance between the tip of the middle finger on one arm to the tip of the middle finger on the other arm, with the arms extended at right angles to the body, and palms facing forward.
Choose a larger frame if your arm span is greater than your height. And if your height is greater than your height, then a smaller bike frame will fit you better.
The reasoning behind this is that the reach on bigger frame sizes is longer than the reach on smaller frame sizes.
Therefore, a rider with a longer arm span needs a longer reach to the handlebars, and a rider with a shorter arm span will need a shorter reach to the handlebars.
Bike Frame Geometry: Traditional vs Compact vs Semi-compact
When purchasing your first bicycle, you should also consider the different bike frame geometries; traditional, semi-compact, and compact frame.
Traditional bike frames have a horizontal top tube that is parallel to the ground. These were the original design for bikes and were more popular in the past. Now, modern bike frames are more likely to have a compact or semi-compact bike frames.
Compact geometry frames have a sloping top tube, a smaller rear triangle, and a shorter wheelbase. As a result, there is more standover clearance than with a frame with traditional geometry, and the ride may be firmer and more responsive.
Compact and semi-compact bike frames are almost the same. In fact, the only difference between semi-compact and compact geometry is the lower sloping angle of the top tube, which reduces standover clearance and increases effective top tube distance.
When sizing bikes with traditional frame geometry, you’d look for 1 or 2 inches standover clearance, but with compact and semi-compact bikes, you’d see more than 2 inches standover clearance.
More tips for choosing the best road bike for you
The two major considerations when choosing a new road bike are your budget and what you need the bike for. Think about why you’re getting a bike; is if for commuting, recreational rides on weekends, touring, or racing?
Taking a few minutes to think of why you need a new bike will help you determine the type of bike that best suites your needs.
Consider the bike type: Endurance vs Race
Race and endurance bikes are the two main broad categories for road bicycles. These bike meet different needs, therefor they slightly differ in their design.
While endurance bikes are made for long comfortable rides, race bikes are designed for racing and speed.
Race bikes are made to be more compact and lightweight, they have more aggressive geometry for quick handling and can achieve riding positions that give riders an aerodynamic advantage.
With endurance bikes, riders can achieve a more upright position, which is more comfortable and great for long distance rides.
Whether endurance or road bikes, you should budget from $500 above for a high-quality bike that will provide you years of stressful service.
Consider the frame material
When it comes to bike frame material, your options are aluminum or carbon fiber.
Bikes with carbon-fiber frames are general more expensive than bikes with aluminum frames.
This is probably because carbon-fiber frames provide smoother rides because they are able to absorb road vibrations more efficiently.
Aluminum frames also provide smooth rides, but they are less expensive because they are a bit easier to manufacture.
Also, most road bikes with aluminum frames have a hybrid carbon fiber front fork to reduce road vibrations and provide smoother rides.
Before you decide which frame material will be better for you, again think of why you need the bike.
A carbon-fiber frame will be the better option if you want the lightest and sturdiest bike. While an aluminum frame will work well for you if you typically bike for recreation and fitness rather than for speed.
Invest in a bike fit
A bike fit helps to perfect your relationship with the bicycle and greatly improve your riding experience.
The objective of a bike fit is to maximize your comfort when riding the bike and get rid of any pains and discomfort. You will enjoy riding more because it improves your bike control and cycling efficiency.
In a professional fitting, your ideal seat position and horizontal alignment, reach and drop to the handlebars, body angles and correct riding position are all determined from observations, measurements, and adjustments.
FAQs on Road bike size
How do I size myself for a road bike?
If you’re shopping for a bike online and wondering how to measure yourself, simply take your inseam measurement and subtract two centimeters from it. This will give you the ideal standover height for a bike that fits you.
How do I know if my bike is too big?
A bike frame is too big for you if you feel pain and discomfort after riding, or you have to sit up straight to reach the handlebars. If you also struggle to make turns or ride as fast as you want, then the bike frame may be too big for you.
How important is the correct bike frame?
Getting a bike with the correct frame size for you is the number 1 most important part of choosing the right bike. A bike frame size affects every adjustment that cam be made on the bike.
No matter how many adjustments you make, you can’t achieve the best riding position for you if your bike frame is not the right size for you.
Is a bigger bike frame better?
Bikes with larger frames are more likely to be uncomfortable due to incorrect riding posture. Not riding in the correct body position will put your knees, shoulder, neck, back, wrist and arms under stress, which will cause you pain after your rides.
A person can fall between two size categories based on their height and inseam measurements. If this applies to you, use your apex index to choose the bike that will fit you the best.
Wrapping Up
We have covered guidelines for choosing the right bike size. Keep in mind that getting the right size is essential if you want to have a relaxing and enjoyable ride. Before you make your final decide on a bike purchase, make sure that you feel absolutely confident and comfortable on your new two-wheeler ride.
Once you have the bike with the perfect frame size for you, next will get it the right fit, and we have a bike fitting guide for you. Be sure to check it out. Happy riding!
