With gas prices continuing to soar, more people than ever are rediscovering the joys of cycling.
People purchase bikes for many different purposes. Some of the most common of these include:
- Mountain biking
- Road biking
Whatever your reason for buying a bike, it’s vital to choose the correct bike frame size. Today’s guide will help you to pick the right frame size for mountain bikes, road bikes, and the hybrid bikes often used by commuters.
Why Is a Bike Frame So Important?
If you don’t get the frame size of your bike right, you will likely find riding it to be an uncomfortable experience. You may also struggle to pedal the bike effectively.
When a bike frame is too small, you’ll find that both your legs and your torso are too restricted. This prevents you from fully extending your legs and you won’t be able to attain maximum power when cycling.
Conversely, when a bike frame is too large, your legs cannot rotate fully enough to achieve high speeds when cycling.
If you have the bike in front of you, you can quickly check the appropriateness of the frame size. Just stand over the frame with both feet planted on the ground. If the frame is the right size for you, there should be an inch of clearance between the frame and your crotch, regardless of whether the frame is for a mountain bike, a racing bike, a hybrid bike, or a touring bike.
We appreciate that many people choose to buy their bikes online, though, so as you read on today, you’ll find several bike frame size charts for the most popular bike types. This will enable you to pick the right frame for your height with relative ease.
Quick Tips for Determining Your Bike Size
There is a quick and simple formula that can help you determine the correct bike frame size for your needs:
- Bike type x leg inseam = frame size (cm)
Choose from the following bike types and use the multiplier provided:
- Road bikes (x 0.7)
- Mountain bikes (x 0.685)
- City bikes (x 0.685)
Next, measure your leg inseam after removing your shoes.
As an example of the formula in action, if you are looking for a road bike and your leg inseam measures 65cm, the right frame size is:
- 65 x 0.7 x 45.5cm
More About Frame Sizes
Before we break down the main types of bikes and the various frame sizes available, familiarize yourself with these basic terms applicable to mountain bikes:
- ETT (effective top tube): The top tube is the horizontal distance between the head tube and the seat tube. This tube comes into play when you are measuring a mountain bike.
- Reach: This is a term used for the space between the bottom bracket and the center head tube. Many mountain bikers use reach to measure the length of a mountain bike.
- Stand over: You’ll need more clearance between the top tube and your crotch on a mountain bike than on other types of bikes. Look for at least three inches clearance. This will enable to you to more easily jump free in the event of a collision or slip on the trail.
Mountain Bike Frames
The sizing conventions used for modern mountain bikes differ to those for road bikes.
Before 2000, mountain bikes utilized the same frame geometry as road bikes but married to a wheel with a smaller diameter with bottom brackets positioned further from the ground. Longer cranks permitted more leverage when climbing steep hills, while flat handlebars promoted superior side-to-side control. These older bikes had sizes from 16.5 inches to 21 inches.
After 2000, many bike manufacturers switched to a small, medium, and large sizing convention. As a rough guide:
- Small mountain bike frames are ideal for people from 4’11” to 5’4”.
- Medium mountain bike frames are ideal for people from 5’5” to 5’9”.
- Large mountain bike frames are ideal for people from 5’10” to 6’3”.
As you’ll see from our detailed sizing chart below, you can also find extra-small and extra-large frames for those falling outside the above parameters.
With mountain bikes, seating positions are typically less aggressive than those on road bikes. You don’t need to hunch yourself over to attain more speed and you should ensure that your head is positioned up so you can better spot any obstacles on the trailhead.
Next, a quick reference frame size chart to help you choose the right mountain bike.
Frame Size Chart for Mountain Bikes
- XS for heights from 4’11” to 5’2” – frame size of 13” to 14”
- S for heights from 5’2” to 5’6” – frame size of 15” to 16”
- M for heights from 5’6” to 5’10” – frame size of 17” to 18”
- L for heights from 5’10” to 6’1” – frame size of 19” to 20”
- XL for heights from 6’1” to 6’4” – frame size of 21” to 22”
- XXL for heights from 6’4” to 6’6” – frame size of 23” to 24”
Road Bike Frames
Road bikes are normally sized according to the dimensions of their seat tubes – this is the distance between the center of your bracket cup and the top of your seat tube.
That said, this is not the only salient dimension to consider when sizing a road bike. You also need to look at the top tube measurement. Additionally, the reach of the handlebar and the length of the stem are also important if you want the right fit. These measurements will affect the angle of your back as you ride. Some riders prefer a longer reach allowing them to hunch over for more aerodynamics. Casual cyclists may prefer a less aggressive angle for a less harsh experience on the back.
Seat tubes for road bikes are measured in centimeters. A small is around 46cm and a large roughly 64cm. The longer this distance, the longer the other frame measurements will be.
Next, a quick reference frame size chart to help you choose the right road bike.
Frame Size Chart for Road Bikes
- XSS for heights from 4’8” to 5’1” – frame size of 142-155 cm (44)
- XS for heights from 5’1” to 5’4” – frame size of 155-163 cm (48)
- S for heights from 5’4” to 5’7” – frame size of 163-170 cm (51)
- M for heights from 5’7” to 5’10” – frame size of 170-178 cm (54)
- L for heights from 5’10” to 6’0” – frame size of 178-182 cm (56)
- XL for heights from 6’0” to 6’3” – frame size of 182-190 cm (58)
- XXL for heights from 6’3” to 6’5” – frame size of 190-196 cm (60)
- XXXL for heights from 6’5” to 6’9” – frame size of 196-206 cm (62)
More and more road bike manufacturers are now using a small, medium, and large sizing convention.
Beyond this, some manufacturers have also altered frame geometry on road bikes. One of these changes is the inclusion of sloping top tubes more in line with those normally found on mountain bikes.
Hybrid Bike Frames
Hybrid bikes are popular for leisure riding and commuting both.
Many of these bikes borrow from mountain bike styling but they are equipped with thin, smooth tires for less resistance on the road. Unlike road bikes, though, hybrid bikes feature flat handlebars.
Next, a quick reference frame size chart to help you choose the right hybrid bike.
Frame Size Chart for Hybrid Bikes
- For heights from 4’11” to 5’2” – frame size of 13” to 14”
- For heights from 5’2” to 5’6” – frame size of 15” to 16”
- For heights from 5’6” to 5’10” – frame size of 17” to 18”
- For heights from 5’10” to 6’1” – frame size of 19” to 20”
- For heights from 6’1” to 6’4” – frame size of 21” to 22”
- For heights from 6’4” to 6’6” – frame size of 23” to 24”
Whatever type of bike you prefer, we hope today’s bike frame size charts and guide have helped you gain a better understanding of sizing.
The most important thing to consider before whipping out your credit card is the type of bike frame in question. We outline the minor differences you will find on mountain bikes, road bikes, and hybrid bikes so you can more easily navigate choosing and buying a bike online.
Here at Florida Cycling we cater for all levels of cyclist from beginners to competitive riders. As we continue to add more content over the coming months, we’ll be including plenty of beginner-friendly guides so you can get started with a new hobby without too much confusion.
Taking the time to get the sizing of your new bike right will improve comfort and performance, so let us know in the comments if you have any questions. We suggest you bookmark our blog before you head off and we hope to see you very soon!