What Size Gravel Bike Do I Need?

Choosing the right gravel bike size is key for comfort and being able to get the maximum out of your new bike.

If you are having doubts, we've got experts in store at Hampton Wick and Oakham who have fitted many gravel bikes over the years and will be happy to help you with a professional bike fit. Alternatively, speak to our online experts who can help with gravel and road bike sizing.

How to measure yourself for a gravel bike?

Accurate measurements of height and inner leg length are essential for determining the correct gravel bike size, with these details significantly influencing performance.

Rider Height and Leg Length

Height and inner leg length are crucial for bike sizing. Accurately measure your inside leg length and use it with your height. To do this, start by marking the wall at the top of your head and measuring from the floor to the mark, then using a tape measure, measure your inside leg length by standing against a wall with a book between your legs and measuring from the top of the book to the floor.

How is a gravel bike measured?

A gravel bike is typically measured by its frame size, which is determined by the length of the seat tube. The bike's geometry also plays a role, with important dimensions like the top tube length, reach, and stack affecting fit and handling.

Seat Tube Length: This is the distance from the centre of the bottom bracket to the top of the seat tube.

Top Tube Length: This is measured horizontally from the centre of the seat tube to the centre of the head tube.

Reach and Stack: Reach is the horizontal distance from the bottom bracket to the top of the head tube, while stack is the vertical distance between these two points.

Bottom Bracket Drop: This is the vertical distance from the bottom bracket to the line through the front and rear axle.

Additionally, the wheel size, commonly 700c, and tyre clearance are important measurements that determine the bike's versatility for different terrain types.

Gravel Bike Size Chart

Unfortunately many bike brands use differing size calculators to suggest the best size, considering factors like height and inside leg measurements so be sure to check each individual bike sizing information to ensure the bike is correct for you. Frame sizes vary between brands, so a “medium” in one brand might fit differently than a “medium” in another.

Below is our gravel bike size chart, which can be used as a rough guide.

Stack and Reach

Stack measures the vertical distance from the bottom bracket to the top of the head tube, indicating how upright you’ll sit. A higher stack provides a more upright and comfortable position, beneficial for long rides.

Reach measures the horizontal distance from the bottom bracket to the top of the head tube, affecting how stretched out you’ll be. Both measurements are crucial for handling on gravel bikes.

Top Tube Length

Top tube length, the horizontal distance between the head tube and seat tube length, also impacts your riding position. A longer top tube can lead to a more stretched-out position, preferred for aggressive riding styles, while a shorter top tube offers a more upright posture. Choosing the correct top tube length tailored to your anatomy ensures less fatigue and greater efficiency on long rides.

Head Tube Angle

The head tube angle significantly affects handling and stability on different terrains. A slacker head tube angle provides more stability, ideal for rough and technical trails, while a steeper head tube angles offers quicker, more responsive handling, beneficial for smoother, less technical rides.

Fine-Tuning Your Gravel Bike Fit

While selecting the correct frame size is crucial, adjusting components like the saddle, stem, and handlebars can significantly enhance your riding experience. These adjustments tailor the bike to your unique body proportions and preferences, ensuring a perfect fit for any terrain.

At Sigma Sports, we offer a custom build service, should you wish to handpick every detail of your bike to incorporate different features from different models to create the dream gravel bike. Alternatively, a professional bike fit may unlock the perfect set up if you are planning bikepacking trips on a ready built bike.

Adjusting Saddle Height and Position

A slightly lower saddle height makes quick dismounts and maneuvering over obstacles easier, enhancing overall safety. Ensuring adequate standover height is also crucial for safely mounting and dismounting, especially on rough terrains.

Stem and Handlebar Adjustments

Using shorter stems can enhance reach and handling, making the bike more responsive. Additionally, adjusting the saddle position along the rails or switching to a different saddle can further fine-tune your fit.

Tyre Selection and Pressure

Appropriate tread patterns enhance traction on gravel surfaces. Wider tyres improve comfort and grip on rough terrain, while correct tyre pressure prevents pinch flats and enhances ride quality. Adjusting gravel tyre pressure according to riding conditions and rider weight optimises performance.

Special Considerations for Gravel Bikes

Gravel bikes tend to combine features of road, cyclocross, and mountain bikes, making them versatile for various terrains. From geometry to component adjustments, several factors ensure a perfect fit and performance on gravel bikes.

Bottom Bracket Drop

The bottom bracket drop is crucial for stability and ground clearance on rough terrain. A higher bottom bracket increases clearance, vital for navigating technical trails. Conversely, a lower bottom bracket drop enhances stability by lowering the bike’s center of gravity.

Tyre Clearance

Wider tyres improve traction and comfort on rough terrain, and so gravel bikes accomodate a wider tyre clearance.

What to Do If You're Between Sizes

If you’re between different sizes, consider how the bike fits your intended use. Both smaller and larger sizes have their own benefits and considerations; choose based on personal preferences and riding style to avoid going for the wrong size.

Opting for the Smaller Size

Choosing a smaller gravel bike size can enhance control and comfort on rough terrain. It allows for a more upright riding position and accommodates preferences like shorter stems and reduced risk of toe overlap. This bike sizing option is particularly beneficial for tight corners and technical trails, providing a more responsive feel.

Opting for the Larger Size

Opting for a larger gravel bike size offers increased comfort during long rides and improved stability on uneven surfaces. Larger frames handle better on challenging terrain and can be fine-tuned through adjustments like saddle height and handlebar positioning to enhance fit. If this sound like your style of adventure riding, the correct bike size for you may be larger.

Summary

Finding the perfect gravel bike size is a blend of science and personal preference. By understanding key measurements like height, leg length, stack, reach, and top tube length, you can make informed decisions that enhance your riding experience.

Comparing sizes across brands, fine-tuning your fit, and avoiding common sizing mistakes are crucial steps in this journey. Whether you opt for a smaller or larger size, ensure it aligns with your riding style. Find epci gravel brands such as Cervelo, Trek, Specialized, Cannondale and Argon 18 here at Sigma Sports. 

Gravel Bike Sizing FAQs

Can I use a road bike size calculator or mountain bike sizing guide for gravel bikes?

You can use a road bike size calculator as a starting point, but be aware that gravel bike sizing is influenced by factors such as tyre clearance and geometry differences. For the best fit, it's advisable to consult specific gravel bike sizing guidelines of each gravel bike as different sizes will vary from brand to brand.

How do I know if I should choose a smaller or larger bike size?

To determine whether to choose a smaller or larger bike size, assess your riding style and comfort preferences. Smaller bikes enhance maneuverability, while larger bikes ensure stability and comfort during longer rides.

Why do frame sizes vary between brands?

Much like road bikes, gravel frame sizes vary between brands due to differing design philosophies and geometries, which affect how each brand approaches sizing and fit. This results in distinct frame dimensions that cater to various rider preferences and body types. View all gravel bikes and frames here.