Gravel Bike Frame Explanation

A gravel bike is designed to combine mountain, cyclocross, and road bike features and can be used for adventure and all-terrain riding.The best gravel bikes should be the lightest weight frames, sturdy and versatile. Gravel bikes are prominent for their comfortability due to the wide tires. In this article,we will discuss the gravel bike frames to better choose correct choices.

Gravel Bike Frame

Carbon fiber, aluminum, steel, and titanium are the most used materials on gravel bikes frames.Carbon fiber gravel frames are high performance,light weight and strong and stiff. Carbon fibre frames are comfortable over long distances and very efficient at power transfer. As the carbon fiber manufacture technology has mature,the carbon frame price is more lower and most riders can afford it.

Gravel bike frame geometry has a longer wheelbase, lower bottom bracket, elevated handlebars and slacker headtube angle, which make it more stable on off-road terrain.Most gravel bike manufacturers commonly use small, medium, and large gravel bike frames sizing rather than breaking it down to the gravel bike specs. Upright riding position enhances comfortability, particularly in long rides, and can be used by shorter women and the elderly.

The gravel head tube may not be longer compared to a road bike but slightly elevated than a road bike. This is because the axle-to-crown fork size is long.

The height of the bottom bracket means the vertical distance between the gravel bike wheelbase and the bottom bracket. This is what determines what size gravel bike you need. Some gravel bike models have a low bottom bracket height.Lower bottom bracket can enhance stability and bend while demeriting ground clearance. Taller bottom brackets are ideal for better cleaning of the gruff. However, they are not efficient in terms of stability. The tire size also has an implication on your gravel bike’s bottom bracket height.

Gravel and Cross Bike Size Chart

As stated earlier, a gravel bike has an elevated head tube, unlike a road bike, which is essential for an upright position.

A gravel bicycles sizes chart is one of the most advanced mechanisms for choosing a bicycle. Though gravel bikes and cyclocross bikes are identical in a fitting view, precise numerical dimensions differ. When you measure the centimeters from the bottom bracket center to the top of the safety post clamp, you will identify some variations. Furthermore, the length of the top tube is another differentiating factor.A drop-bar bike can be appropriate in estimating a gravel bike that suits your riding demands. You can ride it and check whether it is compatible with your interests. You can purchase a short road bike which size is less than 56cm and fit them with long stems and vice versa. Nonetheless, this does not apply to gravel bikes. They are customized to fit shorter stems of about 80 to 100mm.

CROSS/GRAVEL BIKES FITTING GUIDE

The most common are 50, 52 and 54 cm gravel bikes. The cyclocross bike frame sizing chart will basically be the same.

Bike Frame Dimensions

Understanding a gravel bike frame sizes chis imperative for most cyclists when choosing a bike. Also, other considerations such as a balanced sitting position, pedaling style, and the right bike size can also play a significant role. But there is more to incorporate than the above.

For instance, two bikes with different dimensions will have varied cycling experiences. This is because the frame differs in size, which may be a critical factor when making your selection.

Familiarizing with bike frame dimensions will enable you to get the spot-on size that you require. Additionally, other bike character traits such as bent, upright, long, and short are projected by frame dimensions.

The frame dimension also matters a lot in handling, steering, and control. This is due to the positioning and slope of the handlebars, among other factors. Additionally, riding does not only involve sitting on a bicycle and riding along. The frame dimensions and alignment determine a lot on comfortability or an endurance gravel bike position.

Based on your preference, you may also feel like adding other components to your bike. Hence, taking a prior look at the frame dimensions can aid in making the right decision. Analyzing the details of the frame dimension and bike’s body can mitigate the risk of injury, fatigue, and performance hurdles due to the bike’s shape.

Head Tube Length and Angle

The head tube length is the distance from the bottom to the top of the bicycle head tube, while the head tube angle is the inclination of the head tube to the road.

This implies that bikes with a short head tube cause the front of the bike to be lower. It causes the cyclist to have a rough time trying to reduce wind and air resistance. On the other hand, bikes with a longer head tube place the front of the bike in an elevated orientation, giving it a wider view. Most racing bikes have a head tube distance of 12 to 15 cm while touring bikes have an approximate head tube length of 20cm.

Little effort is required when steering bikes with an upright head tube angle. This is because they have a fast steering control than models with gentler head tube angles. More power must be incorporated in gentler head tube angles as they have slower steering control.

Despite the control speed, stiffer steering controls are ideal for stability when under high speeds. This mainly applies to bikes with a forward carry and touring bicycles. It is also evident in mountain bikes that require reliable stability while maneuvering in sharp bends and bumpy roads.

Effective Top Tube

It is the horizontal length from the top tube junction to the seat tube. This distance estimates how much space is sitting on the bike. It has become a prominent dimension as more bike manufacturers are adopting the sloping top tubes. It is also one of the three features that determine the length of the front triangle. This includes the length of the stem and height of the saddle seat to approximate how far the arms will extend from the sitting position to reach the handlebars

Stack Height

It is the perpendicular vertical distance measured from the central point of the bottom bracket to the highest position of the center of the head tube. You cannot design a frame without involving such measurements.

It dictates how high the foot distance is on the pedal while the hands are on the handlebars. A greater stack puts the cyclists in a more upright gravel bike body position. It is because the hands will be moved upwards, and the body rises more towards the vertical.

Reach

It is defined as the horizontal distance measured from the bottom bracket center to the highest position of the head tube. Gravel bike reach dictates how far the foot distance will be when on the pedal regarding the position of the hands-on the handlebars.

It has a high relation with stack height in bike geometry dimensions. They both determine the comfortability of the rider when the feet and hands are on the bike. You can identify whether a bike can suit your comfort by gauging reach and stack height even without trying it directly.

You should also note that the riding and comfort position varies from one individual to another based on the size, shape, and length of the arms and legs. Some providers do not disseminate information regarding the reach and stack height distance. Perhaps you can deploy a bike calculator to help you derive such information. You will be required to fill in other dimension details and calculate the stack to reach ratio of a gravel bike.

Different bike models have distinct characters that differentiate a stack and reach ratios. For instance, Racing bikes have a short stack and long reach, while other typical models have a longer stack and shorter reach.

As stack value escalates, the cyclists will experience a more relaxed and upright sitting position. Bikes manufacturers are aiming for long-term comfort design it with a stack value closer to the reach value.

Conversely, when the reach value goes up, the sitting position will be bent, causing the body to stretch. This is mainly designed for racing bikes that target speed increases. Hence, you should be conversant with stack and reach values as it will help you get a bike with an ideal shape and maximum position preference.

Seat Tube Length and Angle

Seat tube length is a special requirement as it mainly functions on cyclists who require a certain height to be able to stand and balance on the bike. It is also necessary that you compare and calculate the stack and reach height. Seat tube length primarily applies to short bikes.

The seat tube angle is the angle of the seat in relation to the horizontal plane. It is measured from behind the seat tube, and it does not significantly impact the experience on the bike. This is because the height of the bike mount can be adjusted. Elevating or lowering the seat will reciprocate longer or shorter distances compared to bicycles with a steeper seat tube angle. You can ignore the size of the seat tube angle and dwell on the seat tube angle number.

Effective Seat Tube Angle

Also known as the Effective Seat Angle (ESA), is the angle from the bottom bracket center to the saddle center while at the appropriate seat height. The right seat height gets determined by a position where your feet can have the lowest pedal position with minimal leg bending.

It dictates the ideal position between the waist and pedals. Saddling the pedals forward and backward may reduce or escalate the effective seat tube angle by up to 3 degrees. The more the ideal sitting position, the smaller the angle becomes. In this consideration, tall cyclists should have an Effective Seat Angle that is steeper than short cyclists while on a similar bike.

Fork Rake/Offset

It is the distance between the vertical line at the center of the wheel and the projected extension of the fork of the surface. It is known as a fork rake in racing bikes and referred to as an offset fork in mountain bikes.

The fork rake is an imaginary line that has similar impacts as the head tube angle. They differ in units as the fork rake is defined in length, and the head tube angle is defined in degrees.

When you increase the length of the fork rake, you will experience faster handling, while vice versa will occur when you shorten it. If you lengthen the fork rake and lower the head tube angle, there will be a similar fork trail length.

Measuring the Dimensions

The following terms are involved in detailed measuring of a bikes dimensions:

C = Center (central point)

T = Top (the very top)

B = Bottom (the very bottom)

I = In (deepest part)

O = Out (outermost part)

The terms can also be combined to enhance more dimensional measurements. For instance, C-C refers to Center to Center, and C to T refers to Center to Top.

Additionally, different calculation techniques may result in different numbers when executing the measurement of dimensions. Mountain bikes are generally measured using inches, while road bikes dimensions are in centimeters.

Some bikes have extensions at the seat tube above the top tube junction, while others use just a seat mast. This may not be easy when measuring and comparing the dimensions.

Another critical variation is between the adult and kid’s bikes. Manufacturers use the frame size to measure. They measure from the center of the crank axle to the top of the seat tube. Conversely, kids’ bikes depend on wheel size rather than the frame.

What Size Frame Gravel Bike Do I Need?

Gravel bikes have recently become popular because they are versatile and beginner-friendly. However, choosing your ideal size can be challenging at first. You need to assess several factors before making your purchase.

Ensure that you are conversant with the critical bike’s measurements. It is straightforward to end up with the wrong bike due to dimensional measurements. This will enable you to choose a frame that boosts your comfortability. Dimensions are also imperative in bike handling, control, and body alignment on the bicycle.

The length from the seat to the pedals and the handlebars should be a significant concern. This is relatively important based on your height and body conformation. Most manufacturers avail such information on the bike, making it easier to identify your ideal gravel frame size.

Xiamen Tour de Cycling is committed to providing high quality, low weight , high strength and high performance carbon fiber gravel bike frames, we can provide hardtail low weight carbon gravel bike frames, as well as lightweight and aerodynamic road bike carbon frames and the endurance MTB bike carbon frames. Please contact us to start your OEM project.

Hope this article can help us more better know the gravel bike frames features and sizes before you purchase.