What is the optimal Gravel Bike tire pressure ?
Did you know that the easiest and free way to change bicycle performance is to adjust the air pressure of the bicycle tires?
Changing the air pressure on the bicycle tires will probably give a more pronounced difference in the character of the bike than upgrading the Boost hub to SuperBoost. Regulating air / wind pressure on bicycle tires is sometimes overlooked and underestimated. Even though this method is the easiest and cheapest, even free to do, which can have a significant impact on the bicycle. Since these two bicycle tires are the parts that are in contact with the road surface, remove any other bicycle components (except for falls).
“The air pressure on the bicycle tires will make a bigger difference to the performance of the bike than most bike technologies we might buy”
Effect of Air Pressure
The most important thing that we must understand is how the air pressure on the bicycle tires can affect the bicycle and bicycle performance. Low, normal, high air pressure will make a bicycle different.1
Under inflation (low air pressure), over inflation (high air pressure), correct inflation (normal air pressure) makes a different tire shape, which we can sometimes see with our eyes.
Unsuitable air pressure can affect the following:
Higher air pressure will result in lower rolling resistance and lower temperatures, because the tires will be stiffer or harder to deform. So we think that by increasing the wind pressure, the bike will be faster. But that’s not always the case, the above statement only applies when cycling on smooth roads and rigid bikes (without suspension). For racing bikes on smooth asphalt roads, increasing the tire pressure will make the bike go faster, of course, with certain limitations.
For racing bikes with maximum air pressure on uneven roads, it will make the bike bounce, because the tires do not have the ability to absorb vibrations and shocks.
Mountain bikes (hardtail and softail) on flat or uneven roads are affected by road vibration and loss of power due to suspension will affect bicycle speed.
For cars or motorbikes, tires with low air pressure will make fuel consumption higher or run out faster. The same applies to bicycles, tires with lower air pressure will drain more energy. Because with low pressure it is more flexible and easily changes shape when the wheel rotates. Some of the power from the pedal will be absorbed by the shape of the tire that is loose or not stiff.
Traction and control
Traction or grip is the friction of the tire against the road surface. The more the surface of the tire sticks to the road surface, the more it will bite against the road.
When cornering, generally the bicycle will tilt more in the direction of the turn, the tire will also change its shape, and make one side of the tire more in contact with the surface. On low pressure tires, the air will be compressed to the opposite side, thus making the tread and tire knobs deeper and not biting the road surface.
Same when we do the brakes, what we need is as much rubber tires as possible biting the road so that the wheels quickly stop.
Air pressure that is too high will also cause less tread to touch the road and a stiff tire, which can result in tire slip.2
Top 10 Gravel Bike
Bicycle tires are like shoes, soft shoes are more comfortable for running than hard shoes. Low-pressure bicycle tires absorb shocks and vibrations from the surface, while also absorbing some of the force of the pedal. The tough tires transmit vibrations to the bike, bicycle suspension and cyclist body.
Air pressure on tires under normal conditions recommends that the tire tread in contact with the road surface is under even pressure on the more sides of the tire (center and left-right). Excessive air pressure will make the middle side get more pressure, while the less air pressure will make both sides (left-right) get the greater pressure.
In the long run, this will wear out (bald) tires with an unbalanced composition. And of course a tire with high or low air pressure will make the tire age wear out faster.
Ideal air pressure
There is no magic number that says tire pressure has to be this or that. Many factors influence the optimum air pressure. The air pressure suitable for one person must be different from the air pressure for another. But there is a certain sweet spot that we can look for to get the air pressure according to what we want.
Before we look at how to get the ideal tire pressure, let’s first look at what are the factors that influence to get the ideal tire pressure.
Several things to consider for ideal air pressure
based on articles from The Geek Cyclist 3 about Gravel Bike Tire Pressure Guidelines
It doesn’t take a physicist to explain that a cyclist’s weight, luggage and bicycle itself will affect the pressure on the bicycle tires. The heavier the load that the bicycle tire is holding, the higher the air pressure in it. The air pressure needs to be regulated so that when the tire receives a load (which is still within the capacity of the bicycle), it will not make the bicycle tire run aground. As a result, the heavier the cyclist, the higher the air pressure. For example, a cyclist with a weight of 75 kg cycling with an air pressure of 30 psi, if he is carrying a load of 10 kg then it is necessary to add 3-25 psi to the tire pressure.
Unlike a car whose passenger weight is much less than the weight of a car, for a bicycle, the weight of the passengers and luggage is greater than that of the bicycle, which makes the weight of the cyclist a major factor. That’s why measuring tire pressure for bicycles is a little different and personal.
For the same bicycle tire diameter, the wider the bicycle tire, the greater the volume of air that can enter in it. So that to get the same pressure, wide and narrow tires require different volumes.
Wide tires can fill a lot of air, making them more comfortable and bite when carried at a slightly lower air pressure, such as mountain bike tires.
But on skinny race bike tires, carrying it at low air pressure is a big risk of aground.
Terrain and cycling area
We can take into account the tire volume and bicycle load. But not with the cycling area, especially offroad, we can enter into new, strange, and never predicted areas. Sometimes when we enter a different area of length, we feel the bike is no longer as comfortable as before and need to make adjustments.
For example, when entering a bumpy area, the bicycle feels like it has been hit too hard, maybe the air pressure is too low. Or when entering a cornering highway, the bike feels like it often slips and spins, maybe the air pressure is too high.
Tubeless tires that do not use inner tubes allow for use with lower air pressure. Because you don’t have to worry about the inner tube being pinched and torn. Likewise, the rolling resistance on tubeless tires is lower than tires with inner tires. So that the ideal air pressure between tubeless tires and non-tubeless tires will not be the same.
Cycling style also needs to be considered when regulating air pressure. Are you a person who likes to climb and jump over embankments, or a person who looks for smooth passage between rocks or a person who crushes anything in front of him?
Tire Structure / Material
The construction or material of a bicycle tire can also affect the ideal pressure. If you replace a bicycle tire with a different type, your ideal air pressure might change.
Bicycle tires with a higher TPI (threads per inch) are usually more flexible than tires with a lower TPI. Rubber material, puncture protection, makes different tire characteristics at the same pressure, Schwalbe bicycle tires and Maxxis bicycle tires have their own formula for the materials used. This is also the reason why the maximum pressure and ideal pressure between tire makes and models vary.
source: The Pros Closet 4
Recommended Gravel bicycle tire air pressure
If we look at the side of a bicycle tire, there will be a label for the size of the bicycle tire and also the maximum air pressure in bar or psi units. 1 bar = 14.5 psi (pound square inch).
Max pressure means the maximum air pressure that the tire can withstand, the “safe” limit of the tire manufacturer, which if a few psi is passed it still works, but if it gets too many tires, it will bend or pop.
Find The Optimal Gravel Bike Tyre Pressure
These pressures might not be perfect for everyone but should provide you with a good guide to begin your own obsession with riding gravel and tyre pressures.
A quick note, for anyone who has rims narrower than 21mm, simply add a couple of extra psi to the recommendations given for 21mm rims.5
Gravel Bike Tire Pressure Chart
GRAVEL BIKE TYRE PRESSURE FOR 21MM RIMS
GRAVEL BIKE TYRE PRESSURE FOR 23MM RIMS
GRAVEL BIKE TYRE PRESSURE FOR 25MM RIMS
GRAVEL BIKE TYRE PRESSURE FOR 27MM RIMS
Tire Drop method
The tire drop method was created by Frank Berto, who stated that the ideal tire pressure is 15% tire drop or the tire decreases by around 15% when it is climbed from the tire position without a load. In this way, the tires will never keep the tires from being too low or too high. The method is claimed to get a comfortable tire pressure value but also a strong grip on the road surface.
It’s a bit difficult to measure the drop, but it can also be seen from the shape and curvature of the tire when it is pressed under pressure. In the depressed 15% position, the tire is still rounder at the bottom.
Or following the graph from Frank Berto 6, he did a lot of experiments, and the results were plotted in a graph that we can use.
The weight on the chart is the weight of the wheels, not the weight of the bike. Each wheel must be weighed against the load condition, rear tire and front tire. Then the weight is plotted on a graph according to the tire diameter, and the ideal pressure (on the left) is obtained for each tire.
High and Low Tire Pressure
The general guidelines for tire pressure are usually the most appropriate and represent the general conditions. But for a more personal setting, we can increase or decrease the tire pressure. Things that tend to be obtained when increasing tire pressure:
High air pressure
When we increase the air pressure in the tires, this is what happens:
+ stable, because the tires are stiffer and do not fold
+ safer from leaks, it is more difficult to pinch the inner tube
– reduced grip
– less comfortable because the tires do not absorb vibrations
– on uneven roads it will bounce off
Low air pressure
When we increase the air pressure in the tires, this is what happens:
+ stronger grip
+ on uneven roads the bike can go faster
+ more comfortable
– less stable
– it is easier for the inner tube to leak
– more energy drained
From changes in character due to changes in air pressure, we should be able to estimate the ideal pressure for various conditions, such as air pressure for rough, muddy, muddy, dry roads, and so on.
Front and rear tire air pressure
The pressure received by the front and rear tires is of course different. The rear tires receive more pressure and work more as a propulsion wheel. Therefore we have to set the rear tire air pressure higher than the front tire air pressure.
The load distribution of the rear tires and the front tires themselves can vary. For mountain bikes, the ratio is around 40%: 60% (front: rear). For race bikes where the cyclist is bent more forward, the ratio can be up to 45%: 65%. For a more upright bicycle position such as folding bikes, urban bicycles, buses up to 30: 70%.
The rule of thumb that is commonly used is that the front tire has 10% lower pressure than the rear tire. Whereas for bicycles that carry a lot of weight at the back and a cycling position that is always upright, it can reduce the front tire pressure by up to 20% from the rear tire.
The recommended value above can be used for the rear tire, and the front tire adjusts from that value.
Best Tire Pressure
Recommended values are just general guidelines, as we mentioned earlier, there is a certain best value (sweet spot) for each person for various activities. Some are concerned with speed, some are concerned with comfort, etc., and cannot get it all, there are factors that must be reduced to increase other factors.
Cycling experience is very important, and repeated experiments must be done to get the most ideal score. Air pressure is calculated with numbers and tools, not everyone can calculate with the thumb pressure (pressing the tires). For pressures above 30 psi (2 bar), the strength of the thumb is usually not good enough to estimate the value of air pressure.
Can use an air pressure gauge meter (air pressure gauge), a pump or compressor that has a gauge. Start from high pressure, and carry and ride the area to be calculated, reducing the air pressure for each lap made. By comparing several air pressures, we should be able to deduce or narrow the range of air pressure which is best.
Sometimes we want to know the tire air pressure without tools, to see if it is overloaded (too high) or underload (too low). The easiest way to estimate air pressure without a tool is to look at the tread of a bicycle tire. Take the bicycle to a wet or watery area or flush the tires with water, then cycle to a dry area. From the remaining tracks, we can see the condition of the tire tread, for tires with normal pressure, the tread will be printed flatter from the left to the right.
Pump up bicycle tires
For cyclists, pumping tires or filling up bicycle tires must be done regularly. Air is a gas that can expand and shrink, and move from high pressure to low pressure. And bicycle tires, whether tubed or tubeless, are not 100% impermeable. In the unused condition, every month the tire will lose 1 psi. Likewise with temperature, every 12% change in temperature will change the air pressure by 2%. If the temperature gets hotter, the air pressure in the tires will increase, and vice versa. Schrader and Presta valve valves have little effect on loss of air pressure.
So used or not used, the air pressure in the tires will change accordingly. To get the same performance, we must regularly check the pressure and pump our bicycle tires.
These are good standards to go by and I hope it helps you out to run a more confidant tire pressure on your gravel bike.
Bicycle tire air pressure calculator
This calculator was created by Schwalbe, is more focused on various mountain bike activities, and uses the terms used for the tire components of Schwalbe bicycles.
Wind pressure calculator for racing bikes, we can factor in duration, road conditions and weather to estimate the ideal air pressure.
A simple but efficient calculation, incorporating the weight and load distribution factors of the bicycle to get the front and rear tire air pressure.