Tyre pressure is something that affects us all, it can influence performance as well as comfort on the bike and it can be difficult to get the pressure right.
The subject itself is often the talk of club riders' cafe stops - along with the benefits of compression socks and what the runner up of the 2003 Tour de France is doing now - but no longer will the mysteries of tyre pressure be kept from mere mortals!
This in-depth guide will explain tyre pressure, what it's measured in, the effects it has and how to choose the right one for you. No pressure.
What IS Tyre Pressure?
Tyre pressure is basically the amount of air present inside the tyre at any one point, this fills the inner tube and consequently makes the tyre firm. The more pressure you put in, the more air you are putting into the tyre which makes the tyre firmer and the rider stiffer.
It is measured in PSI or 'pounds per square inch' which in real terms relates to force generated by a one-pound force applied to an area of one square inch. This is what many pressure gauges on pumps focus on, usually with a scale running from 20-120 PSI. There may also be a BAR/Atmosphere reading on the gauge which is just another way of measuring pressure, albbeit slightly older. 1 BAR roughly equates to ~14 PSI.
How Does It Affect Performance?
At the top level of bike racing, tyre pressure can be the difference between winning and losing. But in reality you might not notice too much difference in your performance on a day to day basis unless you do compete.
The tyre pressure influences the amount of tyre in contact with the road - a lower pressure means more surface area is in contact with the road, ergo there is more rolling resistance and you will go slower, even if it is only marginally.
That doesn't mean you have to pump your tyres up until they're ready to burst though - it is recommended that in wet weather or on poor road conditions you ride with a lower pressure. This is because punctures are less likely at a lower pressure, even with the increased surface area.
The lower pressure means the tyre wall isn't as tight against the tube as with higher pressures, reducing the potential for pinch-flats and for punctures related to poor road surface. For context, the professionals who race in the spring classics like the Tour of Flanders and Paris-Roubaix often ride on lower pressures do to inclement weather and poor road surfaces.
How Else Does It Affect Me?
Tyre pressure doesn't only affect the performance of the bike, it can also have a significant effect on the ride quality and your comfort when on the bike.
Tyre pressure that's too high will result in a stiffer ride which can be problematic if you're riding on poor quality roads. Higher pressure means harder tyres, and harder tyres absorb less which will magnify every bump and dip you roll through. This also increases the potential for punctures as we have covered above.
Tyre pressure that is too low can result in a bumpier ride which may lead to difficulty controlling the bike if the roads are particularly bad. Too low pressure can also result in a bumpier ride as the wheel rim may begin to make contact with the road through the tyre on the bumps. This can be disastrous, especially if you are running a premium wheelset like our Cero RC45s.
So What's The Correct Pressure?
The correct tyre pressure will be unique for every person depending on what makes their ride comfortable - some ride low, some high but the majority of riders keep it inbetween the two.
One the tyre walls of your bike there will be a minimum and maximum recommendation for inflation - these should never be exceeded as to do so would be dangerous and would compromise the integrity of the tyre and lead to potential blowout.
Many tyre brands publish recommended pressures based on tyre size and width and body weight, see below for Schwalbe's recommended pressures.
The best thing you can do is find a pressure that's creates a comfortable ride that is within the min/max limits - for the majority of cyclists this usually hovers between 80-100 PSI but there is no wrong answer here as long as you're within those limits.