Although most of the time, the recommended tyre pressures are indicated on the side of your road bike tyres, those do show some general guidelines.
It generally indicates the maximum permissible pressure and sometimes the minimum. But this should be adapted according to the type of cycling, the kind of road and, especially, the weight of the cyclist.
Many people just inflate their tyres as much as possible, thinking that this will only improve performance. Error. If you over-inflate, in relation to your weight, the performance of your tyres will suffer, particularly on bad or bumpy roads, when the tyre, rather than twisting out of shape, will tend to bounce on the tarmac. This causes significant losses in terms of energy transmission.
Adapting your tyre pressure to suit your cycling
Mountain bikers have long understood the importance of varying pressure according to the type of terrain. They alter their pressure, and even their tyres, to suit each surface, whether rocky, slippery or muddy terrain etc.
Road conditions are less variable
Only track cyclists are advised to inflate their tyres to very high pressures (10 bars or even more) but in their case, the cycling surface is normally in perfect condition.
On the road, conditions are a lot less variable.
10% of your weight
In general, the recommended pressure is 10% of a cyclist’s weight. In general, this rule works rather well although when it comes to very light or heavy riders, there are upper and lower limits that should not be exceeded.
But there’s little point over-inflating your tyres if you’re 80 kg or above. Even for a cyclist weighing 100 kg, you are recommended not to exceed 8.5 bars.
For lighter cyclists – weighing 50 kg or less – the lower limit of 6 bars is the minimum acceptable pressure; you are advised not to go below this otherwise you will risk puncturing the inner tube if you hit a pothole.
These values are only intended as a guide and should be adapted, as far as possible, to suit each individual rider. You can vary the recommended pressures slightly (+/- 0.5 bar) depending on the type of cycling surface and your own particular preferences.
But as you’ll have gathered, you’ll gain nothing in terms of performance by inflating your tyres to more than 9 bars, quite the contrary in fact. You’ll just get a bit of a bad back!
I weigh 73 kg and inflate my back tyre to a maximum of 7 bars and generally 6.5 bars for the front. This is quite adequate in most cases and I only have the average number of punctures (one a year).
All the pressures given are for standard 700 x 23 tyres. For wider 700 x 25 tyres, you could easily reduce the pressure by 0.5 bars, in relation to the graph.
Advice for riding cobbles
When racing on cobbles, professional cyclists usually use 28 mm tubular tyres for greater comfort.
For example, when he won the Paris-Roubaix, Fabian Cancellara used 27 mm tubular tyres inflated to a pressure of 5.5 bars at the front and only 6 bars at the rear. And when you think that he weighs 81 kg and had an average cycling speed of 45km/h.
If you want to inflate your tyres to similar pressures, and with relative ease, you can’t depend on your hand pump which is best kept for roadside repairs, in the event of a puncture.
A high-quality foot pump with a gauge will allow you to inflate your tyres to a pressure of 7 to 8 bars with both accuracy and ease.