I recently inflated the tyres on my bike (23 millimetres) to 7 bar before the start of an RTF. My fellow cyclist nagged me to pressurise the tyres properly, otherwise they wouldn't roll properly. Was he right?
Christian Hein, Pfaffenhofen
Not really. There are a lot of half-truths circulating on this subject, even among experienced cyclists. Tyre pressure regulates the compromise between the lowest possible rolling resistance, riding comfort, puncture resistance and tyre grip. The higher the pressure, the faster the tyre rolls on a flat road - your fellow cyclist is right on this point. However, on uneven, rough surfaces - actually the normal case on most roads - too high a pressure means that the tyre no longer rolls smoothly, grip on bends or when braking is reduced and comfort decreases. The pressure level depends on tyre width and rider weight. For 23 millimetre wide folding or clincher tyres, a pressure at the upper limit of the value specified by the tyre manufacturer (usually 8 to 9 bar) is recommended for heavy riders. Riders weighing around 75 kilos achieve good tyre performance at around 7 bar. Lighter riders can ride such tyres at 6 bar or less.
