My first serious adult bike (an entry level Raleigh, circa 1971) had 27 in wheels with gum wall tires that carried 75 psi pressure. I was happy with this “high performance” arrangement until I visited Bud’s Bike Shop while teaching in a summer session in Claremont, California. There I saw (and bought) skin wall tires that became my standard from that time forward.
I soon upgraded my bike and started using 700 cc wheels with presta valves. For many years 23 mm tires, with folding bead, pumped to 120 psi were my normal equipment. This arrangement, I believed, was a nice compromise between high performance and high dependability. Except for the steady rise in price, I was content.
Then I started reading Bicycle Quarterly, edited and published by Jan Heine in Seattle. With an earlier career in racing and continuing active involvement in top-level randonneuring, Jan knew bicycle technology and performance very well, both in the United States and in Europe. He and his cycling friends in Seattle were especially interested in the design and performance of classic European road bikes.
I was surprised by the conclusions they were drawing concerning the effect of tire width and pressure upon performance and comfort. Contrary to conventional wisdom, skinny tires (20 and 23 mm), pumped to pressures well above 120 psi did not contribute to fast times except in highly specialized conditions.
On the open roads where most of us ride, even when racing, wider and softer tires are actually faster. They support their conclusions with carefully documented procedures for timing the performance of tires of various sizes and types by well-known manufacturers.
As a result of their studies, I changed how I equip my bikes. On my classic Mercian, which I unwisely modified fifteen years ago, the largest I can carry are 25 mm. On my Waterford winter bike, I use 32 mm tires, and on my Davidson I am currently riding 28 mm but have been thinking of changing to 30 or 32.
The new issue of Bicycle Quarterly (Spring 2013) updates the studies that the Seattle group has been doing. It contains ten articles on the general topic of tire performance. Some of them revise and republish earlier reports. The writers compare clinchers and tubulars, the effect of tread on speed, the comparative performance of specific tires on smooth vs. rough roads, and the effect of “drop” on performance.
Although I do not fully understand the technical material that is included in some of the entries, I come away with four conclusions.
First, there are measurable differences in performance of tires related to materials out of which they are made, their design, their weight, and the pressure they carry. The combination of these factors interacts with road surfaces so that some tires are measurably faster under some circumstances than under others.
Second, for most cyclists the variations are hard to discern under normal cycling conditions. Several of the essays in this issue carry statements similar to this paragraph from “Choosing the Correct Tire Pressure.”
“Fortunately, tire pressure makes only a small difference in tire performance. It is far more important to choose your tires well. Once you have mounted supple high-performance tires on your bike, then you don’t need to worry much about pressure” (p. 44).
Third, several factors affect how fast cyclists can ride and how long they can stay in the saddle. At this stage in my cycling career, the benefits of wider and softer tires, light weight and supple in design, are increasingly persuasive.
Fourth, tires with these characteristics are also reliable on the road. Of course, flats are always possible given the character of streets and highways, but tires that combine comfort and performance are probably more resistant to punctures than the skinny, high-pressure tires I used to ride.
I want to bicycle in carefree fashion, which means, in part, that I don’t want to worry about my tires. Even checking pressure is a bother. That’s why I like the way Jan concludes one of his essays. There are no “hard and fast rules,” he writes.
“On my own bike, the tire pressure changes over time, because I only inflate my tires when the pressure obviously has become too low. As it turns out, that seems to put me right into the sweet spot of tire pressure” (p. 44).