On Bicycles, and.... what else is there?

Last week I rushed to my bike to catch my morning train and the tire was flat. There wasn't nearly enough time to swap the tube, but there was an old Mavic Open Pro wheel laying there with an old Continental Supersonic 20 mm tire. I grabbed the wheel, inflated it to 100 psi (it held!), put in on my bike and caught the train. I couldn't believe we used to race, let alone train, on these things. Every bump felt like it threatened to cause a pinch flat. Even the speed bumps in the parking lot at work seemed like they'd launch me into ballistic trajectory. Ellis Randonneuring bike, 2011 North American Handbuilt Bike Show (James Huang, CyclingNews ) The improvement in ride quality going from 20 mm to 23 mm tires is profound, and it's even better making the jump from 23 to 25 mm or 26 mm. I love my Michelin Pro 25's, and my Grand Bois Cerf 26's. They're even good for a little fun on the dirt, riding fire roads and smooth hiking trails. But even 26 mm ti...

After the data presented by VeloNews on the effect of going from 23 mm to 25 mm tires, at the same pressure, on vibration reduction (measured with accelerometers: see this post) I was inspired to get fatter tires for the MDR ride (which I described last post). Bicycle Quarterly has published several reviews and tests of the rolling resistance of randonneuring tires, and the Gran Bois tires, "hand-built" by Panaracer in Japan, have always tested well. Jan Heine, the publisher and main contributer to Bicycle Quarterly imports these tires and sells them through his web-based retail business, Compass Cycles , so can be said to have a profit interest in reviewing these tires positively. Neverthless, his reviews are well written and his tests are well documented, so I had good reason to believe him when he said they are supple, have good rolling resistance, and are comfortable. When I saw them for sale in Box Dog Bikes in San Francisco , that sealed the deal. Bicycle Quarte...

Consider half the rider + bike to be a point mass, suspended from the road by a spring, the bike tire. This is a classic spring-mass system . Spring-mass systems naturally resonate at an angular velocity ω₀ = sqrt[κ/M], where κ is the elastic constant of the spring (the ratio of force to displacement), and M is the total mass of the load (the bike + rider in this case). The frequency response z as a function of angular velocity ω is: z(ω) = 1 / [1 - (ω / ω₀)²] To go from angular velocity (radians per second) to frequency (oscillations per second, or Hz) divide by 2π. So well below the resonance, the frequency response is one: when riding over gradual rollers, the tire deflection barely changes. On the other hand, well above resonance, the transmission decreases proportional to the square of the frequency. In actuality, no spring is perfect: there is some energy loss with each oscillation. When this effect is included, the system becomes a "damped" spring-mass system. Whe...