Quote:
Originally Posted by spoonrobot
The fact that brings us all back down to Earth: at what point in time would you be able to make this statement and have it be a broadly true statement?
I know it wasn't true in the recent past because I went out and bought the fastest 700cx35 tires I could find, and they were significantly slower than regular high-level 700cx23 tires.
So, it apparently wasn't true in 2014, or 2004, or 1994. So 2019? 2021?
Is it broadly true today?
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It is often the case that a truth can not be summed up in a simple statement that covers all conditions, but instead a true statement has many conditions, presumptions, and assumptions for it to be true. In the case of the rolling resistance of 32mm tires vs. 23mm tires, it depends on many variables, including surface conditions. pressures, loads, construction and materials, etc.
So, if we hold the environment conditions constant, including a road that is representative of typical paved roads, and loads typical of single bicycles, and pressures typical to those used by the average cyclist, can we still say that a typical 32mm tire rolls faster than a typical 23mm tire? Maybe, maybe not. In the past, it was assumed that someone who bought a 23mm tire preferred low weight and rolling resistance over durability and robustness, and that they would be riding on smooth surfaces so needed little tread depth, so 23mm tires were typically built with flexible high thread count casings and thin treads. At the same time, it was assumed that someone who bought a 32mm tire preferred durability and longevity over weight and rolling resistance, and would be riding on looser surfaces, so 32mm tires were typically made with thick, stiff tread cords and deep high durometer treads with grooves and knobs for traction on loose surfaces. This meant that in the past, a typical 32mm tire did not roll as well as a 23m tire, as least on smooth pavement.
But what of today? With the acceptance of wider tires by people looking for performance, manufacturers are making 32mm tires with flexible high thread count casings and thin treads. And these tires can indeed roll with less resistance than otherwise similar 23mm tires in many cases.