Yes, I fully understand the idea that with a narrower tire can take more pressure (and has to in order to avoid snakebite pucnctures). But no pun intended, high pressure is over rated. Rolling resistance increases at a certain point as pressure increases because of the washboard effect. And it all depends on road surface.
Everything is a tradeoff - and this can all be stated mathematically. But the basic point is that the optimum for most non-race long distance applications is a good bit wider than today's norms. I learned this first hand years ago when I started using Clement Del Mundos instead of Clement Crits and speed on long rides went up as slight (if any) performance declines from weight/aero/rolling resistance changes (from lower pressure) were more than compensated for by a dramatic decline in fatique from time on the bike.
In fact, for most folks, a 650b tire with its dramatic comfort gains is probably the best all around tire. On short fast rides, I've discovered that my times are nearly identical to my times on skinny tires. But the comfort increase is dramatic. Plus, the comfort gains for long distance event rides are simply staggering.
For a long time I was reluctant to embrace the 650b idea. I didn't believe Jan Heine when he told me that his extra long distance rides were faster on 650b. I was certain that a fast 700c would be quicker. But then I put a 650b machine on the road and the way they roll simply blew me away. I could go for a spin on the 650b machine, than hop on the narrow tire tubluar machine and the skinny tires just feel slow. They feel like they are being constantly held up by road vibration while the wider tire just rolls on over everything.
Now folks ask - so why don't racers use wider tires? Because in a race, acceleration is vitally important. Also, as you go faster, as stated elsewhere, aerodynamics play a greater roll. A fat tire has an aerodynamic dissadvantage that grows much more significant at higher speed.
This wide tire thing seems to create controversy since it is counter intuitive to most folks. A few years back, Garret Lai was editor of Bicycling and he wrote a piece on this topic after I pointed out to him that the magazine's tech writer botched the concept in an earlier issue. And I learned about the virtues of wide tires when Matt Wiebe, tech editor of Bicycle Retailer and Industry news, said to me "but Mike, of course you know that wide tires have less rolling resitance than narrow ones."
In time, I'm convinced the industry will discover this and capitalize on it. And when it does, the idea of what constitues the typical high-performance recreational road bike will be change.
Mike Kone in Boulder CO
> email@example.com wrote:
\r?\n> >".....wide tires overall are likely to be faster than skinny tires which have
\r?\n> HIGHER rolling resistance).
\r?\n> You forget the important words "at the same pressure."
\r?\n> At a given weight and pressure the contact patch is going to be pretty
\r?\n> much the same area regardless of tire size, the wider tire has the
\r?\n> rolling resistance advantage as the contact patch while the of the same
\r?\n> area is shorter i.e. the flat spot is not as long.
\r?\n> Due to structural reasons skinner tires generally can take more pressure
\r?\n> which creates a smaller contact patch which can quickly overcomes the
\r?\n> advantage of the wider tire.
\r?\n> It is all a compromise, there is I believe a sweet spot or zone
\r?\n> depending on the rider, the road conditions and the weight carried.
\r?\n> Cobbles on a 21mm tire at 140 psi or a smooth steep climb on a 38mm
\r?\n> tire at 50psi both would tire (pun not intended) me out pretty quickly
\r?\n> and the reverse situation would be a definite improvement.
\r?\n> That said, it seems quite obvious to me that 1 1/4" or 32mm is THE
\r?\n> perfect tire width, now how about that diameter I'm thinking 597mm. ;-)
\r?\n> Marcus Coles
\r?\n> London, Ontario, Canada