Originally Posted by
Johno59
"The fast guys around here (flat terrain, 27mph average speed for 60 mile group ride) are all on 28mm and all inflating to 60psi. They are full size riders"
One of the reasons pro teams are going lower is that rigid carbon bikes with huge BBs, head tubes and deep rimmed wheels need a softer tire to reduce road shock over 20 odd stages. Your fast friends must top well over 30 mph to get a 27 mph average. The TdF has a 200 plus pelaton and they are slower than your local speedsters and furthermore, nobody on the TdF rides a bike under 10K USD!
No pro team rides on less than 95 on the front and 105 on the back and many considerably higher. In the TT it's 120 psi and many of those riders will not average 27 mph.
At 60 psi I suggest your local speedsters contact every pro team in the world as they will all become very rich men indeed.
On the Paris Roubaix - the Hell of the North - wherein on some sections the cobble stones are so bad that riders carry their road bikes rather than ride over the pave the tire pressures are 85 to 95 psi. They still average 24 mph but those stones are so severe that the possibility that a lower pressure might offer some dividend regards a better average speed would be considered manner from heaven.
Training rides are very frequently faster than races and there's no need to rehearse here the reasons why. Everyone knows this. Races are about getting to the line first and no one cares if today's race was fast. And I have done hundred of two kilometer leadouts above 30mph and never thought I was fast. Fast guys dropped me like a stone.
Let's go back to when pressures were higher. Remember Greg LeMond? The guy could talk. He talked constantly. To everyone. He rode Vittoria CX his entire career, from intermediate to retirement. Those tires were 21.5mm to 22mm. He inflated to 95psi. Except when it rained and then he used 85-90. Almost no one is still using 22mm tires. Larger tires take lower pressures.
Who are the pros you know? I was taught to ride by Jimmy Walthour, Othon Ochsner, Babe VandeVelde, Charlie Yaccino. They were always telling us to use less air. I was one of those who listened at least a little. Glad I did.
Paris-Roubaix is much faster than 24mph and no one carries the bike. No one at P-R is using 85 any longer. If you wanted some insight into how P-R pressures are arrived at instead of something you heard at a bike shop forty years ago you could go to Josh Poertner's blog at Silca and read the way it works now. And the numbers used now. Do your own web search for real P-R speed. Paris-Tours was being done above 27mph in the 1930s. On gravel. On 400gram tubulars. On 47x17.