63rickert

I run equal pressure front and rear. Sometimes all weight is on front, sometimes all weight is on rear. On hard braking a bike develops g-forces and weight, or force, on front wheel is more than the total static weight of bike and rider. This is all included in the engineering assumptions incorporated in the Berto charts.

By seat of pants the pressures picked over the years were about 10 psi over Berto and pretty consistently 10psi over. Took a long time to believe chart and start adjusting down. Still always works. 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. I'm not going that low but it works. And again, unless you spent money for a reference pressure gauge you don't know that precisely what your pressure is. Day to day your gauge is probably giving consistent information that means something and you can work with. But it is probably not same as my gauge.

Only bike that gets unequal pressure is the DL-1, which has 25/75 weight distribution. Maybe 20/80 when the saddlebag is heavy. Sticking to the chart would give silly numbers. The chart has no enforcement clauses and no penalties.

jackbombay

Ahh, I did decide that the front needed some more air, good to know about the 40/60 45/55, thanks!

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.

63rickert

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.

Johno59

I'm fat and old-fashioned and it is a given that when I strive to get 40 km in an hour, having rock hard tires is not the smart way. Obviously feeling a dead badgers whisker on the road inspires me to suck up the pain but such hard tires are far from clever. However can you tell me what teams ride 60 psi tires training/racing and AVERAGE 27 mph coz I am desperate for a softer ride.

Johno59

The PR cobbles are horrendous, Unlike a normal urban cobbled pavement many of the rural pave on the Hell of the North have an inch of space between individual stones.

Team-by-team breakdown:

Omega Pharma-Quick Step
Wheels: Zipp 303 Firecrest
Tire: FMB cotton casing
Size: 27mm
Measured size: 28.2mm
Pressure front: 59.5 psi Boonen, 58 psi Chavanel (58 psi or less in the rain)
Pressure rear: 62.4 psi Boonen, 59.5 psi Chavanel
Sealant: no

Movistar
Wheels: Campagnolo Hyperon
Tire: Continental Competition
Size: 27mm
Measured size: 27.8mm
Pressure front: 85 psi
Pressure rear: 87 psi
Sealant: yes

Liquigas-Cannondale
Wheels: Mavic M40
Tire: no markings, looked like Veloflex
Size: ?
Measured size: 25.1mm
Pressure front: secret
Pressure rear: secret
Sealant: no

FDJ-BigMat
Wheels: Shimano C35
Tire: Hutchinson labeled Dugast
Size: 27 and 30mm
Measured size: 28.9mm (for the 27mm)
Pressure front: 72.5 psi (Rollin)
Pressure rear: 80 psi (Rollin)
Sealant: yes

Europcar
Wheels: Campagnolo Bora
Tire: Hutchinson (FMB or Dugast)
Size: no marking
Measured size: 29.2mm
Pressure front: 72.5 psi
Pressure rear: 80 psi
Sealant: no, but they did last year

Lotto-Belisol
Wheels: Campagnolo Record hubs with Ambrosio Nemesis rims
Tire: Continental Competition
Size: 27mm
Measured size: 27.2mm
Pressure front: 67-72 psi
Pressure rear: 70-80 psi
Sealant: no

Saxo Bank
Wheels: Zipp 303 Firecrest
Tire: Specialized (FMB Paris Roubaix cotton casing)
Size: 27mm
Measured size: 28.1mm
Pressure front: secret
Pressure rear: secret
Sealant: yes

Radioshack-Nissan
Wheels: Bontrager
Tire: FMB Paris Roubaix
Size: 27mm
Measured size: 28.3mm
Pressure front: 80 psi
Pressure rear: 87 psi
Sealant: no

Garmin-Barracuda
Wheels: Mavic M40
Tire: “French handmade provided by Mavic” FMB
Size: 27mm
Measured size: 28.5
Pressure front: 62.5 psi
Pressure rear: 72 psi
Sealant: no

GreenEdge
Wheels: Shimano C35/DA hub w/ Ambrosio “PRO” rim
Tire: Continental Competition
Size: 25 and 28mm
Measured size: 24.8 and 28.5mm
Pressure front: 76.9 psi
Pressure rear: 82.7 psi
Sealant: no; “We were told by Continental that it doesn’t work. The sealant only hits the top of the tread, not the sides. It doesn’t stick to the sidewall of the tires and that’s where the tires pinch at Roubaix,” said mechanic Craig Geater.

Sky
Wheels: Shimano C35
Tire: FMB Paris Roubaix
Size: 27mm
Measured size: 27.9mm
Pressure front: 67.4 psi
Pressure rear: 74.0 psi
Sealant: yes; “If it helps the riders get to the end of a sector, maybe it doesn’t stop a puncture, but it does slow it down. If so, it’s worth a shot,” said Richard Lambert, one of Sky’s mechanics.

Katusha
Wheels: Mavic M40/Cosmic Carbone Ultimate/aluminum rim mix
Tire: Mavic SSC-labeled Challenge Parigi-Roubaix
Size: 27mm
Measured size: 27.9mm
Pressure front: less than 87 psi
Pressure rear: less than 87 psi
Sealant: yes, liquid latex

Cofidis
Wheels: American Classic Carbon 38
Tire: Vittoria Corsa CX
Size: 25mm
Measured size: 25.1mm
Pressure front: 72.5 psi
Pressure rear: 80 psi
Sealant: no

Saur-Sojasun
Wheels: “Corima” Dura-Ace or Ultegra hubs on Ambrosio Nemesis rims
Tire: Panaracer-labeled Veloflex
Size: 27mm
Measured size: 26.0mm
Pressure front: 72 psi
Pressure rear: 80 psi
Sealant: no

Lampre-ISD
Wheels: Campagnolo Record hubs with Ambrosio rims
Tire: Vittoria Pavé
Size: 27mm
Measured size: 26.0mm
Pressure front: 80 psi
Pressure rear: 87 psi
Sealant: yes, put in on race morning (Vittoria Pit Stop spotted in the team truck)

Ag2r La Mondiale
Wheels: Reynolds 32
Tire: Michelin tubulars (prototype rear)
Size: no markings
Measured size: 26.0mm front/24.7mm rear
Pressure front: 65 psi
Pressure rear: 71 psi
Sealant: yes

The rocks on the PR are IMHO the ultimate case for soft tires.
I still can't see the 60 psi of your local black-top riding speedsters.

RobbieTunes

Really cool info. DA35's are some of the best all-around wheels I've seen. The C24, as well, since I'm not running pro wattage.

For me, It would be a toss-up between the DA35 and the 303 Firecrest, for me. If they'd lace the (ball bearing) DA9000 hubs to Zipp 303's, I'm just as happy, albeit "heavier."

I wonder how the wheels/tires look after a day of that pounding.

63rickert

An error above. Working from memory. Gustave Danneels won the 1936 Paris-Tours at an average speed of 25.8. He was the one who reported he had done nearly all of the race in his middle gear of 47x17. Also remember that this is before large fields, much less well-organized teams. This speed done in a very small group and concluding with a long solo break. Paris-Tours course chosen for the flat terrain and good surfaces, in '36 a good road was often simply well maintained gravel. Jules Rossi did Tours in '38 at an average 26.2. In 1948 King Rik van Steenbergen completed Paris-Roubaix at an average 27.1. At this years Vuelta, stage 17, Philippe Gilbert completed an over 200km stage at an average of 31.5.

Roubaix has the famous pavé, it is only 50 or so kilometers. The other 210 km are fast and flat. The riders do not change wheels for the pavé. Finish at a velodrome. The tires are fast at same pressure as is used for the cobbles.

The chart posted above is quite interesting. Note FDJ team riding 27mm tires with real measure of 28.9. And also using 30mm tires. What is real measure on those? Sagan has been reported to use 32mm tires. Most of the pressures noted are simply 4, 5, or 6 bar badly converted to psi. "Secret" is the best answer. "Less than" is another good one. And all pressures will be much lower 6 hours later.

The locals using 60psi are not as lightweight as the pro peloton. Not close. I wouldn't do it. And am much too old to still play above 50kph. They do it. It is possible.

Johno59

A good rule of thumb for those like me who are fat is add 2 psi to your tire for every 5 kgs over what a 70 kg rider would have (or better still lose weight). A heavier rider must have greater tire pressure not less.

Johno59

The Tour of Flanders is even harder on tires than the PR. Here is one guys take on tire pressure -
"The tyre pressure that you are using is obviously slightly dependent on your weight and the tyres that you are using. I weigh 68kg and was riding 25mm Continental Grand Prix 4 Seasons clinchers. I rode with 85psi pressure, which is lower than the pros but therefore more comfortable on the cobbles. Sagan for example rides a 105/109 psi set up, with 28mm tubulars. Wout van Aert rode 28 mm Vittoria Corsa tubulars with a 97psi front and back. Deceuninck-Quick Step rode the 2019 Tour of Flanders using 26mm Specialized Hell of the North tubulars. "
The Tour of Flanders makes the PR feel like a velodrome tire-wise

ThermionicScott 

I thought I recognized this article. It's from 2012, so the big story at the time was pros running less than 100 psi!

Note that most of the riders were still on 25-27mm tires. Now that 30-32mm tires are more accepted, I'm sure more of them are pumping up in the 60s.

Johno59

"Deceuninck-Quick Step rode the 2019 Tour of Flanders using 26mm Specialized Hell of the North tubulars. "
Yeah

Johno59

My lack of respect for the Force has disturbed a greater entity.
I punctured yesterday morning, actually ruptured is a better description.
Swerved a monster pot-hole in the dark, caught a large piece of flint on its perifery and sliced the wall of my near new 26mm Conti 4 seasons clincher and tube. Both a right off.
My heresy in engaging with the shadows lurking on the dark side of 100 psi has been duly punished by the Force.
My hand pump is good for 60 - 70 psi and once I was on my way the difference was blatantly obvious. I'm sorry but a 200 lb total weight on 60 to 70 psi is just not happening for me. OK maybe for a 140 lb rider it works (when I was a 140 lb rider it still didn't but hey, that was then) but yesterday it was not even close.
As you go up thru 20 mph the extra load on your cranks is blindingly obvious. Perhaps when you pass beyond 25 mph you go thru an event horizon and the flat spot where rubber hits the road decreases and roundness and speed propel you onwards and upwards to a better place, but I have my doubts.
This morning I used my track pump and put 105 psi in both and flew down the road.

Johno59

When we talk about softer tires(70-90 psi) it helps to remember these are the roads they are designed for. I wouldn't travel a single yard over these type of roads in a entire 7000 mile year. 30 miles on cobbles at 25 mph in a single day! on a road bike - the exception proves the rule.

Rollfast

I'm not the goo putter-inner, I just own a Shelby, J. C. Higgins, 3 Schwinns and 3 Rollfasts, nothing that shifts. I have that stuff and liners in them though.

PS We're talking 26" x 1.75-2.125" here, not Fat Franks.

PPS Sure is a funny place to put struts though. That model should have a spring on the front fender and a light in that bare spot IIRC.