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FYI Rolling Resistance

1867 Views 12 Replies 8 Participants Last post by tlg, 12 mo ago

get bikin

Discussion Starter · 12 mo ago

I need to delve into this site more but are some of the results showing higher PSI=lower rolling resistance

Bicycle Rolling Resistance | Rolling Resistance Tests

Bicycle Rolling Resistance publishes detailed reviews and articles about mountain bike and road bike tires, which have been tested on our rolling resistance roller

www.bicyclerollingresistance.com

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tlg

· #2 · 12 mo ago

This has been discussed here before. Don't delve into it too much. Unless you are riding your bicycle on a diamond plate drum. Then maybe it's useful to you.

Technical FAQ: Tire size and rolling resistance

How to size tires to rims and more discussion about tire hysteresis and aerodynamic drag.

www.velonews.com

As for the study you cite, the fact that Bicycle Rolling Resistance’s test setup has no damping means that its results must be taken with a huge grain of salt. They are simply inaccurate at higher pressures on rough surfaces. I explain here why damping in the test fixture matters. Bicycle Rolling Resistance’s tests always show an ever-decreasing rolling resistance with increased tire pressure, because there is a static load on its test wheel.

In real life, however, once the tire is hard enough that it bounces along, the damping of the rider causes the rolling resistance to increase steeply due to impedance. Our Paris-Roubaix rolling resistance tests at Wheel Energy Oy in Finland showed this, and you’ll see more of that in my upcoming test of gravel-tire rolling resistance. Without damping, the tire can skip across the diamond plate on Bicycle Rolling Resistance’s test drum, thus not revealing the losses due to impedance.

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Coolhand

· #3 · 12 mo ago

As noted, that takeaway is not correct- or we all would be riding around with 150psi in our tires. We are not. In fact, wider tires and lower psi is the trend post widespread RR testing.

The actual value in the BRR testing is not the absolutes (hence nobody riding at 200 psi), but rather in the direct comparisons of tires under the same conditions so you can see how various tires compare against each other. Now there are questions of direct translations to real world racing, and also certain fragile tires seem to do well on a steel drum but you can't finish first if you flat so again certain fast tires are fools gold.

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Lombard

· #4 · 12 mo ago

Coolhand said:
The actual value in the BRR testing is not the absolutes (hence nobody riding at 200 psi), but rather in the direct comparisons of tires under the same conditions so you can see how various tires compare against each other. Now there are questions of direct translations to real world racing, and also certain fragile tires seem to do well on a steel drum but you can't finish first if you flat so again certain fast tires are fools gold.

^^^Exactly this.^^^ Tires are always a compromise among different qualities such as rolling resistance, puncture resistance, ride quality, traction, longevity, etc.

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velodog

· #5 · 12 mo ago

CzeckMark said:
We used to ride around at 150 psi.
When tubulars were more common.
My 19s say max 125, my 23s say max 120, and my 25s say max 100 psi.
You cannot practically get higher pressures in wider tires, and wider are preferred for other reasons.

But to go faster on regular streets, go higher pressure - up to max of what tire says. -It is just harder to find 19s anymore.

You read the wrong book.

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tlg

· #6 · 12 mo ago

CzeckMark said:
But to go faster on regular streets, go higher pressure - up to max of what tire says.

Nope. This is unequivocally false.

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Kerry Irons

· #7 · 12 mo ago

CzeckMark said:
But to go faster on regular streets, go higher pressure - up to max of what tire says. -It is just harder to find 19s anymore.

Simply false. Higher pressure means less hysteresis losses due to reduced casing flex, but it means higher suspension losses due to the tire bouncing over road surface imperfections. There is a sweet spot for every tire and tire width where the sum of the two is lowest. For a modern road tire in the 25-28 mm width range, that is 80-90 psi. For wider tires, it is lower. You're quoting perceived wisdom from 20 years ago. Note that all the racers are now on wider tires. Data has the strange effect of changing behavior and thinking, if you let it.

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cxwrench

· #8 · 12 mo ago

CzeckMark said:
We used to ride around at 150 psi.
When tubulars were more common.
My 19s say max 125, my 23s say max 120, and my 25s say max 100 psi.
You cannot practically get higher pressures in wider tires, and wider are preferred for other reasons.

But to go faster on regular streets, go higher pressure - up to max of what tire says. -It is just harder to find 19s anymore.

Wrong.

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velodog

· #9 · 12 mo ago

CzeckMark said:
"Every racer and mechanic has a specific (usually top-secret) tire pressure that he or she considers to be the best, but there are some general guidelines."

" 'In general, with all of those variables [like weather and riders’ personal preference], that tire pressure is 8 to 8.5 bar for the road stages, and then 9.5 to 10 bar for the time-trial stages. Around 115 psi in the front and 125 psi in the back for the road stages and 130-135 psi for time-trial stages. And we drop that by 10 or 15 for rainy days,' veteran mechanic for teams like Garmin-Sharp and EF Education First Geoff Brown told us."

"They run about 10 psi lower in the front for more control as well, and with tubular tires, they tend to run slightly lower pressures. Clinchers need to be kept around 110 to 120 psi in order to avoid pinch-flatting."

And, I have 18 inch biceps.

14 Fun Facts About the Tour de France That You Can Use to Impress Your Friends

How do riders pee on the bike? Why is there no women’s Tour? Why is the leader’s jersey yellow? We’ve got the answers.

www.bicycling.com

You need 18" biceps to hold on to those tire pressure myths.

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duriel

· #10 · 12 mo ago

I have checked my clinchers after a ride when I thought my tire # were too low. I had 35psi in the front, I pumped them back up to my normal 50#, unless I have a high speed descent planned, then I go with 55# in front, 65# in rear. ... but I'm not a 'racer', but swing on by sometime and we'll see.
I haven't had a pinch flat in years. Pinch flats are more due to where you ride, if I was riding in pot hole heaven, I'd probably go with the high speed pressures I listed all the time.

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Lombard

· #11 · 12 mo ago

CzeckMark said:
But to go faster on regular streets, go higher pressure - up to max of what tire says.

This could not be more wrong.

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Kerry Irons

· #12 · 12 mo ago

CzeckMark said:
"Every racer and mechanic has a specific (usually top-secret) tire pressure that he or she considers to be the best, but there are some general guidelines."

" 'In general, with all of those variables [like weather and riders’ personal preference], that tire pressure is 8 to 8.5 bar for the road stages, and then 9.5 to 10 bar for the time-trial stages. Around 115 psi in the front and 125 psi in the back for the road stages and 130-135 psi for time-trial stages. And we drop that by 10 or 15 for rainy days,' veteran mechanic for teams like Garmin-Sharp and EF Education First Geoff Brown told us."

"They run about 10 psi lower in the front for more control as well, and with tubular tires, they tend to run slightly lower pressures. Clinchers need to be kept around 110 to 120 psi in order to avoid pinch-flatting."

And, I have 18 inch biceps.

Here's a hint. Much, if not most of the stuff you read in Bicycling Magazine is wrong, outdated, or at least disputable. It's been that way for decades. Even when you write them a letter correcting their obvious errors, they don't change and they don't publish the letter.

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tlg

· #13 · 12 mo ago

Kerry Irons said:
Here's a hint. Much, if not most of the stuff you read in Bicycling Magazine is wrong, outdated, or at least disputable. It's been that way for decades. Even when you write them a letter correcting their obvious errors, they don't change and they don't publish the letter.

Yea. Their magazine really is shit.
Those pressures are supposedly from EF Education First Geoff Brown. The date of the article: 2022

Well here is the same Geoff Brown in 2018:
Last week at the Tour, Business Insider spoke with Geoff Brown, the head mechanic of the EF Education First-Drapac p/b Cannondale team. This is Brown's 21st Tour, so he's seen his share of trends. (He used to wrench for one Lance Armstrong.)

We asked Brown about the trend to embrace wider tires and lower tire pressure, something that once seemed counterintuitive in pro cycling but has become a standard of sorts among the very top teams.

"It depends on the road surface, but 10 years ago the standard was 23mm tires at 8 or 8.5 bar, or 115, 120 psi," Brown said. "And now it's 25mm for regular road racing and 7 to 7.5 bar for front and rear, so a little less than 100 to 110 max on the bikes." So what's the deal?
"There seems to be a lot more real science behind cycling now," Brown explained. "A lower tire pressure with more surface contact translates to lower rolling resistance, which is one of the main factors.

An incredibly simple but revolutionary change at the Tour de France is being embraced by the world's fastest cyclists

Daniel McMahon/Business InsiderTo go faster, Tour de France teams are opting for wider tires and lower pressure.DREUX, France - There's no shortage of tech

www.businessinsider.in

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