Fat tire riders look like "fat heads."

On 7/4/2020 10:21 PM, Jeff Liebermann wrote:


https://en.wikipedia.org/wiki/Rolling_resistance
Rolling_resistance = CRF * Normal_force
where CRF is the coefficient of rolling friction.

CRF is determined by the road and tire materials and construction. It
doesn't change with inflation pressure.

I think that's an oversimplification, at least if we want to be
practical about bicycle tires. I think bike tires are a special case.
And this has been discussed since the days of Jobst.

Resistance to a bike's forward motion on level ground is usually thought
of as having three components: Mechanical friction in bearings, chain,
etc., which is small; Aerodynamic drag, which dominates at higher speeds
but is minimal at casual biker's or most mountain biker's speeds; and
rolling resistance, which is usually thought of as the simple formula
above, CRF * Normal_force and is mostly due to hysteresis and internal
friction in the tire itself, plus some scrubbing action against the
road. (Heavy sidewalls and anything beyond minimal tread increase that
internal friction.)

But there's another dominant effect, which is the resistance generated
by hysteresis inside the rider's body. Jiggling the rider's body tissue
generates internal friction loss and heats that tissue. That energy must
come from somewhere. It's energy that's not available to move the bike
forward, and the more jiggling, the less the bike speed.

If you want to decrease CRF * Normal_force, you could of course provide
a very hard, smooth surface and a hard, smooth tire. Build a rail bike!
Steel wheels on a steel rail have a very low CRF because there is almost
no deflection at the contact point, so very little internal friction and
hysteresis. But we ride on asphalt, concrete or dirt; and those have bumps.

So how about we use very high pressures in our tires to minimize tire
flex and its hysteresis losses? Sure, that works - but only on
super-smooth surfaces. It's great for wooden velodrome tracks. But on
real roads, let alone dirt, it's a disaster. The limit of that approach
is to ride an old Hard Tired Safety bike, with non-pneumatic tires and
wheels. As Dr. Dunlop and other showed over 100 years ago, a bicyclist
if far faster on air.

Why? Because even if the Hard Tired Safety reduces the losses where the
bike wheel and tire contact the ground, it greatly increases the amount
of jiggling in the rider's body. It sends energy into his body instead
of into forward motion. Besides, it beats the heck out of him and tires
him that way.

So maybe we should say bike motions has _four_ types of resistance: tiny
mechanical friction, speed-dependent aero drag, rolling resistance due
to flex and scrubbing of the tire itself, and body losses caused by
jiggling.

The last two are related. You want to minimize the total of the two.
Ideally, that would be done by choosing the proper tire width,
construction and pressure for each road surface. The smoothest surfaces
get the narrowest and highest pressure tires, and the roughest get
widest and lowest pressure ones. So choose your tires and pressures
based on the surfaces you ride. Just avoid super-cheap ones with heavy
tread patterns and thick sidewalls.

The fashion seems to be changing. I think I have only one friend who
still uses 18mm tires with 120+ psi. I never saw any evidence his bike
rolled better than mine with 28mm tires.

--
- Frank Krygowski

On 7/5/2020 11:46 AM, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area. That increases the ground
pressure, which causes the rolling resistance to increase. That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/
Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice. A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.





And there are limits to both. Quick search brings:

http://www.money4invest.com/infoshar...s-tire-safety/

and:
https://www.researchgate.net/figure/...fig1_268806919


Note thermal image of underinflated tire in 1st link (which
is what I searched), heat being energy transfer.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Sunday, 5 July 2020 13:10:07 UTC-4, Frank Krygowski wrote:
On 7/4/2020 8:21 PM, Rich wrote:
On Saturday, 4 July 2020 17:28:28 UTC-4, Andre Jute wrote:
On Saturday, July 4, 2020 at 4:21:07 AM UTC+1, Rich wrote:
Unless the stupid bike is powered, why endure that ridiculous rolling resistance?

You may be inexperienced or a troll, but I've already settled that question, he http://thorncyclesforum.co.uk/index....16360#msg16360

Andre Jute
I don't follow the fashion, I create it

PS. BTW, you're ill-informed. Low pressure balloons have a lower rolling resistance, so there is no "ridiculous rolling resistance". Where'd you ever pick up that dumb street corner myth?

You are complete wrong on this, it's not possible for a tire with a larger contact patch to have lower rolling-resistance than a small, higher inflation tire. Where did you learn physics, grade-school?
I know a lot of people on mountain bikes who switched from 2.25" tires to 1.9" to lower rolling resistance.


Assertions and "I know a guy" anecdotes without data and links don't get
much respect around here.

What do you know about mechanical hysteresis?

--
- Frank Krygowski

Yet a lot of times you use anecdotes about people you know, to try and prove a point.

Cheers

On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area. That increases the ground
pressure, which causes the rolling resistance to increase. That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/
Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice. A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.

I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error.

It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand.

Andre Jute
A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life.

On Sunday, July 5, 2020 at 5:23:18 PM UTC+1, AMuzi wrote:
On 7/4/2020 4:28 PM, Andre Jute wrote:
On Saturday, July 4, 2020 at 4:21:07 AM UTC+1, Rich wrote:
Unless the stupid bike is powered, why endure that ridiculous rolling resistance?

You may be inexperienced or a troll, but I've already settled that question, he http://thorncyclesforum.co.uk/index....16360#msg16360

Andre Jute
I don't follow the fashion, I create it

PS. BTW, you're ill-informed. Low pressure balloons have a lower rolling resistance, so there is no "ridiculous rolling resistance". Where'd you ever pick up that dumb street corner myth?


Maybe, maybe not.
Rolling resistance is a J curve for tires,

Maybe true for bicycle tyres, but if true for bicycle tyres, that merely shows they fall on a particular section of the more general S curve that suspension engineers generally gnash their teeth about. A J-curve implies some linearity across a considerable stretch of input/output, and there isn't a huge amount of linearity in rubber and hardwearing fibres and air arranged as tyres with their tubes in service at speed.

with extremely
narrow and firm tires suffering loss from bounce and
excessively wide tires from casing flex. Casing material and
thickness, tread material thickness and pattern, inflation
pressure and road surface also move that curve's shape and
height. There's some optimum width for each rider with each
tire design on each road.

A racing car and a fast bike are by definition extreme designs which compromise factors non-essential to their stated purpose.

Andre Jute
Be frightened, be very frightened of what the tyres will do to the beautiful geometry of your suspension design.

On Sunday, July 5, 2020 at 5:58:22 PM UTC+1, Frank Krygowski wrote:
On 7/5/2020 12:23 PM, AMuzi wrote:
On 7/4/2020 4:28 PM, Andre Jute wrote:.
....
....

+1. It's not simple.

--
- Frank Krygowski

Hey, at last Franki-boy gets something right. First, he agrees with Mr Muzi, which is always wise, and with me, which is smart for a clown I've taken against because otherwise I'll make a fool of him ever hour on the hour, and then he gives us the safe platitude: "It's not simple."

Now he's resting on his laurels...

Andre Jute
Applause, gentlemen, for Franki-boy getting something right. The opportunity to be nice to him probably won't arise for another year.

Andre Jute wrote:
On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area. That increases the ground
pressure, which causes the rolling resistance to increase. That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/
Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice. A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.

I'm not surprised, Jeff. Comparing the standard and the lightweight
folding Big Apples, and the thinner T19A tubes with the standard T19
tubes for 60x622 tyres, I found the lightweight versions to be very much
more comfortable with no degradation in handling and roadholding at the
limit, and not more fragile either on my rough but tarmacced lanes.
Handling is what the tyre does that is expected in response to normal
inputs up to the margin of error, roadholding is recovery from something
extreme stupid the rider does (or the road or environment does to him)
beyond the margin of error.

It must have been a common experience, because elements of the folding
Big Apple, and especially its ultra-flexible sidewall, were then spread
throughout the Big Apple range by Schwalbe, so that the folding tyre is
no longer a separate line within the brand.

Andre Jute
A life spent on the response of wheeled vehicles is not wasted. Sometimes
I wish I continued as a hot rodder all my life.


I tend to notice handling more than slight differences in rolling
resistance. Granted I’m not a racer trying to milk milliseconds from my
times. But cornering in a tight downhill is something I care about. My
HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for
me. Comfortable and good handling. Just my two cents but I find the
discussion on rolling resistance without handling considered to be a bit
useless.

On 7/5/2020 5:41 PM, Duane wrote:
Andre Jute wrote:
On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area. That increases the ground
pressure, which causes the rolling resistance to increase. That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/
Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice. A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.

I'm not surprised, Jeff. Comparing the standard and the lightweight
folding Big Apples, and the thinner T19A tubes with the standard T19
tubes for 60x622 tyres, I found the lightweight versions to be very much
more comfortable with no degradation in handling and roadholding at the
limit, and not more fragile either on my rough but tarmacced lanes.
Handling is what the tyre does that is expected in response to normal
inputs up to the margin of error, roadholding is recovery from something
extreme stupid the rider does (or the road or environment does to him)
beyond the margin of error.

It must have been a common experience, because elements of the folding
Big Apple, and especially its ultra-flexible sidewall, were then spread
throughout the Big Apple range by Schwalbe, so that the folding tyre is
no longer a separate line within the brand.

Andre Jute
A life spent on the response of wheeled vehicles is not wasted. Sometimes
I wish I continued as a hot rodder all my life.


I tend to notice handling more than slight differences in rolling
resistance. Granted I’m not a racer trying to milk milliseconds from my
times. But cornering in a tight downhill is something I care about. My
HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for
me. Comfortable and good handling. Just my two cents but I find the
discussion on rolling resistance without handling considered to be a bit
useless.


+1


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Sunday, July 5, 2020 at 11:41:11 PM UTC+1, Duane wrote:
Andre Jute wrote:
On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area. That increases the ground
pressure, which causes the rolling resistance to increase. That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/
Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice. A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.

I'm not surprised, Jeff. Comparing the standard and the lightweight
folding Big Apples, and the thinner T19A tubes with the standard T19
tubes for 60x622 tyres, I found the lightweight versions to be very much
more comfortable with no degradation in handling and roadholding at the
limit, and not more fragile either on my rough but tarmacced lanes.
Handling is what the tyre does that is expected in response to normal
inputs up to the margin of error, roadholding is recovery from something
extreme stupid the rider does (or the road or environment does to him)
beyond the margin of error.

It must have been a common experience, because elements of the folding
Big Apple, and especially its ultra-flexible sidewall, were then spread
throughout the Big Apple range by Schwalbe, so that the folding tyre is
no longer a separate line within the brand.

Andre Jute
A life spent on the response of wheeled vehicles is not wasted. Sometimes
I wish I continued as a hot rodder all my life.


I tend to notice handling more than slight differences in rolling
resistance. Granted I’m not a racer trying to milk milliseconds from my
times. But cornering in a tight downhill is something I care about. My
HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for
me. Comfortable and good handling. Just my two cents but I find the
discussion on rolling resistance without handling considered to be a bit
useless.

Yes, that is why my original article at http://thorncyclesforum.co.uk/index....16360#msg16360
considered roadholding (the mannered response of a tyre) and handling (its tolerance for rude inputs) at some length, and then considered comfort ahead of rolling resistance. By comparison, making a mountain out of rolling resistance, as Rich (and of course Franki-boy) try to do, because that is what they feel can understand from the welter of interrelated considerations, is a juvenile descent to triviality.

All the same, I clearly put a higher value on comfort than you do, Duane. Anyone for whom 23mm tyres at 90psi are the sweet spot must have an backside of cast iron.

Andre Jute
Tyres are horses for courses

On 7/5/2020 8:06 PM, AMuzi wrote:
On 7/5/2020 5:41 PM, Duane wrote:
Andre Jute wrote:
On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote:
On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann
wrote:

When you take the same rider and bike, and switch from slicks to
knobbies, you reduce the ground patch area.* That increases the ground
pressure, which causes the rolling resistance to increase.* That's one
reason why riding knobbies on pavement is like dragging an anchor.

I forgot to mumble something about tire pressu

"Everything You Think You Know About Bicycle Tire Pressure is Probably
Wrong"
https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/

Quoting:
Tire pressure has almost no effect on a tire’s speed.

If lower pressures don’t make tires slower, then you
can create wide tires with supple casings. You run
them at lower pressures, and you don’t give up any
performance on smooth roads. On rough roads, you
actually gain speed, because the tire (and you) bounce
less. And on all roads, you are more comfortable.

Conclusion
Tire pressure does not significantly affect your
bike’s rolling resistance, but the casing construction
of your tires does. This means that you can ride lower
pressures without going slower, and that wide tires
are no slower than narrow ones - as long as they have
similar casings. The fastest tires have supple casings
that consume less energy when they flex, and transmit
fewer vibrations, creating a win-win situation. These
tires roll super-fast no matter at what pressure you
run them.

So, you have a choice.* A hard stiff narrow tire at high pressure or
a soft flexible wide tire at low pressure.

I'm not surprised, Jeff. Comparing the standard and the lightweight
folding Big Apples, and the thinner T19A tubes with the standard T19
tubes for 60x622 tyres, I found the lightweight versions to be very much
more comfortable with no degradation in handling and roadholding at the
limit, and not more fragile either on my rough but tarmacced lanes.
Handling is what the tyre does that is expected in response to normal
inputs up to the margin of error, roadholding is recovery from something
extreme stupid the rider does (or the road or environment does to him)
beyond the margin of error.

It must have been a common experience, because elements of the folding
Big Apple, and especially its ultra-flexible sidewall, were then spread
throughout the Big Apple range by Schwalbe, so that the folding tyre is
no longer a separate line within the brand.

Andre Jute
A life spent on the response of wheeled vehicles is not wasted.
Sometimes
I wish I continued as a hot rodder all my life.


I tend to notice handling more than slight differences in rolling
resistance.* Granted I’m not a racer trying to milk milliseconds
from my
times.* But cornering in a tight downhill is something I care about.* My
HED wheels running 23mm conti folding tire at 90 psi are the sweet
spot for
me.* Comfortable and good handling.** Just my two cents but I find the
discussion on rolling resistance without handling considered to be a bit
useless.


+1

Except rolling resistance is quantifiable, at least to a degree.
Handling is a pretty nebulous item.

Similarly, I've been skeptical of Jan Heine's testimonies about bikes
that "plane" i.e. that have the precise degree of flexibility (not too
stiff) that allows the frame to somehow match his pedal strokes and go
faster with less effort. like a speedboat that planes over the water.

I'm not saying such a thing is impossible; but I'd like some hard
evidence "planing" exists other than his rave review. If some bikes
"plane" more than others, how can we measure it?

Likewise, if one tire "handles" better than others, how can we measure
it? Does anyone know if there is an actual metric?


--
- Frank Krygowski