Tire testing

On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski wrote:
http://velonews.competitor.com/where...ing-tires-fast

Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least over a
reasonable range. I think those ideas are still not widely accepted.

The article alludes to the suspension effect, i.e. that one important
function of the tire is to reduce energy losses due to upward
acceleration of the bike+rider. But I don't see that their steel drum
test (even with a diamond tread) really replicates that effect.

Jobst would say that they are correct in measuring only energy loss
within the tire. But ISTM that if the question is "what makes a tire
fast?" (the article's lead sentence) it needs to account for the fact
that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded bike (or
a steel drum). But it may be different if the tire is supporting an
actual human being on an actual road.


--
- Frank Krygowski

We had an argument in our riding group with everyone on one side and me on the other about these tests.

This is basically because the tests are not run under real-world conditions..

While you would normally run a wider tire so that you could reduce your tire pressure slightly to give a more comfortable ride this test gives all tires the same pressure.

But let us assume that this is the way people would in fact use these tires..

The wider tires under real-world conditions would still give higher friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let us assume that more or less normal 40/60 front/rear weight distribution. (This is why Specialized makes tire sets with the front and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would require a support of some 90 lbs or .77 square inches of contact area while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a smooth surface. Something that sure isn't available on most of the world's roads.. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire the less for and aft compression the tire requires to achieve it's contact patch. This is also the reason that tire compound makes such a difference. The softer the compound the more "smush" it will have to achieve the required contact patch with the least deflection of the tire cord. Or in another way of looking at it, you are effecting the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a larger air volume "crush" more - that is - in order to counter the loads on the tires by increasing their air pressure they have to compress and change shape much more than the narrower smaller volume tires. So if your one purpose is a lower rolling resistance the narrower tires will actually work better in the real world riding that we do.

But, you say, every year the grand tour riders switch back and forth between narrower and wider tires without ever seeming to decide what to do.

And this is because each year the courses of the grand tours change and what becomes more important is whether you want lower rolling resistance or better rough road comfort and braking. And these are not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more comfortable longer wheelbase bikes and lower rolling resistance 23 mm tires for descending faster.

On Wednesday, November 18, 2015 at 3:11:48 PM UTC-8, wrote:
On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski wrote:
http://velonews.competitor.com/where...ing-tires-fast

Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least over a
reasonable range. I think those ideas are still not widely accepted.

The article alludes to the suspension effect, i.e. that one important
function of the tire is to reduce energy losses due to upward
acceleration of the bike+rider. But I don't see that their steel drum
test (even with a diamond tread) really replicates that effect.

Jobst would say that they are correct in measuring only energy loss
within the tire. But ISTM that if the question is "what makes a tire
fast?" (the article's lead sentence) it needs to account for the fact
that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded bike (or
a steel drum). But it may be different if the tire is supporting an
actual human being on an actual road.


--
- Frank Krygowski

We had an argument in our riding group with everyone on one side and me on the other about these tests.

This is basically because the tests are not run under real-world conditions.

While you would normally run a wider tire so that you could reduce your tire pressure slightly to give a more comfortable ride this test gives all tires the same pressure.

But let us assume that this is the way people would in fact use these tires.

The wider tires under real-world conditions would still give higher friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let us assume that more or less normal 40/60 front/rear weight distribution. (This is why Specialized makes tire sets with the front and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would require a support of some 90 lbs or .77 square inches of contact area while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a smooth surface. Something that sure isn't available on most of the world's roads. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire the less for and aft compression the tire requires to achieve it's contact patch. This is also the reason that tire compound makes such a difference. The softer the compound the more "smush" it will have to achieve the required contact patch with the least deflection of the tire cord. Or in another way of looking at it, you are effecting the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a larger air volume "crush" more - that is - in order to counter the loads on the tires by increasing their air pressure they have to compress and change shape much more than the narrower smaller volume tires. So if your one purpose is a lower rolling resistance the narrower tires will actually work better in the real world riding that we do.

But, you say, every year the grand tour riders switch back and forth between narrower and wider tires without ever seeming to decide what to do.

And this is because each year the courses of the grand tours change and what becomes more important is whether you want lower rolling resistance or better rough road comfort and braking. And these are not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more comfortable longer wheelbase bikes and lower rolling resistance 23 mm tires for descending faster.

23 mm as opposed to what?

On Wednesday, November 18, 2015 at 3:22:00 PM UTC-8, Doug Landau wrote:
On Wednesday, November 18, 2015 at 3:11:48 PM UTC-8, wrote:
On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski wrote:
http://velonews.competitor.com/where...ing-tires-fast

Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least over a
reasonable range. I think those ideas are still not widely accepted.

The article alludes to the suspension effect, i.e. that one important
function of the tire is to reduce energy losses due to upward
acceleration of the bike+rider. But I don't see that their steel drum
test (even with a diamond tread) really replicates that effect.

Jobst would say that they are correct in measuring only energy loss
within the tire. But ISTM that if the question is "what makes a tire
fast?" (the article's lead sentence) it needs to account for the fact
that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded bike (or
a steel drum). But it may be different if the tire is supporting an
actual human being on an actual road.


--
- Frank Krygowski

We had an argument in our riding group with everyone on one side and me on the other about these tests.

This is basically because the tests are not run under real-world conditions.

While you would normally run a wider tire so that you could reduce your tire pressure slightly to give a more comfortable ride this test gives all tires the same pressure.

But let us assume that this is the way people would in fact use these tires.

The wider tires under real-world conditions would still give higher friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let us assume that more or less normal 40/60 front/rear weight distribution. (This is why Specialized makes tire sets with the front and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would require a support of some 90 lbs or .77 square inches of contact area while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a smooth surface. Something that sure isn't available on most of the world's roads. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire the less for and aft compression the tire requires to achieve it's contact patch. This is also the reason that tire compound makes such a difference. The softer the compound the more "smush" it will have to achieve the required contact patch with the least deflection of the tire cord. Or in another way of looking at it, you are effecting the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a larger air volume "crush" more - that is - in order to counter the loads on the tires by increasing their air pressure they have to compress and change shape much more than the narrower smaller volume tires. So if your one purpose is a lower rolling resistance the narrower tires will actually work better in the real world riding that we do.

But, you say, every year the grand tour riders switch back and forth between narrower and wider tires without ever seeming to decide what to do.

And this is because each year the courses of the grand tours change and what becomes more important is whether you want lower rolling resistance or better rough road comfort and braking. And these are not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more comfortable longer wheelbase bikes and lower rolling resistance 23 mm tires for descending faster.

23 mm as opposed to what?

25 mm or 28 mm. As the test said they thought that a 26 cotton Specialized would test better than their 24 and theoretically a 28 would test even better.

On 19/11/15 09:11, wrote:
On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski
wrote:
http://velonews.competitor.com/where...ing-tires-fast



Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least
over a reasonable range. I think those ideas are still not widely
accepted.

The article alludes to the suspension effect, i.e. that one
important function of the tire is to reduce energy losses due to
upward acceleration of the bike+rider. But I don't see that their
steel drum test (even with a diamond tread) really replicates that
effect.

Jobst would say that they are correct in measuring only energy
loss within the tire. But ISTM that if the question is "what makes
a tire fast?" (the article's lead sentence) it needs to account for
the fact that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded
bike (or a steel drum). But it may be different if the tire is
supporting an actual human being on an actual road.


-- - Frank Krygowski

We had an argument in our riding group with everyone on one side and
me on the other about these tests.

This is basically because the tests are not run under real-world
conditions.

While you would normally run a wider tire so that you could reduce
your tire pressure slightly to give a more comfortable ride this test
gives all tires the same pressure.

But let us assume that this is the way people would in fact use these
tires.

The wider tires under real-world conditions would still give higher
friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let
us assume that more or less normal 40/60 front/rear weight
distribution. (This is why Specialized makes tire sets with the front
and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would
require a support of some 90 lbs or .77 square inches of contact area
while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a
smooth surface. Something that sure isn't available on most of the
world's roads. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire
the less for and aft compression the tire requires to achieve it's
contact patch. This is also the reason that tire compound makes such
a difference. The softer the compound the more "smush" it will have
to achieve the required contact patch with the least deflection of
the tire cord. Or in another way of looking at it, you are effecting
the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a
continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a
larger air volume "crush" more - that is - in order to counter the
loads on the tires by increasing their air pressure they have to
compress and change shape much more than the narrower smaller volume
tires. So if your one purpose is a lower rolling resistance the
narrower tires will actually work better in the real world riding
that we do.

But, you say, every year the grand tour riders switch back and forth
between narrower and wider tires without ever seeming to decide what
to do.

And this is because each year the courses of the grand tours change
and what becomes more important is whether you want lower rolling
resistance or better rough road comfort and braking. And these are
not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more
comfortable longer wheelbase bikes and lower rolling resistance 23 mm
tires for descending faster.


I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.

--
JS

On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:
On 19/11/15 09:11, wrote:
On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski
wrote:
http://velonews.competitor.com/where...ing-tires-fast



Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least
over a reasonable range. I think those ideas are still not widely
accepted.

The article alludes to the suspension effect, i.e. that one
important function of the tire is to reduce energy losses due to
upward acceleration of the bike+rider. But I don't see that their
steel drum test (even with a diamond tread) really replicates that
effect.

Jobst would say that they are correct in measuring only energy
loss within the tire. But ISTM that if the question is "what makes
a tire fast?" (the article's lead sentence) it needs to account for
the fact that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded
bike (or a steel drum). But it may be different if the tire is
supporting an actual human being on an actual road.


-- - Frank Krygowski

We had an argument in our riding group with everyone on one side and
me on the other about these tests.

This is basically because the tests are not run under real-world
conditions.

While you would normally run a wider tire so that you could reduce
your tire pressure slightly to give a more comfortable ride this test
gives all tires the same pressure.

But let us assume that this is the way people would in fact use these
tires.

The wider tires under real-world conditions would still give higher
friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let
us assume that more or less normal 40/60 front/rear weight
distribution. (This is why Specialized makes tire sets with the front
and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would
require a support of some 90 lbs or .77 square inches of contact area
while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a
smooth surface. Something that sure isn't available on most of the
world's roads. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire
the less for and aft compression the tire requires to achieve it's
contact patch. This is also the reason that tire compound makes such
a difference. The softer the compound the more "smush" it will have
to achieve the required contact patch with the least deflection of
the tire cord. Or in another way of looking at it, you are effecting
the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a
continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a
larger air volume "crush" more - that is - in order to counter the
loads on the tires by increasing their air pressure they have to
compress and change shape much more than the narrower smaller volume
tires. So if your one purpose is a lower rolling resistance the
narrower tires will actually work better in the real world riding
that we do.

But, you say, every year the grand tour riders switch back and forth
between narrower and wider tires without ever seeming to decide what
to do.

And this is because each year the courses of the grand tours change
and what becomes more important is whether you want lower rolling
resistance or better rough road comfort and braking. And these are
not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more
comfortable longer wheelbase bikes and lower rolling resistance 23 mm
tires for descending faster.


I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.

--
JS

cuz the rear doesn't take as much wind resistance behind the seat tube. swap them.

On 19/11/15 12:15, Doug Landau wrote:
On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:

I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.



cuz the rear doesn't take as much wind resistance behind the seat tube. swap them.


While you might be correct about wind resistance, swapping the front and
back tyres would make no sense at all. The back tyre carries more load
and my arse and back need more cushioning. My hands and arms are happy
with the 23 on the front.

--
JS

On Thursday, November 19, 2015 at 11:35:55 AM UTC-8, James wrote:
On 19/11/15 12:15, Doug Landau wrote:
On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:

I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.



cuz the rear doesn't take as much wind resistance behind the seat tube. swap them.


While you might be correct about wind resistance, swapping the front and
back tyres would make no sense at all. The back tyre carries more load
and my arse and back need more cushioning. My hands and arms are happy
with the 23 on the front.

--
JS

What I am saying, and I am just regurgitating what I think I've learned here, not speaking from experience, is that there is a point of diminishing return on the rolling resistance curve, beyond which skinnier tires do have more RR than wider ones, and the reason for their use is their lower wind resistance. 20mm tires fall into this category. Whether said point occurs between 25s and 20s or between 28s and 25s or on the far side of 28s is the topic of much discussion.

At the same time, whether that point is at 25 or at 28 is academic, because all agree that a)the difference in RR is negligible..as you say 28s (and even 30s) at 90psi feel about as fast as 25s, and b)any difference is far overshadowed by the difference in effort required to spin them up.

On 11/19/2015 3:28 PM, Doug Landau wrote:
On Thursday, November 19, 2015 at 11:35:55 AM UTC-8, James wrote:
On 19/11/15 12:15, Doug Landau wrote:
On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:

I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.



cuz the rear doesn't take as much wind resistance behind the seat tube. swap them.


While you might be correct about wind resistance, swapping the front and
back tyres would make no sense at all. The back tyre carries more load
and my arse and back need more cushioning. My hands and arms are happy
with the 23 on the front.

--
JS

What I am saying, and I am just regurgitating what I think I've learned here, not speaking from experience, is that there is a point of diminishing return on the rolling resistance curve, beyond which skinnier tires do have more RR than wider ones, and the reason for their use is their lower wind resistance. 20mm tires fall into this category. Whether said point occurs between 25s and 20s or between 28s and 25s or on the far side of 28s is the topic of much discussion.

I'm sure that where that point occurs depends heavily on the road
surface roughness. And I don't mean only macro roughness, like pothole
patches. The difference in roughness between a well-paved asphalt road
and a "chip-seal" road is pretty extreme, as seen by a bike tire.

--
- Frank Krygowski

On 20/11/15 12:16, Phil W Lee wrote:
Frank Krygowski considered Thu, 19 Nov 2015
16:16:52 -0500 the perfect time to write:

On 11/19/2015 3:28 PM, Doug Landau wrote:
On Thursday, November 19, 2015 at 11:35:55 AM UTC-8, James wrote:
On 19/11/15 12:15, Doug Landau wrote:
On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:

I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.



cuz the rear doesn't take as much wind resistance behind the seat tube. swap them.


While you might be correct about wind resistance, swapping the front and
back tyres would make no sense at all. The back tyre carries more load
and my arse and back need more cushioning. My hands and arms are happy
with the 23 on the front.

--
JS

What I am saying, and I am just regurgitating what I think I've learned here, not speaking from experience, is that there is a point of diminishing return on the rolling resistance curve, beyond which skinnier tires do have more RR than wider ones, and the reason for their use is their lower wind resistance. 20mm tires fall into this category. Whether said point occurs between 25s and 20s or between 28s and 25s or on the far side of 28s is the topic of much discussion.

I'm sure that where that point occurs depends heavily on the road
surface roughness. And I don't mean only macro roughness, like pothole
patches. The difference in roughness between a well-paved asphalt road
and a "chip-seal" road is pretty extreme, as seen by a bike tire.

Indeed.
It takes quite a lot of power to keep a 200lb bag of jelly vibrating
in the way that is experienced by any rider on 23mm tyres on coarse
chip-seal roads.
Fit 28 or 32 mm tyres, and drop the pressures accordingly, and much
less power will be lost in that way.
The problem is that you can't generally change tyres for every change
in the road surface, so you just have to figure out what works on the
roads you ride.
It's quite possible that a slightly narrower tyre on the front may
make sense, as it does typically carry less weight.


That was my conclusion also. My hands and arms make pretty good shock
absorbers without wasting lots of energy jiggling all about - compared
to the rest of me that could be jiggled about more by a narrow and hard
back tyre.

--
JS

On Wednesday, November 18, 2015 at 5:58:17 PM UTC-8, James wrote:
On 19/11/15 09:11, wrote:
On Saturday, November 14, 2015 at 9:01:15 AM UTC-8, Frank Krygowski
wrote:
http://velonews.competitor.com/where...ing-tires-fast



Interesting - for example, the "wider=faster" claim, and the data
showing that tire pressure really doesn't matter much, at least
over a reasonable range. I think those ideas are still not widely
accepted.

The article alludes to the suspension effect, i.e. that one
important function of the tire is to reduce energy losses due to
upward acceleration of the bike+rider. But I don't see that their
steel drum test (even with a diamond tread) really replicates that
effect.

Jobst would say that they are correct in measuring only energy
loss within the tire. But ISTM that if the question is "what makes
a tire fast?" (the article's lead sentence) it needs to account for
the fact that energy is lost within the body of the rider.

IOW, this test may show what makes a tire "fast" on an unloaded
bike (or a steel drum). But it may be different if the tire is
supporting an actual human being on an actual road.


-- - Frank Krygowski

We had an argument in our riding group with everyone on one side and
me on the other about these tests.

This is basically because the tests are not run under real-world
conditions.

While you would normally run a wider tire so that you could reduce
your tire pressure slightly to give a more comfortable ride this test
gives all tires the same pressure.

But let us assume that this is the way people would in fact use these
tires.

The wider tires under real-world conditions would still give higher
friction than the narrower tires.

Why is this? Let us assume a 200 lb rider and a 25 lb bike. Also let
us assume that more or less normal 40/60 front/rear weight
distribution. (This is why Specialized makes tire sets with the front
and rear tires different from one another.)

At a slow speed (balance speed on smooth road) the front tire would
require a support of some 90 lbs or .77 square inches of contact area
while the rear 135 lbs and 1.16 square inch contact patch.

Now the testing machine assumes a smooth ride or an acceleration on a
smooth surface. Something that sure isn't available on most of the
world's roads. But nevertheless let's carry on.

A tire has a finite diameter. And this means that the wider the tire
the less for and aft compression the tire requires to achieve it's
contact patch. This is also the reason that tire compound makes such
a difference. The softer the compound the more "smush" it will have
to achieve the required contact patch with the least deflection of
the tire cord. Or in another way of looking at it, you are effecting
the roundness of the tire less.

But in the real world you aren't on a smooth surface. You are on a
continuously undulating and even a potholed surface.

In these conditions what you have is the wider tires that contain a
larger air volume "crush" more - that is - in order to counter the
loads on the tires by increasing their air pressure they have to
compress and change shape much more than the narrower smaller volume
tires. So if your one purpose is a lower rolling resistance the
narrower tires will actually work better in the real world riding
that we do.

But, you say, every year the grand tour riders switch back and forth
between narrower and wider tires without ever seeming to decide what
to do.

And this is because each year the courses of the grand tours change
and what becomes more important is whether you want lower rolling
resistance or better rough road comfort and braking. And these are
not a matter of road surface but rider preference.

For ordinary everyday riders like us on the group, we use more
comfortable longer wheelbase bikes and lower rolling resistance 23 mm
tires for descending faster.


I am more comfortable and seemingly just as fast using a 27mm rear tyre
(advertised as 25mm) inflated to between 80-90psi, compared to when I
used a 23mm tyre inflated to about 105psi. A 23mm front tyre is fine at
up to 100psi for me, but I usually let it run a bit softer.

And I find it more comfortable to ride alone rather than with a group that is keeping the pace do high for no reason than to complete a ride 10 minutes earlier.

On a couple of occasions I've let the greyhounds get far ahead and then run them down on their favorite hard climbs so that they realize that I can ride faster than them and don't because I don't like to ride fast all the time everywhere. But it never seems to sink in. And so every ride there they are again jack-rabbiting off. So I'm spending more and more time just going on lone rides.