35-406 (20 x 1.35) Tires. Ouch!

[sms]

The Schwalbe Marathon tires (20 x 1.35) which were standard equipment on
my Dahon are deteriorating. Apparently sidewall deterioration is a
problem with the old Marathon tires. But these are pretty old so it's
not unexpected.

Went looking for some replacement tires. This is not a bike shop item of
course. Was looking for the same size I have now, 35-406 (20 x 1.35). I
could go up to 40-406 but I don't really want to and the 40-406 have a
much lower maximum PSI.

20" tires may be smaller, with less material, but they are quite
expensive since the volumes are not there and the selection is pretty
sparse in the narrower widths.

$45 each for the Schwalbe Marathon Plus which has more puncture
resistance than the standard Marathon.
<http://www.schwalbetires.com/bike_tires/road_tires/Marathon_Plus_HS440>.

[Andre Jute]

Though it is true that the Marathon Plus is almost perfectly punctureproof, it also offers the nastiest, harshest ride imaginable and is incredibly difficult to get on the rim even at 700 size. Definitely not reclmmended except if you are desperate for pu ctureproofing and longevity.

Andre Jute
Been there, done that, don't wear t-shirts

[avag...@gmail.com]

http://goo.gl/TtT2gS

[avag...@gmail.com]

On Sunday, March 6, 2016 at 8:25:52 AM UTC-5, avag...@gmail.com wrote:
> http://goo.gl/TtT2gS

Cook the Godless Atheist and GooGoons disabled our shortlink ! Zapman

[Tosspot]

On 06/03/16 12:18, Andre Jute wrote:
> Though it is true that the Marathon Plus is almost perfectly
> punctureproof, it also offers the nastiest, harshest ride imaginable

My Marathon Supremes were a nice ride, and I enjoyed fixing the
punctures every 500km :-(

> and is incredibly difficult to get on the rim even at 700 size.
> Definitely not reclmmended except if you are desperate for pu
> ctureproofing and longevity.

This is simply poor fitting technique. The magic blue gunk tends to
spread the tyre laterally meaning you have to be *very* careful to get
the bead into the well. Old toe straps or zip ties can really help
here. Other than that, I've fitted 20x1.35s (trike plus cargo bike),
26" and 700C all without using tools.

The latest Marathon Plus Tour seem to be hold up very well. Just
approaching 2,500 kms on mine and no appreciable wear. I'll likely swap
from for back in the summer and see how they are at the 5,000 point.

[avag...@gmail.com]

what's 'magic blue gunk' ?

I dunno. Used Panaracer messengers for uh around town loaded. Wooden, Unleanable. Like an arrow ? Touring ? unacceptable ..in the
YOU GOTTA BE KIDDING category

https://www.google.com/#q=blog+bicycle+tire+marathon+supremes

1500 miles ? 500 miles.

what's the problem with $45 ? too much skiing ?

[sms]

On 3/6/2016 7:11 AM, Tosspot wrote:

> This is simply poor fitting technique. The magic blue gunk tends to
> spread the tyre laterally meaning you have to be *very* careful to get
> the bead into the well. Old toe straps or zip ties can really help
> here. Other than that, I've fitted 20x1.35s (trike plus cargo bike),
> 26" and 700C all without using tools.
>
> The latest Marathon Plus Tour seem to be hold up very well. Just
> approaching 2,500 kms on mine and no appreciable wear. I'll likely swap
> from for back in the summer and see how they are at the 5,000 point.

I've had only one flat on the Dahon in the 15+ years I've owned it and I
do seem to recall that it was rather a pain to get the stock Marathon
(non-plus) off the rim.

We'll see. They no longer make the 20 x 1.35 in the Marathon non-plus.
There is only one Schwabe 35-406 tire rate for at least 100 psi and that
is the Marathon Plus.
<http://www.schwalbetires.com/product_search?field_etrto_value_many_to_one%5B%5D=406-35>.

The Dahon's ride is so rough already that I don't think that the
Marathon Plus is going to be a contributing factor in making it any rougher.

It's a real pain to get a flat on the rear wheel of the Dahon, so I want
flat protection.

[Tosspot]

On 06/03/16 19:26, sms wrote:
> On 3/6/2016 7:11 AM, Tosspot wrote:
>
>> This is simply poor fitting technique. The magic blue gunk tends
>> to spread the tyre laterally meaning you have to be *very* careful
>> to get the bead into the well. Old toe straps or zip ties can
>> really help here. Other than that, I've fitted 20x1.35s (trike
>> plus cargo bike), 26" and 700C all without using tools.
>>
>> The latest Marathon Plus Tour seem to be hold up very well. Just
>> approaching 2,500 kms on mine and no appreciable wear. I'll likely
>> swap from for back in the summer and see how they are at the 5,000
>> point.
>
> I've had only one flat on the Dahon in the 15+ years I've owned it
> and I do seem to recall that it was rather a pain to get the stock
> Marathon (non-plus) off the rim.
>
> We'll see. They no longer make the 20 x 1.35 in the Marathon
> non-plus. There is only one Schwabe 35-406 tire rate for at least 100
> psi and that is the Marathon Plus.
> <http://www.schwalbetires.com/product_search?field_etrto_value_many_to_one%5B%5D=406-35>.

It might have been the 35s I used, was 9 months ago. The trike ones
were thinner I'm sure, but that was at least 6 years back.

> The Dahon's ride is so rough already that I don't think that the
> Marathon Plus is going to be a contributing factor in making it any
> rougher.
>
> It's a real pain to get a flat on the rear wheel of the Dahon, so I
> want flat protection.

You are not wrong brother. I put a horizontal dropout commuter together
with a Nexus-11, mudguards and rack. I bought another frame after about
2 years. It was just *too* painful to undo the rack, mudguards, shifter
to get the back wheel off.

"How often did you need to get the back wheel off?" I hear you ask.
Once is too fucking often! Surly LHT Disc with a singulator sorted that
problem out :-)

Never ridden a Dahon.

[avag...@gmail.com]

IS COOK AN ATHEIST ?


https://www.biketiresdirect.com/search?kw2=20%20x%201.3


$12 SKI VERMONT

[avag...@gmail.com]

Never ridden a Dahon.

MAY THE WIND BE WITH YOU

[Andre Jute]

On Sunday, March 6, 2016 at 3:11:43 PM UTC, Tosspot wrote:
> On 06/03/16 12:18, Andre Jute wrote:
> > Though it is true that the Marathon Plus is almost perfectly
> > punctureproof, it also offers the nastiest, harshest ride imaginable
>
> My Marathon Supremes were a nice ride, and I enjoyed fixing the
> punctures every 500km :-(

You're the only one who thinks so, Tosser.

> > and is incredibly difficult to get on the rim even at 700 size.
> > Definitely not reclmmended except if you are desperate for pu
> > ctureproofing and longevity.
>
> This is simply poor fitting technique. The magic blue gunk tends to
> spread the tyre laterally meaning you have to be *very* careful to get
> the bead into the well. Old toe straps or zip ties can really help
> here. Other than that, I've fitted 20x1.35s (trike plus cargo bike),
> 26" and 700C all without using tools.

What are you, some kind of a troll? Or is this your attempt at humour?

> The latest Marathon Plus Tour seem to be hold up very well. Just
> approaching 2,500 kms on mine and no appreciable wear. I'll likely swap
> from for back in the summer and see how they are at the 5,000 point.

There are several more desirable tyres in the loose Schwalbe Marathon family; on anyone's scale the Plus, except for commuting through the gutters of the ghetto, is the least desirable. And that includes on mileage. My cushy Big Apple Liteskins, for instance, have long since passed the 8500km mark that is 70% further than you hope to get on your Plus. (My Plus made 3200km with wear left on them when my patience ran out, so you'll probably get the 5000km you're hoping for.)

Andre Jute
Just the fax, mam

[avag...@gmail.com]

here dah fax Dude

5200 miles



http://41.media.tumblr.com/dc512d10cf12b9c2b22731698e2dadb1/tumblr_mmal38W13E1qdm3e3o1_500.jpg


eyeyhahhahha

[sms]

On 3/6/2016 12:09 PM, Tosspot wrote:

<snip>

> "How often did you need to get the back wheel off?" I hear you ask.
> Once is too fucking often! Surly LHT Disc with a singulator sorted that
> problem out :-)

IIRC, I fixed the flat without removing the wheel.

[Tosspot]

On 06/03/16 23:24, Andre Jute wrote:
> On Sunday, March 6, 2016 at 3:11:43 PM UTC, Tosspot wrote:
>> On 06/03/16 12:18, Andre Jute wrote:
>>> Though it is true that the Marathon Plus is almost perfectly
>>> punctureproof, it also offers the nastiest, harshest ride imaginable
>>
>> My Marathon Supremes were a nice ride, and I enjoyed fixing the
>> punctures every 500km :-(
>
> You're the only one who thinks so, Tosser.

Unforunately a bloke at work agrees with me. They were just to puncture
prone. Nice ride though, but not for a commuter. I dunno where he
went, but I went back, not a puncture in sight.

[Tosspot]

It's still a pain with mudguards and rack. I don't like the chain
tensioner, but with discs you really want the rear wheel to stay in
exactly the same place, so vertical dropouts are a Good Thing[TM] but
then you *have* to have a tensioner. Have to say, tucks out the way and
does the job.

[somebody]

On Sun, 6 Mar 2016 03:18:10 -0800 (PST), Andre Jute
<fiul...@yahoo.com> wrote:

>Though it is true that the Marathon Plus is almost perfectly punctureproof, it also offers the nastiest, harshest ride imaginable and is incredibly difficult to get on the rim even at 700 size. Definitely not reclmmended except if you are desperate for pu ctureproofing and longevity.

Only hard to mount for the ignorant.

And it's a decent ride. Have been using them on daily commuter for
several years. Kinda miss fixing flats...

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[avag...@gmail.com]

A bike needs disemblee for a flat ?

SKIVERMONT.COM.

[avag...@gmail.com]

[sms]

On 3/6/2016 10:23 PM, Tosspot wrote:
> On 06/03/16 23:24, Andre Jute wrote:
>> On Sunday, March 6, 2016 at 3:11:43 PM UTC, Tosspot wrote:
>>> On 06/03/16 12:18, Andre Jute wrote:
>>>> Though it is true that the Marathon Plus is almost perfectly
>>>> punctureproof, it also offers the nastiest, harshest ride imaginable
>>>
>>> My Marathon Supremes were a nice ride, and I enjoyed fixing the
>>> punctures every 500km :-(
>>
>> You're the only one who thinks so, Tosser.
>
> Unforunately a bloke at work agrees with me. They were just to puncture
> prone. Nice ride though, but not for a commuter. I dunno where he
> went, but I went back, not a puncture in sight.

The Marathon Supreme and the Big Apple are more puncture prone because
they are pretty low pressure tires. And of course low pressure tires
will give you a more comfortable ride if you don't care about rolling
resistance. The Marathon Plus does sacrifice some rolling resistance for
puncture protection, but in the case of a Nexus 7 hub the extra rolling
resistance is offset by the time it takes to repair a puncture.

[Andre Jute]

On Monday, March 7, 2016 at 10:28:23 AM UTC, somebody wrote:
> On Sun, 6 Mar 2016 03:18:10 -0800 (PST), Andre Jute

> <> wrote:
>
> >Though it is true that the Marathon Plus is almost perfectly punctureproof, it also offers the nastiest, harshest ride imaginable and is incredibly difficult to get on the rim even at 700 size. Definitely not reclmmended except if you are desperate for pu ctureproofing and longevity.
>
> Only hard to mount for the ignorant.

Oh, I don't know. Are you really calling Sheldon and Chalo ignorant? Or is this contrary opinion, not shared by most perfectly sensible cyclists, just your expression of your dislike for me, anonymous "somebody"?

> And it's a decent ride. Have been using them on daily commuter for
> several years. Kinda miss fixing flats...

Horses for courses, tyres for arses. If you have a butt of granite, you might consider the Marathon Plus a "decent ride", compared to, say, an ultra-narrow, ultra-high pressure road tyre. Who knows how long ago some old roadie's coccyx was pounded through his brain?

Andre Jute
Sybarite cyclist

[avag...@gmail.com]

WHAT is a yachtsman looking for in a go to bike ?

BTW yachters are recovering clawstrophobics....on the cycle they're all smiles.

that they are in the market for the finer nuances of tire performance is kinda moot

[Andre Jute]

On Monday, March 7, 2016 at 2:38:13 PM UTC, sms wrote:

> The Marathon Supreme and the Big Apple are more puncture prone because
> they are pretty low pressure tires.

You should feel how hard a Big Apple is even down at 2 bar, Scharfie. I doubt normal balloon pressures of 2-3 bar are puncture prone, especially on near-slicks like the Big Apple where there is no tread for anything to stick in if it doesn't puncture the protection belt immediately.

In any event, my Big Apples went 8500km before getting a single puncture, and then it was a snakebite from crashing through a pothole at 51kph at the bottom of a hill with only 1.6 bar of inflation while I was testing the limits of the cushion.

> And of course low pressure tires
> will give you a more comfortable ride if you don't care about rolling
> resistance.

Scharfie, Scharfie! It's this sort of carelessness that invites idiots like Krygowski to class you with the artists like me. Great big fat, near-slick, low pressure tyres like the Big Apple have LESS rolling resistance than narror and especially treaded tyres. Krygowski will shortly be giving you the reference to the study by the Technical University of Cologn that proved this conclusively.

> The Marathon Plus does sacrifice some rolling resistance for
> puncture protection, but in the case of a Nexus 7 hub the extra rolling
> resistance is offset by the time it takes to repair a puncture.

I hate to sound like the contrary clowns further up the thread (hey, maybe Tosspot is sincere, only inexperienced -- now there's a thought!) but I actually measured a known circuit I rode daily then on on Vredesteins (standard Gazelle fitment back then), Contis (cheap shit touring tyres that my LBS swore by) and Marathon Plus, and the Plus was by a good margin the fastest tyre. It was just nasty to ride on unless you stayed exclusively on smooth tarmac, which where I live is impossible.

Andre Jute
Observation is the foundation of science

[sms]

What would be ideal is a wider tire that is rated for higher PSI, but
the PSI rating goes down as the width increases.

The reason that the wider tires have more rolling resistance is because
they are not able to be inflated to as high a pressure as the narrower
tires. If they were higher pressure there would actually be an advantage
to the greater width in terms of rolling resistance (as
counter-intuitive as that may seem).

For the Marathon Plus, the 35-406 (20 x 1.35) has a maximum PSI 43%
greater than the 30% wider 47-406 (20 x 1.75).

The price, with shipping was almost exactly the same.

Maybe I should have just gone with the 100 psi Kenda Kwest 40-406 (20 x
1.5) for $13 each.

[Tosspot]

On 07/03/16 18:00, Andre Jute wrote:
> On Monday, March 7, 2016 at 10:28:23 AM UTC, somebody wrote:
>> On Sun, 6 Mar 2016 03:18:10 -0800 (PST), Andre Jute <> wrote:
>>
>>> Though it is true that the Marathon Plus is almost perfectly
>>> punctureproof, it also offers the nastiest, harshest ride
>>> imaginable and is incredibly difficult to get on the rim even at
>>> 700 size. Definitely not reclmmended except if you are desperate
>>> for pu ctureproofing and longevity.
>>
>> Only hard to mount for the ignorant.
>
> Oh, I don't know. Are you really calling Sheldon and Chalo ignorant?
> Or is this contrary opinion, not shared by most perfectly sensible
> cyclists, just your expression of your dislike for me, anonymous
> "somebody"?

You'll have to cite on that one, my Google mojo deserted me.

[somebody]

On Mon, 7 Mar 2016 09:00:20 -0800 (PST), Andre Jute
<fiul...@yahoo.com> wrote:

>On Monday, March 7, 2016 at 10:28:23 AM UTC, somebody wrote:
>> On Sun, 6 Mar 2016 03:18:10 -0800 (PST), Andre Jute
>> <> wrote:
>>
>> >Though it is true that the Marathon Plus is almost perfectly punctureproof, it also offers the nastiest, harshest ride imaginable and is incredibly difficult to get on the rim even at 700 size. Definitely not reclmmended except if you are desperate for pu ctureproofing and longevity.
>>
>> Only hard to mount for the ignorant.
>
>Oh, I don't know. Are you really calling Sheldon and Chalo ignorant? Or is this contrary opinion, not shared by most perfectly sensible cyclists, just your expression of your dislike for me, anonymous "somebody"?

I have no problems changing my Marathon+ tires. Apparently YMMV.
Check the youtube video where someone changes one with no levers. Yes,
it can be done. Do a little learning and try again.

>
>> And it's a decent ride. Have been using them on daily commuter for
>> several years. Kinda miss fixing flats...
>
>Horses for courses, tyres for arses.

And science saves the day.

[sms]

On 3/7/2016 11:57 AM, sms wrote:

<snip>

> For the Marathon Plus, the 35-406 (20 x 1.35) has a maximum PSI 43%
> greater than the 30% wider 47-406 (20 x 1.75).
>
> The price, with shipping was almost exactly the same.

Oops, actually the 47-406 worked out to $37 each while the 35-406 were
$45 each.

I realized another good reason for the narrower tires, and it's the
limited fender clearance on the folding bike.

[avag...@gmail.com]

Observation is the foundation of science

https://s3.amazonaws.com/lowres.cartoonstock.com/miscellaneous-village-villager-village_idiot-darn-toe-gra050217_low.jpg

[Tosspot]

On 07/03/16 20:57, sms wrote:
> On 3/6/2016 10:25 PM, Tosspot wrote:
>> On 07/03/16 01:45, sms wrote:
>>> On 3/6/2016 12:09 PM, Tosspot wrote:
>>>
>>> <snip>
>>>
>>>> "How often did you need to get the back wheel off?" I hear you ask.
>>>> Once is too fucking often! Surly LHT Disc with a singulator sorted
>>>> that
>>>> problem out :-)
>>>
>>> IIRC, I fixed the flat without removing the wheel.
>>
>> It's still a pain with mudguards and rack. I don't like the chain
>> tensioner, but with discs you really want the rear wheel to stay in
>> exactly the same place, so vertical dropouts are a Good Thing[TM] but
>> then you *have* to have a tensioner. Have to say, tucks out the way and
>> does the job.
>
> What would be ideal is a wider tire that is rated for higher PSI, but
> the PSI rating goes down as the width increases.
>
> The reason that the wider tires have more rolling resistance is because
> they are not able to be inflated to as high a pressure as the narrower
> tires. If they were higher pressure there would actually be an advantage
> to the greater width in terms of rolling resistance (as
> counter-intuitive as that may seem).

Certainly fooled the guys at Schwalbe;

http://www.schwalbe.com/gb/rollwiderstand.html

"Wider tyres roll better than narrower tyres. This statement generally
invokes skepticism, nevertheless, with tyres at the same pressure a
narrower tyre deflects more and so deforms more"

And Sheldon

http://www.sheldonbrown.com/tires.html

"The short answer to this question is that, yes, a wider tire of similar
construction will have lower rolling resistance than a narrower one at
the same pressure. "

Although he goes on to qualify this this.

> For the Marathon Plus, the 35-406 (20 x 1.35) has a maximum PSI 43%
> greater than the 30% wider 47-406 (20 x 1.75).
>
> The price, with shipping was almost exactly the same.
>
> Maybe I should have just gone with the 100 psi Kenda Kwest 40-406 (20 x
> 1.5) for $13 each.

Surely, It's really down to how you feel about fixing punctures. A QR
deraileur system a rear wheel can be patched on the road in 5 minutes
with a "get you home" pump (Morph?). Where as if it requires undoing
rack, mudguard, gear cable, torque converter, then ytou *really* want
puncture resistance.

But the internet saves the day!

http://www.bicyclerollingresistance.com/

Who'd have thought... :-)

[avag...@gmail.com]

DUH.....TDF

Tires are made during one time span production periods with quantity produced figured with demand and concomitant elements of obsolescence.

Dahoners then buy hard tires.

Wannabe racers get soft tires

Like oatmeal ?

[sms]

On 3/7/2016 10:26 PM, Tosspot wrote:

<snip>

> "Wider tyres roll better than narrower tyres. This statement generally
> invokes skepticism, nevertheless, with tyres at the same pressure a
> narrower tyre deflects more and so deforms more"

As I explained, the tires are NOT the same pressure. The narrower tires
almost always have a higher maximum pressure. This lowers rolling
resistance, offsetting the advantage of a wider tire which operates at a
lower pressure.

There is no precise formula for how much increased tire pressure reduces
rolling resistance and how much increased width reduces rolling
resistance. The 43% higher pressure Marathon Plus 35-406 might be better
than the 30% wider 47-406 or it might not be. The puncture protection of
the Marathon Plus might make the increased puncture protection of a
higher pressure tire unnecessary.

[Frank Krygowski]

On 3/8/2016 1:26 AM, Tosspot wrote:
>
> But the internet saves the day!
>
> http://www.bicyclerollingresistance.com/
>

I'm a bit skeptical of their values, because of the nature of their
test. Yes, it's the typical RR test, running the wheel and tire on a
rotating drum. But I that measures only the losses within the tire
rubber, not the closely related phenomenon of suspension losses in the
mass of the bike+rider. Wider tires are better at reducing those latter
losses.

Jobst used to say those losses are not tire losses, or something
similar. But they are the precise reason we use pneumatics in the first
place. I think they need to be somehow modeled and included.


--
- Frank Krygowski

[Tosspot]

I always thought a lower pressure helped wrt to punctures as the tyre
can deform over the offending object. So wide soft tyres would be
better than narrow hard ones for the same pollyputthekettleon liners.
Ignoring snake bites.

Am I completely wrong on this?

[Duane]

I think the idea is that softer tires are more likely to pick up debris
that can be worked into the tube. And since you're ignoring snake
bites, you must already know about lower pressure.

[sms]

I don't know if any scientific, double-blind, study has been done, but
my understanding is that at higher pressures a sharp object has more
difficulty penetrating the tire and tube, though the tire construction
has more to do with it than the pressure. Of course pinch flats are much
more common at lower pressure.

[Roger Merriman]

I've not seen any science to back up low pressures or high pressures
helping puncture resistance.

infact very sure it's old wifes tales.

its all about construction.

Roger Merriman

[Roger Merriman]

somebody <som...@somewhere.com> wrote:

> On Mon, 7 Mar 2016 09:00:20 -0800 (PST), Andre Jute
> <fiul...@yahoo.com> wrote:
>
> >On Monday, March 7, 2016 at 10:28:23 AM UTC, somebody wrote:
> >> On Sun, 6 Mar 2016 03:18:10 -0800 (PST), Andre Jute
> >> <> wrote:
> >>
> >> >Though it is true that the Marathon Plus is almost perfectly
> >> punctureproof, it also offers the nastiest, harshest ride imaginable
> >> and is >>>incredibly difficult to get on the rim even at 700 size.
> >> Definitely >>>not reclmmended except if you are desperate for pu
> >> ctureproofing and >>>longevity.
> >>
> >> Only hard to mount for the ignorant.
> >
> >Oh, I don't know. Are you really calling Sheldon and Chalo ignorant? Or
>>is this contrary opinion, not shared by most perfectly sensible
>>cyclists, just your expression of your dislike for me, anonymous
>>"somebody"?
>
> I have no problems changing my Marathon+ tires. Apparently YMMV.
> Check the youtube video where someone changes one with no levers. Yes,
> it can be done. Do a little learning and try again.

its harder the thinner the tyre, I used to have 700*25 on one bike, and
that was a bit stiff.

once you got to 28s like my wife had on her bike for a few years and I
had 38s on a hybrid for a few years, both are easy to do, did it largly
one handed at the pub one day. I'm sure it helps I have strong hands etc
but even so M+ repucation to fit is way behond the reality.

>
> >
> >> And it's a decent ride. Have been using them on daily commuter for
> >> several years. Kinda miss fixing flats...
> >
> >Horses for courses, tyres for arses.
>
> And science saves the day.
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus

Roger Merriman

[Frank Krygowski]

I think variation in pressure has only a small effect over the usual
range of pressures that work with a given tire.

One possible effect might be this: At higher pressures, there's more
tensile stress on the tire. A shard of glass might be able to penetrate
somewhat easier because, to a degree, the tire material is being pulled
aside as the glass pushes its way in.

But again, I think there are other factors that are much more important.

--
- Frank Krygowski

[Andre Jute]

Very big indirect effects also from the stiffness or otherwise of the sidewalls. None of this is simple and straightforward, and some of it is couterintuitive.

I'm at the Iditarod races this week and next, so you guys are on your own. Most of you'll get it wrong anyway, regardless of whether I'm here or not.

Andre Jute

[sms]

On 3/8/2016 12:42 PM, Roger Merriman wrote:

<snip>

> I've not seen any science to back up low pressures or high pressures
> helping puncture resistance.
>
> infact very sure it's old wifes tales.
>
> its all about construction.

Construction is the major factor, but given the same construction a
higher pressure tire is less likely to be punctured than a lower
pressure tire.

From the Schwalbe web site: "The following applies for the road: The
higher the inflation pressure the lower the rolling resistance of the
tire. The susceptibility to punctures is also lower with high pressure."
<http://www.schwalbetires.com/tech_info/inflation_pressure>

I would trust Schwalbe on this. There's no reason for them to lie about
this.

When it comes to pinch flats, rather then punctures, it's not really
about tires with a higher PSI rating versus a lower PSI rating, it's
about the tires being under-inflated.

Frank Berto writes:
"Under-inflated tires get more impact punctures because, upon riding
into an unyielding object, the tire compresses so much that the inner
tube gets pinched between the edge of the rim and the rock, pothole,
railroad track or whatever you've hit. You can identify this puncture
because it produces two small holes several millimeters apart. This is
why it's also known as a "snake bite.""
<http://www.bccclub.org/documents/Tireinflation.pdf>

[Roger Merriman]

sms <scharf...@geemail.com> wrote:

> On 3/8/2016 12:42 PM, Roger Merriman wrote:
>
> <snip>
>
> > I've not seen any science to back up low pressures or high pressures
> > helping puncture resistance.
> >
> > infact very sure it's old wifes tales.
> >
> > its all about construction.
>
> Construction is the major factor, but given the same construction a
> higher pressure tire is less likely to be punctured than a lower
> pressure tire.
>
> From the Schwalbe web site: "The following applies for the road: The
> higher the inflation pressure the lower the rolling resistance of the
> tire. The susceptibility to punctures is also lower with high pressure."
> <http://www.schwalbetires.com/tech_info/inflation_pressure>
>
> I would trust Schwalbe on this. There's no reason for them to lie about
> this.
>

that looks like a old document TBH it doesn't refernce anything. maybe
they do have some facts to back this up, but with out them it is just
opinion.

it doesn't mention or split pinch vs pentration clearly together the
risk from pinch increases as the pressures drop.

> When it comes to pinch flats, rather then punctures, it's not really
> about tires with a higher PSI rating versus a lower PSI rating, it's
> about the tires being under-inflated.
>
> Frank Berto writes:
> "Under-inflated tires get more impact punctures because, upon riding
> into an unyielding object, the tire compresses so much that the inner
> tube gets pinched between the edge of the rim and the rock, pothole,
> railroad track or whatever you've hit. You can identify this puncture
> because it produces two small holes several millimeters apart. This is
> why it's also known as a "snake bite.""
> <http://www.bccclub.org/documents/Tireinflation.pdf>

Roger Merriman

[sms]

On 3/8/2016 3:18 PM, Roger Merriman wrote:
> sms <scharf...@geemail.com> wrote:
>
>> On 3/8/2016 12:42 PM, Roger Merriman wrote:
>>
>> <snip>
>>
>>> I've not seen any science to back up low pressures or high pressures
>>> helping puncture resistance.
>>>
>>> infact very sure it's old wifes tales.
>>>
>>> its all about construction.
>>
>> Construction is the major factor, but given the same construction a
>> higher pressure tire is less likely to be punctured than a lower
>> pressure tire.
>>
>> From the Schwalbe web site: "The following applies for the road: The
>> higher the inflation pressure the lower the rolling resistance of the
>> tire. The susceptibility to punctures is also lower with high pressure."
>> <http://www.schwalbetires.com/tech_info/inflation_pressure>
>>
>> I would trust Schwalbe on this. There's no reason for them to lie about
>> this.
>>
> that looks like a old document TBH it doesn't refernce anything. maybe
> they do have some facts to back this up, but with out them it is just
> opinion.

I don't think that one of the largest makers of tires has to reference
anything or do a specific study when they make a statement as obvious
and innocuous as that. It's not like you or I stating it. They _are_ the
reference.

And it's not an old document, it's currently on their site under the
"Tech Info" section at <http://www.schwalbetires.com/tech_info>.

It is true that tire construction is the major factor in puncture
resistance, but all things being equal, a higher pressure tire will get
fewer punctures.

[John B.]

Bike Quarterly published a tire loss study, authored by Jan Heine,
which states in part that "At higher pressures, internal losses due to
flexing of the casing decrease, but suspension losses due to vibrating
and bouncing of the bike increase".

I'm not sure of the publication date but the article references, among
others, a Australian Cyclist article published in March/April 2004, so
it is fairly recent. Over all they recommend a tire inflation pressure
sufficient to produce a "tire drop", actually compression under load,
of about 15%.

They state that "Tire pressures that correspond to 15% tire drop will
optimize your bike's performance and comfort on average road surfaces.
On very rough roads or unpaved roads, it may be useful to reduce the
pressure. On very smooth roads, increasing the pressure slightly
may improve the performance of your bike."

Their chart shows that a 23mm tire at 90 psi, a 25mm at 75 psi, a 28mm
at 65 psi and a 37mm at 40psi are optimum pressures to support a 88 lb
(40 kg.) wheel load with minimal tire losses.
--
cheers,

John B.

[Joe Riel]

Hardly. From the same page:

"Wide tires are generally used at low pressure. The larger air volume is
advantageous in that it absorbs road bumps and holes, but does not
suffer from higher rolling resistance, less puncture protection or low
tire wear."

The "larger air volume" has nothing to do it other than being a direct
result of a wider tire. That site isn't providing technical
information. To believe it because they posted it is foolish.

--
Joe Riel

[Frank Krygowski]

On 3/8/2016 6:51 PM, sms wrote:
> On 3/8/2016 3:18 PM, Roger Merriman wrote:
>> sms <scharf...@geemail.com> wrote:
>>
>>> On 3/8/2016 12:42 PM, Roger Merriman wrote:
>>>
>>> <snip>
>>>
>>>> I've not seen any science to back up low pressures or high pressures
>>>> helping puncture resistance.
>>>>
>>>> infact very sure it's old wifes tales.
>>>>
>>>> its all about construction.
>>>
>>> Construction is the major factor, but given the same construction a
>>> higher pressure tire is less likely to be punctured than a lower
>>> pressure tire.
>>>
>>> From the Schwalbe web site: "The following applies for the road: The
>>> higher the inflation pressure the lower the rolling resistance of the
>>> tire. The susceptibility to punctures is also lower with high pressure."
>>> <http://www.schwalbetires.com/tech_info/inflation_pressure>
>>>
>>> I would trust Schwalbe on this. There's no reason for them to lie about
>>> this.

That's pretty close to saying "It's on the Internet, so it must be
true!" Maybe it is, maybe it isn't. I'd like more explanation.

>>>
>> that looks like a old document TBH it doesn't refernce anything. maybe
>> they do have some facts to back this up, but with out them it is just
>> opinion.
>
> I don't think that one of the largest makers of tires has to reference
> anything or do a specific study when they make a statement as obvious
> and innocuous as that. It's not like you or I stating it. They _are_ the
> reference.
>
> And it's not an old document, it's currently on their site under the
> "Tech Info" section at <http://www.schwalbetires.com/tech_info>.
>
> It is true that tire construction is the major factor in puncture
> resistance, but all things being equal, a higher pressure tire will get
> fewer punctures.

Why, exactly? What's the mechanism?



--
- Frank Krygowski

[Frank Krygowski]

On 3/8/2016 6:35 PM, Phil W Lee wrote:
> Frank Krygowski <frkr...@sbcglobal.net> considered Tue, 8 Mar 2016

> The only obvious way is to include a dummy on the RR test, made from
> ballistic gel over a moderately realistic skeleton.
> The RR test should be run on an entire bicycle with the dummy rider of
> course, with both tyres taken into account. The rollers should be a
> large enough diameter to be a reasonable facsimile of an actual road
> surface if an actual flat surface is impossible to arrange.
> Test with various pressures, weights of dummy, and surface roughness
> as variables on each tyre type & size.
> A pattern should emerge fairly quickly to allow a smaller range of
> pressures to be used in each case.

I agree with the idea. The problem would be getting anyone to pay for it!


--
- Frank Krygowski

[Mike A Schwab]

On Sunday, March 6, 2016 at 2:57:12 PM UTC-6, avag...@gmail.com wrote:
> Never ridden a Dahon.
>
> MAY THE WIND BE WITH YOU

If you get a Bike Friday, Bike Friday will pay the entry fee if you enter a race using the Bike Friday.

P.S. 1. try shaving with a dry blade.
2. Wet the blade and try shaving again.
This is why you get a lot more flats in the rain.

[avag...@gmail.com]

never flatted in rain

????

is this common ?

what are we shaving ?

points ?

the post eludes my compre

Folder tires cannot be Continued 4 seasons at $8 a tire for Godless Atheists

So where' the ? what are they eating ? bits ?

[Tosspot]

On 09/03/16 02:51, John B. wrote:

<snip>

> Bike Quarterly published a tire loss study, authored by Jan Heine,
> which states in part that "At higher pressures, internal losses due to
> flexing of the casing decrease, but suspension losses due to vibrating
> and bouncing of the bike increase".

Is this;

http://www.bikequarterly.com/images/TireDrop.pdf

The article?

<snip>

[John B.]

On Wed, 9 Mar 2016 07:20:06 +0100, Tosspot <Frank...@gmail.com>
wrote:

Yup.
--
cheers,

John B.

[avag...@gmail.com]

Wet sanding carries sanded debris away from surface....

Or water film separates rubber from road as in extreme wuhwuhwuh extreme ...the woodpecker laughs n now cranes...wuhwuhwuh

Hydroplane ingredients

With clean surface paper bites surface.


Carrying that into the post...poss if we whisper , around a quantum element...the quantum crane stands honking outside my door...

A wider contact surface offers less friction than a narrow surface in the combined fluidity especially of air water and asphalt, a non mobile fluid, as quantum hydroplanning

......

Off course higher pressures in a narrow patch, causing flight or in a sub orbital trajectory, not engaging every asphalt crevasse rolled over elevates asphalt crack ledge impact friction to a bump level avoided with wider contact, less pressure.

We see that carried off in desert racing.
myriad crack impact levels bring narrow hi pressure tired vehicles to no speed in a minus null condition to gravity.

[AMuzi]

On 3/8/2016 5:35 PM, Phil W Lee wrote:
> Frank Krygowski <frkr...@sbcglobal.net> considered Tue, 8 Mar 2016
> 10:55:10 -0500 the perfect time to write:
>

> The only obvious way is to include a dummy on the RR test, made from
> ballistic gel over a moderately realistic skeleton.
> The RR test should be run on an entire bicycle with the dummy rider of
> course, with both tyres taken into account. The rollers should be a
> large enough diameter to be a reasonable facsimile of an actual road
> surface if an actual flat surface is impossible to arrange.
> Test with various pressures, weights of dummy, and surface roughness
> as variables on each tyre type & size.
> A pattern should emerge fairly quickly to allow a smaller range of
> pressures to be used in each case.
>

Jan Heine did some interesting work using a load of meat on
actual roads.

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

[sms]

On 3/8/2016 6:50 PM, Joe Riel wrote:

> The "larger air volume" has nothing to do it other than being a direct
> result of a wider tire. That site isn't providing technical
> information. To believe it because they posted it is foolish.

You have that backward. The wider tire is a direct result of the tire
being designed for larger air volume.

Wider tires, which also happen to have a larger outer diameter, provide
better suspension by virtue of the larger volume of air at lower pressure.

Vehicle tires take advantage of this as well. There's no real reason for
the size of the sidewalls on vehicle tires other than the suspension
effect. Now some vehicles have moved to low-profile tires but they've
had to compensate with larger springs and shocks because of the
inherently rougher ride. The low profile tires increase the likelihood
of wheel damage and don't do well in snow.

[Joe Riel]

sms <scharf...@geemail.com> writes:

> On 3/8/2016 6:50 PM, Joe Riel wrote:
>
>> The "larger air volume" has nothing to do it other than being a direct
>> result of a wider tire. That site isn't providing technical
>> information. To believe it because they posted it is foolish.
>
> You have that backward. The wider tire is a direct result of the tire
> being designed for larger air volume.

> Wider tires, which also happen to have a larger outer diameter,
> provide better suspension by virtue of the larger volume of air at
> lower pressure.
>
> Vehicle tires take advantage of this as well. There's no real reason
> for the size of the sidewalls on vehicle tires other than the
> suspension effect.

Huh? It's the suspension effect that is the whole point.
It's the sidewall, not the volume of air that is the issue.
Do you imagine that adding a reservoir of air in a central
chamber would change the stiffness of a tire?

--
Joe Riel

[Frank Krygowski]

Yes, on actual roads, and on an asphalt Soapbox Derby track, IIRC.


--
- Frank Krygowski

[sms]

Deflate your bike tires and check the stiffness and get back to us.

[Joe Riel]

Volume and pressure are not the same thing.

--
Joe Riel

[Rolf Mantel]

Yes I do, in fact it's quite simple: at each point in time, the dynamic
forces on the tire surface can be calculated.
As air distribution is significantly faster than movement of
macro-masses, we are allowed the simplifying assumption that air
pressure is uniform.

Therefore, at each point in time, the force exerted to the inside of the
tire by air pressure is equal to the force exerted to the outside of the
tire by mechanical causes (vehicle weight, dynamic mass movement).
So any dynamics on the vehicle cause an instant change of air pressure
inside the tire, which in turn changes the tire volume by a certain
percentage.
So an additional air reservoir of the tire causes a significant impact
on the tire dynamics (without careful notation of the relevant equations
I do not dare decide whether this impact would be beneficial or
detrimental to rolling resistance or to comfort).

Rolf

[Joe Riel]

The change in pressure in small. The change in tire volume due to a
change in pressure is small. The combined effect is tiny.

> So an additional air reservoir of the tire causes a significant impact
> on the tire dynamics (without careful notation of the relevant
> equations I do not dare decide whether this impact would be beneficial
> or detrimental to rolling resistance or to comfort).

The real effect is through the sidewall flexing. That's why, for
comfort, riders prefer a tire with a more flexible casing.

--
Joe Riel

[sms]

I doubt if the volume of air has an impact on rolling resistance, beyond
the fact that you need a larger volume of air to achieve the same
pressure for a larger tire than a smaller tire.

[Radey Shouman]

Interesting thought experiment. I would expect a rigid reservoir to
affect the stiffness of a tire.

The tire "spring" is a result of the relationship between pressure and
volume -- when the volume is decreased by deforming the tire the
pressure increases, tending to restore the shape of the tire.

Approximately,
P = nRT/V
dP/dV = -(nRT/V^2) ~ <spring constant>

If you increase V, |dP/dV| will decrease, and the tire will act as
though it were inflated to a lower pressure. Pumping air into the tire
increases n, and thus |dP/dV|.

--

[Joe Riel]

This is fairly easy to test. Replace most of the air in the tube
with water, which is essentially incompressible. I've ridden such
a tire out of necessity---if a tube has a small leak, water generally
won't leak out. My recollection is that I could not tell the difference
(this was on the rear wheel; a weight difference is easily detectable
in the front).

In your computation you need to scale that by dV/dx (change in volume
due to compression of tire). That is a small number.

--
Joe Riel

[Frank Krygowski]

I think the change in air volume and change in pressure is negligible
for our typical bike tires.

I just put a gauge on a front tire on one bike. I got 70 psi unloaded.
Then I put most of my weight on that wheel. The gauge didn't budge.
Maybe a more sensitive gauge would show some change, but I can normally
read this one to 1 psi.

--
- Frank Krygowski

[James]

I asked Schwalbe this question;

"From your site, "The susceptibility to punctures is also lower with
high pressure."
<http://www.schwalbetires.com/tech_info/inflation_pressure#important>

That is true of pinch flats, but are you suggesting it is true
generally? In other words, are tires less susceptible to punctures from
glass or other penetrating debris, with higher pressure?"

And the reply came;

"James, that sentence would be a generalization in regards to tire
inflation and tire wear, and shouldn’t be assumed that it would cover
all variables when it comes to adjusting to road conditions. I think the
best defense for glass and other debris is to avoid it.

Cheers,
Luke McMurphy | Customer Service / Tech Support
SCHWALBE North America
USA | Canada
"

So no evidence.

--
JS

[Roger Merriman]

see James reply.

Roger Merriman

[Radey Shouman]

Did you fill the tire to a measured pressure, or did you do it by
feel?

> In your computation you need to scale that by dV/dx (change in volume
> due to compression of tire). That is a small number.

True, but it's the only explanation for *any* effect of tire pressure on
suspension. The structure of the sidewalls remains the same regardless
of pressure.

--

[Radey Shouman]

Follow that argument to its logical conclusion and you will say that
tire pressure has no effect on ride quality. What other mechanism is
there for *any* effect of tire pressure?

> I just put a gauge on a front tire on one bike. I got 70 psi
> unloaded. Then I put most of my weight on that wheel. The gauge
> didn't budge. Maybe a more sensitive gauge would show some change, but
> I can normally read this one to 1 psi.

And yet pumping the tire up makes a difference, how can you explain that?

--

[avag...@gmail.com]

?

more contact more width less pressure gives more flats

shorter sidewalls with wider tires gives max entry response with more subjective slide control...lateral force experience.

more tread less sipe gives greater grip

recommended air pressure is designed into the sidewall so you can read it.

less gives more grip on loose surfaces

for most drivers more pressure gives more grip on hard surfaces with a HARSHER ride quality . This is often a subjective experience that is 'control' is experienced as performance.

wider tires suck in the snow, wider tires with deep grooves run well in water but not extra wide.

air volume ? an ideal tire has minimal sidewall height with low ride harshness.

Schwalbe as a German Co. niched with tires designed for cobbled streets. Sometimes as the Euro 29" tire.

max mileage tires are often found in other cars trunks and in the recycle yard.

same for low noise tires.

tires without treads are found on church bus tires in the S. US


add one ? not over 25 wrods

[Joe Riel]

Not sure what you are asking. I filled the tube with water, added air
pressure, then rode home.

>> In your computation you need to scale that by dV/dx (change in volume
>> due to compression of tire). That is a small number.
>
> True, but it's the only explanation for *any* effect of tire pressure on
> suspension. The structure of the sidewalls remains the same regardless
> of pressure.

Then why does sidewall stiffness make a difference?

Try doing the experiment I described. Measure the drop
vs load with and without the tube filled mostly with water.
I'll do it when I get some time.

--
Joe Riel

[Radey Shouman]

How did you determine that the tire pressure was the usual? If you just
felt the tire, and it felt "normal", then you have no way of knowing
that tire pressure actually was.

>>> In your computation you need to scale that by dV/dx (change in volume
>>> due to compression of tire). That is a small number.
>>
>> True, but it's the only explanation for *any* effect of tire pressure on
>> suspension. The structure of the sidewalls remains the same regardless
>> of pressure.
>
> Then why does sidewall stiffness make a difference?

There is a purely mechanical support provided by the sidewall, but
without pressure tires are pretty useless.

> Try doing the experiment I described. Measure the drop
> vs load with and without the tube filled mostly with water.
> I'll do it when I get some time.

I'm not sure how to easily fill a tube with water. My tubes have
non-removable Presta cores.


--

[AMuzi]

The same way The Ancients shot milk into tubulars to clot a
slow leak. Draw water into your pump, press onto the valve
and pump it in.

[Frank Krygowski]

The tire pressure definitely has an effect. We can discuss. What I'm
saying is that there is negligible _change_ in tire pressure with
typical tire deflections.

>> I just put a gauge on a front tire on one bike. I got 70 psi
>> unloaded. Then I put most of my weight on that wheel. The gauge
>> didn't budge. Maybe a more sensitive gauge would show some change, but
>> I can normally read this one to 1 psi.
>
> And yet pumping the tire up makes a difference, how can you explain that?

First, don't lose sight of the fact that I measured no change in
pressure when I put nearly all my weight on the bike's front wheel.
Try repeating my experiment, and see if you get different results. I
don't think you will.

Now, to explain the difference between low pressure and high pressure
in a given tire:

Whether for steady loads or dynamic loads, the vertical load downward on
the wheel & tire has to be balanced by an upward force from the ground
on the tire. The upward force acts on the area of the contact patch.
To get the basics understood, we can assume (or pretend?) a tire with
zero wall stiffness - something like a common latex balloon.

If that theoretical tire has a pressure of 50 psi and a load of 100
pounds, the tire will deform until the area of the contact patch is 2
square inches. Obviously, that will require a certain amount of
vertical displacement.

OTOH, if we raise the tire pressure to 100 psi, for that same tire to
support 100 pounds, it needs to deform only until the contact patch is
one square inch. That requires less vertical displacement.

So a higher pressure tire is stiffer against vertical loads. No change
in pressure with change in volume is necessary to explain this.

--
- Frank Krygowski

[Joe Riel]

Yes, but it is the mechanical properties of the sidewall that determine
the stiffness for a given pressure. The volume of the compressible gas
inside the tube has little to do with it. If it did, then filling the
tube half full of water should stiffen it up by four times (nRT/V^2).

>
>> Try doing the experiment I described. Measure the drop
>> vs load with and without the tube filled mostly with water.
>> I'll do it when I get some time.
>
> I'm not sure how to easily fill a tube with water. My tubes have
> non-removable Presta cores.

It isn't hard. Use a frame pump that you can disassemble. Position
valve at top of wheel. Remove the plunger from the pump, fill the body
with water, insert plunger, press. Repeat until full.

If you do this, be sure to dry the pump thoroughly after use.
I'll use on old pump I don't care about.

--
Joe Riel

[James]

There have been studies that reveal the damping effect of a human on a
bike. I found some while looking in to vibration isolation mounts for a
camera.

--
JS

[Radey Shouman]

And you just squeeze it out? I'll consider it.

--

[Radey Shouman]

Which is what led me to ask what you kept constant in your experiment.
Did you measure the pressure? I think the factor should be 2 times,
since n would be halved at the same pressure.

I believe that even a perfectly flexible sidewall would still function in a tire.

>>> Try doing the experiment I described. Measure the drop
>>> vs load with and without the tube filled mostly with water.
>>> I'll do it when I get some time.
>>
>> I'm not sure how to easily fill a tube with water. My tubes have
>> non-removable Presta cores.
>
> It isn't hard. Use a frame pump that you can disassemble. Position
> valve at top of wheel. Remove the plunger from the pump, fill the body
> with water, insert plunger, press. Repeat until full.
>
> If you do this, be sure to dry the pump thoroughly after use.
> I'll use on old pump I don't care about.

I might just try it.

--

[Radey Shouman]

Sorry, you haven't explained a thing. Please explain the difference in
ride quality between a tire at low pressure and a tire at high pressure.
Would the hypothetical zero stiffness tire show different ride qualities
at different pressures?

I submit that the difference is in the restoring force provided by the
tire against (high frequency, low amplitude) deflections. Essentially
the difference is in the spring constant of the inflated tire -- I
suspect the damping term remains more or less the same regardless of
pressure, since there is very little actual air flow.

--

[Joe Riel]

Good point, I missed that.

> I believe that even a perfectly flexible sidewall would still function
> in a tire.

Yes and no. The desired flexibility is in bending, not in tension. An
inner tube, by itself, would not work well. The support comes from the
compression of the pretensioned sidewall, analagous to compression of
the pretensioned spokes.

>>>> Try doing the experiment I described. Measure the drop
>>>> vs load with and without the tube filled mostly with water.
>>>> I'll do it when I get some time.
>>>
>>> I'm not sure how to easily fill a tube with water. My tubes have
>>> non-removable Presta cores.
>>
>> It isn't hard. Use a frame pump that you can disassemble. Position
>> valve at top of wheel. Remove the plunger from the pump, fill the body
>> with water, insert plunger, press. Repeat until full.
>>
>> If you do this, be sure to dry the pump thoroughly after use.
>> I'll use on old pump I don't care about.
>
> I might just try it.

The tricky part is accuratenly measuring the effective vertical
compliance. The drop itself is easily measured, though getting it
accurately with what I have is not so easy. I'm hoping to create
plots of drop vs load at various starting pressures and various
amounts of water.

--
Joe Riel

[Radey Shouman]

An inner tube would not work because the surface area of the tube is not
constant, so the volume can too easily change. That is the main
difference between tire and tube, not any sort of mechanical stiffness
independent of inflation.

>>>>> Try doing the experiment I described. Measure the drop
>>>>> vs load with and without the tube filled mostly with water.
>>>>> I'll do it when I get some time.
>>>>
>>>> I'm not sure how to easily fill a tube with water. My tubes have
>>>> non-removable Presta cores.
>>>
>>> It isn't hard. Use a frame pump that you can disassemble. Position
>>> valve at top of wheel. Remove the plunger from the pump, fill the body
>>> with water, insert plunger, press. Repeat until full.
>>>
>>> If you do this, be sure to dry the pump thoroughly after use.
>>> I'll use on old pump I don't care about.
>>
>> I might just try it.
>
> The tricky part is accuratenly measuring the effective vertical
> compliance. The drop itself is easily measured, though getting it
> accurately with what I have is not so easy. I'm hoping to create
> plots of drop vs load at various starting pressures and various
> amounts of water.

That would certainly be interesting to me.

--

[Frank Krygowski]

Or perhaps you just didn't get the explanation? Did you understand why,
if the pressure is half as great, the contact patch must be twice as
great?

> Please explain the difference in
> ride quality between a tire at low pressure and a tire at high pressure.
> Would the hypothetical zero stiffness tire show different ride qualities
> at different pressures?

Yes. Re-read what I wrote above. Here's more.

If we measure spring constant in the usual way, a tire with higher
pressure will have a higher spring constant than that same tire with
lower pressures.

The geometry of a toroid is fairly complicated. I won't attempt to
calculate the amount of vertical movement necessary to produce a contact
patch of 1 square inch and 2 square inches. (I suspect that Joe would do
a better job than I.)

But it should be obvious that it does take more downward squashing of
the tire to double the contact area. In other words, it takes more
downward movement to support a given load if the tire has more pressure.

Again, this is simple F = P * A. It does not rely on any increase in
pressure caused by a decrease in volume. The volume change is too small
anyway.

> I submit that the difference is in the restoring force provided by the
> tire against (high frequency, low amplitude) deflections. Essentially
> the difference is in the spring constant of the inflated tire -- I
> suspect the damping term remains more or less the same regardless of
> pressure, since there is very little actual air flow.

We agree that the difference is the effective spring constant. Our
disagreement is just about whether a change in pressure is present, or
necessary, or significant.

--
- Frank Krygowski

[Frank Krygowski]

OOPS! Typo! I meant, it takes more downward movement to support a
given load if the tire has LESS pressure.

[Joe Riel]

Here's a crude approximation. Let s be the sinkage of the tire onto a
flat surface. Assume uniform pressure across the contact area and
assume the shape is an ellipse with its major radii given by a truncated
torus. For s small the area is approximately

A = pi*sqrt((2*s*r+s^2)*(2*s*R+s^2))

where
r = minor radius of torus
R = major radius of torus

For s small wrt r

df/ds = p*dA/ds ~ pi*(2*sqrt(r*R) + s*(R/r))

with
f = load on wheel
p = tire pressure

The first term (constant) dominates for typical road bike tires. This
means that, for this simple approximation, the stiffness is independent
of the load for a constant pressure. It's not hard to show that the
pressure change is tiny. More significantly, the stiffness is directly
proportional to the tire pressure.

--
Joe Riel

[Joe Riel]

I stated that the pressure change is tiny. Let's put an upper bound
on it using this approximation. The volume change in the tire
is less than s*A. The volume of a torus

V = (pi*r^2)*(2*pi*R)

For small s

A*s/V ~ 1/pi*(s/r)*sqrt((s/r)*(s/R))

Using 15% sinkage, i.e. s/(2*r) = 15% and putting in typical road
bike tire sizes I get

A*s/V ~ 0.005.

That is, the decrease in volume is less than 0.5%. So pressure
increase is less than 0.5%. That's negligible.

--
Joe Riel

[Rolf Mantel]

Am 10.03.2016 um 04:43 schrieb Frank Krygowski:

> The geometry of a toroid is fairly complicated. I won't attempt to
> calculate the amount of vertical movement necessary to produce a contact
> patch of 1 square inch and 2 square inches. (I suspect that Joe would do
> a better job than I.)
>
> But it should be obvious that it does take more downward squashing of
> the tire to double the contact area. In other words, it takes more
> downward movement to support a given load if the tire has more pressure.

A simple approximation is by using a car-type tire geometry, i.e. a tire
with constant width. With a tire of 1/2in width, a contact patch of 1
square inch would correspond to a contact length of 2 inches, a contact
patch of 2 square inches would correspond to a contact length of 4 inches.

So the angle of the half contact patch with a 28in wheel is given by sin
alpha1 = 1/28 (alpha1 = 2 degrees) or sin alpha2 = 1/14 (alpha2 = 4
degrees), and the sink-in is given by 14 in * cos (alpha1) or 0.2mm and
14in * cos (alpha2) or 0.8mm.

[Frank Krygowski]

Thanks. I knew I could count on you to do the math!

--
- Frank Krygowski

[Joe Riel]

I don't put much faith in the truncated torus as a good approximation;
in reality the tire will bulge. Depending on the tire construction that
could increase, rather than decrease, the volume, however, I presume the
latter is more common. The best test is a simple measurement, which
you've done and confirmed that the change is small.

--
Joe Riel

[Andre Jute]

On Thursday, March 10, 2016 at 3:43:55 AM UTC, Frank Krygowski wrote:
> On 3/9/2016 8:05 PM, Radey Shouman wrote:
> >
> > Sorry, you haven't explained a thing.
>
> Or perhaps you just didn't get the explanation? Did you understand why,
> if the pressure is half as great, the contact patch must be twice as
> great?

Radey is right (hurrah! savour the moment!), Franki-boy. You haven't explained shit. Maybe in an ivory tower, where the tyre containing your notional pressure is a thin skein infinitely and equally malleable in all directions, and if the experiment were conducted in outer space distant from any evidence of gravity, and the "road" was glass-smooth, you could achieve that outcome.

In real life your explanation is crap. Tyres are specifically designed to be differentially flexible in some directions and as little as possible in others. Cut through a Schwalbe tyre of the type we're discussing and open your eyes, at which point you will suddenly discover different materials of different thicknesses in the construction of the carcass and covering. Even that rubber that to you looks all the same is very different in different places.

In particular, today the art of tyre design is in the sidewall, where most of the flex is permitted/arranged/controlled for whatever roadholding/handling/comfort/durability parameters are dialed in to the design team by the marketing department. In my handbook for (very) upmarket hotrodders, Designing and Constructing Special Cars (American edition published by Bentley, Boston), I show the deformation of parts of a tyre under stress, without scales because the point I want to make is the complexity of the response, which in each case is an S on a cross with negative as well as positive quadrants. In no case that I ever observed, or heard or read about, was the contact patch directly proportional to the change in pressure.

I'm really at a loss to understand why even you, Krygwoski, should believe something so childishly contrary to common experience, so bizarre.

Andre Jute
Going back to the Iditarod. Mushers make sense.

[John B.]

On Thu, 10 Mar 2016 02:53:41 +0000, Phil W Lee <ph...@lee-family.me.uk>
wrote:

>John B. <slocom...@gmail.xyz> considered Wed, 09 Mar 2016 08:51:39
>+0700 the perfect time to write:

>
>>On Tue, 8 Mar 2016 10:55:10 -0500, Frank Krygowski
>><frkr...@sbcglobal.net> wrote:
>>
>>>On 3/8/2016 1:26 AM, Tosspot wrote:
>>>>
>>>> But the internet saves the day!
>>>>
>>>> http://www.bicyclerollingresistance.com/
>>>>
>>>
>>>I'm a bit skeptical of their values, because of the nature of their
>>>test. Yes, it's the typical RR test, running the wheel and tire on a
>>>rotating drum. But I that measures only the losses within the tire
>>>rubber, not the closely related phenomenon of suspension losses in the
>>>mass of the bike+rider. Wider tires are better at reducing those latter
>>>losses.
>>>
>>>Jobst used to say those losses are not tire losses, or something
>>>similar. But they are the precise reason we use pneumatics in the first
>>>place. I think they need to be somehow modeled and included.
>>

>>Bike Quarterly published a tire loss study, authored by Jan Heine,
>>which states in part that "At higher pressures, internal losses due to
>>flexing of the casing decrease, but suspension losses due to vibrating
>>and bouncing of the bike increase".
>>
>>I'm not sure of the publication date but the article references, among
>>others, a Australian Cyclist article published in March/April 2004, so
>>it is fairly recent. Over all they recommend a tire inflation pressure
>>sufficient to produce a "tire drop", actually compression under load,
>>of about 15%.
>>
>>They state that "Tire pressures that correspond to 15% tire drop will
>>optimize your bike's performance and comfort on average road surfaces.
>>On very rough roads or unpaved roads, it may be useful to reduce the
>>pressure. On very smooth roads, increasing the pressure slightly
>>may improve the performance of your bike."
>>
>>Their chart shows that a 23mm tire at 90 psi, a 25mm at 75 psi, a 28mm
>>at 65 psi and a 37mm at 40psi are optimum pressures to support a 88 lb
>>(40 kg.) wheel load with minimal tire losses.
>
>That seems reasonable, although obviously there is a limit to how much
>you can lower pressures to cope with a rough road before snakebite
>punctures become a problem. If the road is that rough, you need a
>wider tyre (or just to put up with the discomfort and inefficiency of
>higher than optimum pressures).

The article seems to say that the 15% compression is ideal but if the
roads are rough you might try "slightly" less pressure.

If you are riding something heavier then a conventional bike then you
can easily determine the weight of the loaded bike, with crew aboard,
and start from the "wheel weight" side of the chart to work out what
size tire and tire pressure in optimum.

>They use a very coarse "surface dressing" here (I think in the US it's
>known as chip and seal - here it's more commonly referred to outside
>the world of road workers as "spray and scatter". The coarseness of
>the stone chips means 28mm is pretty much a minimum except for very
>lightweight riders, or those prepared to put up with considerable
>discomfort and additional effort.

The article doesn't try to suggest what size tire is used, It simply
provides a formula for calculating what they say is the optimum tire
pressure for various sizes of tire in order to obtain the least "tire
losses".

>On roads which have not been treated in that way since being
>completely re-laid, the effort required is very much less, and
>narrower tyres with higher pressures are more efficient, and
>comfortable enough.
>For fully loaded touring, I'd not want to use anything less than 32mm,
>and (depending on load & expected terrain) up to around 42mm. On my
>tourer, which didn't get heavily loaded very often (just occasional
>heavy shopping) I had 28mm both ends, and on my recumbent, 37mm is my
>preference, although for some reason, it has a 32mm on the back (it
>was on there when I got it, and I never managed to ride enough to wear
>it out before losing the capability to ride at all - I really should
>change it before selling the bike though). Of course, the 'bent is a
>bit different, as you can't stand on the pedals and use your legs as
>shock absorbers (or if you can, you have a bright future as a circus
>performer or on a monetised Youtube channel).
>Of course, many (possibly even most) riders with sporting pretensions
>tend to ride narrower tyres than are ideal for them, because that
>looks more like what Lance/Froome/Bradley/Cav* uses.
>
>*Insert other preferred racing idol as appropriate.
--
cheers,

John B.

[sms]

I installed the Marathon Plus tires today. The installation did require
the use of tire levers, both to get the old Marathons off, and to get
the new Marathon Pluses off. I've had other tires that were more
difficult, but these are definitely very tight.

Of course "there's always something."

I noticed that the right side axle nut on the rear hub was cracked. This
was very bad news as I soon learned. It's an SRAM 3 x 7 rear hub with a
10.5mm x 26 TPI 6.75mm thick nut. There are very hard to find. No bike
shops I visited or called had any. One shop gave me an old SRAM hub with
two hub nuts of the proper threading, but the outer diameter is 17mm,
and the outer diameter of the nut I needed is 15mm since it goes into
the SRAM shift mechanism.

According to Sheldon "The axle threading of most SRAM internal-gear hubs
is unusual, 10.5mm x 26 TPI, but close enough to that of many
Sturmey-Archer hubs (13/32 x 26 TPI) that Sturmey-Archer axle nuts are
usable in a pinch." I did find one shop that has some of the
Sturmey-Archer axle nuts so I'll go over there tomorrow and check those
out. I also e-mailed a famous shop in Wisconsin whose web site mentions
that they carry SRAM axle nuts, whose owner sometimes posts in this
newsgroup.

[sms]

On 3/10/2016 5:10 PM, sms wrote:
> I installed the Marathon Plus tires today. The installation did require
> the use of tire levers, both to get the old Marathons off, and to get
> the new Marathon Pluses off.

Oops, s.b. "to get the new Maratohon Pluses on."

[jbeattie]

They did? I can only imagine the stench three days later. When I was a young Ancient, I just threw on a spare and fixed the leaking tire. I was lactose intolerant.

-- Jay Beattie.

[AMuzi]

I can remember smelling it when a tire burst ahead of me on
a group ride. Yecchh.

Found it!
http://yarchive.net/bike/tire_goo.html

Mr Brandt:
"When I was riding my last Clement tubulars, that had poor
stitch protectors that caused many pin hole leaks, my tires
kept going
flat. Knowing about the ability of the butterfat in milk to
plug such
holes, I poured a few ounces of milk, from a dairy on the
Klausen pass
in Switzerland, into my tire pump and pumped it into my
tires. This
solved my problem, but a few weeks later, back home, while
riding to
Santa Cruz with a bunch of bikies sitting on my wheel, I had
a rear
blowout and sprayed them with putrid milk, while I had a
hard time
controlling the bike as it slid around on the flat tubular
like ice."

[sms]

On 3/10/2016 5:10 PM, sms wrote:

> I installed the Marathon Plus tires today. The installation did require
> the use of tire levers, both to get the old Marathons off, and to get
> the new Marathon Pluses off. I've had other tires that were more
> difficult, but these are definitely very tight.

Wow, those Marathon Plus tires are quite nice. Much nicer ride than the
old OEM Marathon non-Plus tires of the same size. If they really do
prevent most flats then they will be well worth the high cost.

Glad I did not opt for wider tires because I would have had to remove
the fenders on the folder had they been much wider. Probably could have
fit 1.5" instead of 1.35" but those were rated at much lower pressure
and as all the tire discussion recently has shown, you really want to be
at as high a pressure as possible.

[Radey Shouman]

Perhaps I understood how to calculate the area of the contact patch, but
not how that explains a thing about the dynamic behavior of a tire?

Having thought about it, I agree that the effect of tire volume on the
effective spring constant is secondary.

When a tire is compressed, work is done on the air inside:

w = integral (P dV)

Work is done only by a decrease in the tire volume.

If the process is adiabatic (almost true) and the tire sidewall is
perfectly flexible in bending but inflexible in stretching (not that
true), then the work will show up in increased enthalpy of the air
in the tire, and hence in a (slightly) higher temperature.

delta H = Cp delta T

Volume decreases, temperature increases slightly, hence pressure *must*
increase. Tire stiffness does depend mostly on pressure, so a tire
should become stiffer as it is compressed, but this effect may be quite
small.

When the tire recovers, it does work on its surroundings, volume
increases ...

It's not immediately clear to me exactly how volume relates to either
tire height or contact area, but plainly decreasing volume is associated
with decreasing height and increasing contact area.

To get back to the original question, I don't think it's obvious at all
that adding a hypothetical fixed volume reservoir to a tire would not
affect the ride quality.

On the question of whether differences in pressure are significant, I
have to question the test of measuring the pressure difference made by
sitting on the bicycle -- I suspect the actual forces involved in
questions of ride quality are much larger.

For example, how much static weight would you have to pile on your
bicycle in order to reproduce a pinch flat? I have no idea, but I'm
reasonably sure some heavy equipment would be involved.

[Radey Shouman]

Andre Jute <fiul...@yahoo.com> writes:

> On Thursday, March 10, 2016 at 3:43:55 AM UTC, Frank Krygowski wrote:
>> On 3/9/2016 8:05 PM, Radey Shouman wrote:
>> >
>> > Sorry, you haven't explained a thing.
>>
>> Or perhaps you just didn't get the explanation? Did you understand why,
>> if the pressure is half as great, the contact patch must be twice as
>> great?
>
> Radey is right (hurrah! savour the moment!), Franki-boy. You haven't
> explained shit. Maybe in an ivory tower, where the tyre containing
> your notional pressure is a thin skein infinitely and equally
> malleable in all directions, and if the experiment were conducted in
> outer space distant from any evidence of gravity, and the "road" was
> glass-smooth, you could achieve that outcome.
>

Easy, Andre, you'll do your heart a mischief.

[Tosspot]

On 11/03/16 02:10, sms wrote:
> I installed the Marathon Plus tires today. The installation did require
> the use of tire levers, both to get the old Marathons off, and to get
> the new Marathon Pluses off. I've had other tires that were more
> difficult, but these are definitely very tight.

I've never managed to get a tyre off without levers, but if I'm using
them to get a tyre on it's laziness.

[sms]

Wider tires, lower pressure, larger diameter tires, are usually not a
problem. The combination of small diameter, narrow width, and
high-pressure combine to make it more difficult. You want high pressure
tires to fit pretty tightly on the rim.

[James]

On 17/03/16 02:10, Radey Shouman wrote:

> For example, how much static weight would you have to pile on your
> bicycle in order to reproduce a pinch flat? I have no idea, but I'm
> reasonably sure some heavy equipment would be involved.
>

I disagree. Most times you get a pinch flat it occurs on an edge of
some obstacle, like the edge of a pot hole for example.

On the closest bike to me, the front tyre 23mm is inflated to about
85-90psi. I took a piece of timber that is basically a square section,
and was able to *easily* press down one edge into the tyre until I could
feel it had touched the rim. I probably pushed down with only 20-30kg.

--
JS

[Radey Shouman]

James <james.e...@gmail.com> writes:

> On 17/03/16 02:10, Radey Shouman wrote:
>
>> For example, how much static weight would you have to pile on your
>> bicycle in order to reproduce a pinch flat? I have no idea, but I'm
>> reasonably sure some heavy equipment would be involved.
>>
>
> I disagree. Most times you get a pinch flat it occurs on an edge of
> some obstacle, like the edge of a pot hole for example.

So put such an edge under the tire.

> On the closest bike to me, the front tyre 23mm is inflated to about
> 85-90psi. I took a piece of timber that is basically a square
> section, and was able to *easily* press down one edge into the tyre
> until I could feel it had touched the rim. I probably pushed down
> with only 20-30kg.

You need considerable force to put a hole in the tube, though.

--

[James]

I am not about to try, but I doubt it is as much as you might be imagining.

--
JS

[Radey Shouman]

If you put a naked tube on a curb edge, and stand on it, I doubt very
much that you'll get a flat. A hammer would work, but the accelerations
there are orders of magnitude higher.

--