Lower pressure tyres vs suspension seat post??

Michael Press

In article <4852f59a.2266203@news20.forteinc.com>,
go.spam@somewhere.else (Jose) wrote:

> On Thu, 12 Jun 2008 07:05:41 -0700 (PDT), landotter
> <landotter@gmail.com> wrote:
>
> >Tires and suspension posts vary wildly in design, so one can't make a
> >blanket statement. For road riding, a 35mm+wide smooth tread tire with
> >a fine supple casing at 80psi (5 bar) or less is probably the least
> >fussy way to get a nice ride.
>
> I've been using Maxis Detonator 700x25. Around town, I need to drop
> the pressure to 70 psi. Away from town, I'm fairly confortable at 90
> psi (+ the suspension seat post I use).
>
>
>
> > Tires with rigid casings will be more
> >durable--but you'll feel a lot more road noise in your butt and hands--
> >road noise that even a suspension post won't be able to absorb.
>
> How do you know if a tyre is less rigid than another (before trying
> both)? Just by looking at the tpi count? I get the feeling that the
> lower tpi count tyres are smoother - could I be mistaken?

A true high thread per inch side wall is thinner than
lower tpi. Thinner side wall means less power dissipated
flexing the side walls.

Before you buy you handle the tire flex the sidewall with
your hands. Check the tread thickness. Flex the tread.

> >> Of the non suspension seatposts, are they all equally "bad" at
> >> absorbing shock and vibration?
>
> OK, so why are so many people enthusiated about carbon and titanium
> seat post? I understand that carbon can be made more flexible, but on
> such a short extension, I have doubts. Titanium - besides
> outrageously expensive - I had the idea was more rigid than
> aluminum...

--
Michael Press

Tom Kunich

"Jose" <go.spam@somewhere.else> wrote in message
news:4853a146.869609@news20.forteinc.com...
> On Fri, 13 Jun 2008 16:07:31 -0700, "Tom Kunich" <cyclintom@yahoo.
>
>>But leather saddles can stretch and shape themselves to your posterior and
>>can actually get comfortable. That's why you see some people who have
>>spent
>>a small fortune on carbon fiber bikes mounting a 3 lb leather saddle to
>>it.
>
> Good point! I can imagine that after a while a leather sadle would
> accomadate my seat bones quite well. However, I imagine that would
> make me "sink" in the sadle and get numb you know where ;-P

It is possible for a leather saddle to break-in badly and then not work
well. But most of them do not apply pressure to the wrong places. My Brooks
B-17 was fairly comfortable right from the start, but after 500 miles it was
sort of surprising to me that it actually felt good to sit on. I've never
known that sensation before. Of course I always used plastic saddles too.

Jose

On Sat, 14 Jun 2008 04:41:17 -0700 (PDT), Art Harris
<n2ah@hotmail.com> wrote:


Hi Art


>> Would the wider tyre:
>> 1) absorb shock equally well, if pumped at 100, and 80 psi,
>> respectivelly?
>
>A wider tire should get _less_ pressure. For example, a 700x28 at 70
>psi would have less rolling resistance and less chance of pinch
>flatting than a 700x25.

On a 15 mm wide rim, I doubt it would pinch flat. Anyway, 700x28
seems a better all round choice - it should have better performance at
70 psi around town, and still take 90 or 100 psi for real road use,
without bursting.


>Optimum tire pressure depends on tire width, rider weight, and your
>preference for either comfort or lowest rolling resistance. It's a
>trade-off.

Yes, I think I understand that - my present 700x25 Maxis Detonator, at
around 66 tpi, is significantly smoother than the 700x25 Continental
UltraGatorSkin I used before, at the same pressures


>Note that some tires aren't really the width they're advertised as. A
>tire marked 700x28 might actually measure 25 or 26mm on a rim.

That sucks! Anyway, since I can't find any 700x28 around here, I'll
have to order through Internet, and rely on thread counts, recommend
pressures, etc.


>In your case, I'd recommend a true 700x28 at about 85 psi rear and 80
>psi front (assuming you're not a heavyweight). If comfort is your
>primary goal, you might need a bike that takes 700x32 tires.

I'm not sure if my bike can take 700x32 tyres, but among the 700x28,
some are more confortable (albeit less performant) than others ;-)


Best,
Jose

Jose

On Sat, 14 Jun 2008 11:29:58 -0700, Michael Press <rubrum@pacbell.net>
wrote:

Hi Michael,

>A good 25 mm wide tire
>can be built with 127 thread per inch casing. A 28 mm wide
>is always built with 66 thread per inch casing.

Vittoria Rubino Pro and Pro Tech, 700x28, 120 tpi, 70-115 psi, 230-250
gr.

The ContinentalUltraGatorSkin 700x28, and Panaracer Pasela 700x28 also
come to mind. At the least the Continental has a hight thread count -
as always...


> This difference
>alone will negate the advantage in width of the 28 mm wide tire.

Not sure what you mean here. I've learned that lower tpi equals more
confort but less performance. Am I missing something?

Aramid vs steel bead: besides a slight weigh diference, what
perceivable diferences do they have?


>I find 25 mm wide tires to be comfortable.
>If you want wide tires for comfort, then you need a new frame.

No, I don't think I want a full suspension frame ;-)

Best,
Jose

Art Harris

Jose wrote:

> At the least the Continental has a hight thread count -
> as always...
>

Continental counts the threads in each ply. It's not a fair
comparison.


>
> I've learned that lower tpi equals more
> confort but less performance. Am I missing something?
>

A high tpi casing is more flexible and has lower rolling resistance.
If anything, it may be more comfortable.


>
> Aramid vs steel bead: besides a slight weigh diference, what
> perceivable diferences do they have?
>

None, except they're easier to fold and carry as a spare.

Art Harris

Michael Press

In article <485afb08.10120296@news20.forteinc.com>,
go.spam@somewhere.else (Jose) wrote:

> On Sat, 14 Jun 2008 11:29:58 -0700, Michael Press <rubrum@pacbell.net>
> wrote:
>
> Hi Michael,
>
> >A good 25 mm wide tire
> >can be built with 127 thread per inch casing. A 28 mm wide
> >is always built with 66 thread per inch casing.
>
> Vittoria Rubino Pro and Pro Tech, 700x28, 120 tpi, 70-115 psi, 230-250
> gr.

I am not saying that Vittoria does, but some companies
fudge the advertised thread per inch. The goal is to
make the sidewalls thin so as to decrease the power
dissipated flexing the sidewalls and the tread.
Some companies have count all the threads in a doubled up
ply and say they have a high tpi rating. But the tire
rides like a garden hose anyway.

The reason that wider tires need stronger thicker side
walls is that the required tensile strength increases
as the curvature decreases. The operative term is
`hoop stress.'

>
> The ContinentalUltraGatorSkin 700x28, and Panaracer Pasela 700x28 also
> come to mind. At the least the Continental has a hight thread count -
> as always...
>
>
> > This difference
> >alone will negate the advantage in width of the 28 mm wide tire.
>
> Not sure what you mean here. I've learned that lower tpi equals more
> confort but less performance. Am I missing something?

I have 25 mm tires on one bike, 28 mm on the other.
There is no discernible difference to me.
Both are good quality slicks with as supple a casing
as possible, but the 28 mm has a thicker casing
that eats up the advantage of the slightly lower
tire pressure.

Thinner side walls, casing, and tread equal more comfort
other things being equal. An honest 127 tpi tire will
deliver comfort and easier rolling because it will deliver
a thinner casing.

> Aramid vs steel bead: besides a slight weigh diference, what
> perceivable diferences do they have?

None that I know of. Aramid bead tires fold nicely
for carrying, but few people really need to carry
a spare tire. Some say the aramid bead will stretch
a bit to make mounting and unmounting easier.
Steel beads do not stretch, and if the tire is a
bear to mount it will remain so.

> >I find 25 mm wide tires to be comfortable.
> >If you want wide tires for comfort, then you need a new frame.
>
> No, I don't think I want a full suspension frame ;-)

I mean a frame with more space for tires.
You're having me on, aren't you?

Try the Avocet Fasgrip. Definitely go for slick tread.

--
Michael Press

Jose

On Wed, 18 Jun 2008 07:01:05 -0700 (PDT), Art Harris
<n2ah@hotmail.com> wrote:


Hi Art,

>Continental counts the threads in each ply. It's not a fair
>comparison.

Yes, I know, but for several of their tyres they say how many plies
the tyre has, so diving the huge tpi count for the number of plies
gives a rough idea of a real tpi count


>A high tpi casing is more flexible and has lower rolling resistance.
>If anything, it may be more comfortable.

Well, no doubt about more TPIs = better performance. As to confort, I
have the opposite idea, from experience: my present Maxis Detonator
700x25, at 66 tpi, feels smoother than my previous Continental Ultra
GatorSkin rougly at about 80-90 tpi...

Besides, all opinions I've found about the Michelin Dynamic, say it's
a comfy tyre, albeit less performant than most - it has 33 tpi ;-P

Best,
Jose

Jose

On Wed, 18 Jun 2008 12:26:13 -0700, Michael Press <rubrum@pacbell.net>
wrote:

Hi Michael,


>> Vittoria Rubino Pro and Pro Tech, 700x28, 120 tpi, 70-115 psi, 230-250
>> gr.
>
>I am not saying that Vittoria does, but some companies
>fudge the advertised thread per inch.

I know Continental does that. Don't know about Vittoria too although I
get the feeling they don't.

Anyway, I can't seem to find the Rubino Pro or Pro Tech 700x28 for
sale in Europe...


>> > This difference
>> >alone will negate the advantage in width of the 28 mm wide tire.

In terms of performance it might. However, maybe I can ride the 28 mm
at a higher pressure, which I still think may give better performance,
and be less prone to pinch plating around town.


>> Not sure what you mean here. I've learned that lower tpi equals more
>> confort but less performance. Am I missing something?
>
>I have 25 mm tires on one bike, 28 mm on the other.
>There is no discernible difference to me.
>Both are good quality slicks with as supple a casing
>as possible, but the 28 mm has a thicker casing
>that eats up the advantage of the slightly lower
>tire pressure.

OK, now suppose you pump up the 28mm to the same pressure you do on
the 25mm... Continental seems to think that, all other things being
equal, a wider tyre will allow better performance.

Anyway, to cut a long story short:
a) if the the 28mm allows to ride around town at 80 psi instead of 70
with my present 25 mm, I think I'll be better off, performance and
safety wise;
b) Considering I normally don't pump up the tyres higher than 90 psi
on longish rides, I'll probably get better performance from a 28mm
tyre at that pressure, or I might even pump up the tyre to 100psi.


>> No, I don't think I want a full suspension frame ;-)
>
>I mean a frame with more space for tires.
>You're having me on, aren't you?

I was pulling your leg, yes ;-)


>Try the Avocet Fasgrip. Definitely go for slick tread.

That's a tyre brand I've never been able to find in Europe... Go
figure.

Best,
Jose

Michael Press

In article <485f3846.6904500@news20.forteinc.com>,
go.spam@somewhere.else (Jose) wrote:
[...]
> Anyway, to cut a long story short:
> a) if the the 28mm allows to ride around town at 80 psi instead of 70
> with my present 25 mm, I think I'll be better off, performance and
> safety wise;
> b) Considering I normally don't pump up the tyres higher than 90 psi
> on longish rides, I'll probably get better performance from a 28mm
> tyre at that pressure, or I might even pump up the tyre to 100psi.

Performance is in cornering.
I prefer the smaller thinner tires for that.
I pump tires to ~8 bar, then run them until they are
down to 5.5 bar. I notice the difference in pressure
but not a difference in comfort. In one way the lower
pressure is less `comfortable' because cornering gets
less positive.

--
Michael Press

jobst.brandt@stanfordalumni.org

Michael Press wrote:

>> Anyway, to cut a long story short:

>> a) if the the 28mm allows to ride around town at 80 psi instead of
>> 70 with my present 25 mm, I think I'll be better off,
>> performance and safety wise;

>> b) Considering I normally don't pump up the tyres higher than 90
>> psi on longish rides, I'll probably get better performance from
>> a 28mm tyre at that pressure, or I might even pump up the tyre
>> to 100psi.

> Performance is in cornering. I prefer the smaller thinner tires for
> that.

Although I have no data on it, I believe fatter tires corner better,
mainly because they can be run softer to absorb paving irregularities
while not allowing perceptible lateral flex. Beside that, they give
larger road contact that, I believe, must improve traction. We can
take some hints from motorcycles in this respect.

> I pump tires to ~8 bar, then run them until they are down to 5.5
> bar. I notice the difference in pressure but not a difference in
> comfort. In one way the lower pressure is less `comfortable' because
> cornering gets less positive.

I prefer 28mm cross section tires between 6 and 7 bar (aka 85-100 psi)
to achieve a sure cornering response on typical mountain road descents.

Jobst Brandt

Tom Kunich

<jobst.brandt@stanfordalumni.org> wrote in message
news:485fbeef$0$17203$742ec2ed@news.sonic.net...
>
> I prefer 28mm cross section tires between 6 and 7 bar (aka 85-100 psi)
> to achieve a sure cornering response on typical mountain road descents.

What tires do you normally use? I used to use those Avocet 25's which used
to be 28mm but they've changed a great deal now so I'm not sure what to buy.
The last Avocet 28mm tires I bought lasted only half as long as the
preceding one's of the old style.

Art Harris

Tom Kunich wrote:
> > I prefer 28mm cross section tires between 6 and 7 bar (aka 85-100 psi)
> > to achieve a sure cornering response on typical mountain road descents.
>
> What tires do you normally use? I used to use those Avocet 25's which used
> to be 28mm
>

Other way around. The old Avocets labeled 700 x 28 measured 25 mm on a
rim. Those were the ones with the tan sidewalls (made in Japan by
IRC).

> but they've changed a great deal now so I'm not sure what to buy.
> The last Avocet 28mm tires I bought lasted only half as long as the
> preceding one's of the old style.
>

More recent Avocets (black sidewalls) ran true to size, but were made
in Korea, and reportedly had problems.

Art Harris

jobst.brandt@stanfordalumni.org

Tom Kunich wrote:

>> I prefer 28mm cross section tires between 6 and 7 bar (aka 85-100
>> psi) to achieve a sure cornering response on typical mountain road
>> descents.

> What tires do you normally use? I used to use those Avocet 25's
> which used to be 28mm but they've changed a great deal now so I'm
> not sure what to buy. The last Avocet 28mm tires I bought lasted
> only half as long as the preceding one's of the old style.

I thin the Avocets are not what they were since IRC got out of the
bicycle tire business. I think I told the story of those tires when
they first came out. IRC had a new rubber compound that was all
things to all riders in that it had a slower wear rate but did not
give up any other good characteristics.

The wear rate was apparent to users but an engineer named Schallamach
discovered that in normal use, the wear rate of tire tread is
proportional to the wave length of surface roughness, it being a
skid-melt nature that kicks up tiny waves of molten rubber. These are
waves are visible after a skid, but much less so for normal riding.

The wavelength appears as a lighter colored matte texture, hardly
noticeable because it is uniform along the tread. The IRC rubber was
visibly darker from its finer surface roughness. However this rubber
didn't adhere well to tire casings so a primer of old style tread
rubber was used before applying the new compound, and that solved the
adhesion problem. When lighter colored rubber appeared it was shortly
before the cords showed and that took a long time.

When production transferred to Taiwan, that feature was lost and we
are back to faster wearing rubber.

I ride various Continentals now and get the impression that they also
use a longer waring tread compound from the tire life I am seeing. I
suppose someone at a bicycle magazine could perform some microscope
measurements of Schallamach waves of various tires and report on
it... if they weren't afraid of losing advertisers.

Jobst Brandt

Tom Kunich

<jobst.brandt@stanfordalumni.org> wrote in message
news:485fda95$0$17206$742ec2ed@news.sonic.net...
>
> I ride various Continentals now and get the impression that they also
> use a longer waring tread compound from the tire life I am seeing. I
> suppose someone at a bicycle magazine could perform some microscope
> measurements of Schallamach waves of various tires and report on
> it.

I used to ride the old Continental Gran Prixs. They had a nice long wearing
rubber (rumored to be real rubber). The problem with them was that they
didn't have a cover over the sidewalls and some 6 (!!!) tires in a row
suffered from flats due to sidewall cuts. I moved away from Continentals
after that though since I have tried various other Continentals which don't
seem to me to wear anywhere nearly as long as those Gran Prixs.

Because of one of those destroyed Gran Prixs I bought an Avocet one morning.
I would normally get about 2,500 miles on a Gran Prix if I rotated them. I
left that 28mm Avocet on the back for almost 4,000 miles so obviously I'd
like to get something else like that.

So far the only tires I've used that got better than that are the latest
Vredesteins.