Potential good news for Mt. Washington access. - Page 13

01-10-2005, 04:56 AM

Benjamin Lewis <[Only registered and activated users can see links. ].ca> wrote:

>jobst brandt wrote:

>> I think we are scraping at nits. Besides, who gives a damn how much
>> pressure a stationary wheel can hold. We are interested in safely
>> riding down steep grades.
>
>Then shouldn't it help to know as much as possible about what factors
>affect blowoff? In addition to the static case, you could ride the bike
>with increasingly higher pressures, without braking, to test your
>hypothesis that motion between the tire and rim is contributory. If
>temperature as well as pressure were a factor, perhaps using a different
>material for the tire bead would help.

I think Jobst nailed it on the head. While it might be interesting to
explore all the nuances of this phenomenon, all that really matters is
what the tire does when actually rolling down a steep hill with a
rider on board.

But to add my voice to the chorus of armchair testers, I'd suggest
that it might be interesting to see the effects of using a deep rim on
the rear wheel to see how effective the extra mass is at getting rid
of the heat.

Mark Hickey
Habanero Cycles
[Only registered and activated users can see links. ]
Home of the $695 ti frame

01-10-2005, 09:01 AM

Benjamin Lewis writes:

>>> There still needs to be a control for temperature in the static
>>> test, since of course compressing air into the tire raises the
>>> temperature of the air and casing. However, if the tire is
>>> inflated slowly, actual temperature rise will be insignificant.

>>> In addition to the motion between the tire and rim that Jobst
>>> Brandt mentions as possibly affecting blow-off pressure, there is
>>> the effect of heating the tire, since the rubber will change
>>> properties with temperature.

>> I don't believe inflating a tire makes enough temperature
>> difference to worry about. I have not noticed hot tires from
>> inflation nor even a hot hose or brass hose-to-valve coupler (hose
>> chuck). I am aware of Silca frame fit pump heads getting hot in
>> the hand while pumping but that is a big difference from a floor
>> pump and hose.

>> I think we are scraping at nits. Besides, who gives a damn how
>> much pressure a stationary wheel can hold. We are interested in
>> safely riding down steep grades.

> Then shouldn't it help to know as much as possible about what
> factors affect blowoff? In addition to the static case, you could
> ride the bike with increasingly higher pressures, without braking,
> to test your hypothesis that motion between the tire and rim is
> contributory. If temperature as well as pressure were a factor,
> perhaps using a different material for the tire bead would help.

OK. Do it. I'm interested in brake heating and the resulting hazard
of crashing... fatally. You can perform the tests you propose without
instrumentation so what's keeping you from doing so? You could "know
as much as possible about what factors affect blowoff."

Jobst Brandt
[Only registered and activated users can see links. ]

01-10-2005, 09:01 AM

Benjamin Lewis writes:

>>> There still needs to be a control for temperature in the static
>>> test, since of course compressing air into the tire raises the
>>> temperature of the air and casing. However, if the tire is
>>> inflated slowly, actual temperature rise will be insignificant.

>>> In addition to the motion between the tire and rim that Jobst
>>> Brandt mentions as possibly affecting blow-off pressure, there is
>>> the effect of heating the tire, since the rubber will change
>>> properties with temperature.

>> I don't believe inflating a tire makes enough temperature
>> difference to worry about. I have not noticed hot tires from
>> inflation nor even a hot hose or brass hose-to-valve coupler (hose
>> chuck). I am aware of Silca frame fit pump heads getting hot in
>> the hand while pumping but that is a big difference from a floor
>> pump and hose.

>> I think we are scraping at nits. Besides, who gives a damn how
>> much pressure a stationary wheel can hold. We are interested in
>> safely riding down steep grades.

> Then shouldn't it help to know as much as possible about what
> factors affect blowoff? In addition to the static case, you could
> ride the bike with increasingly higher pressures, without braking,
> to test your hypothesis that motion between the tire and rim is
> contributory. If temperature as well as pressure were a factor,
> perhaps using a different material for the tire bead would help.

OK. Do it. I'm interested in brake heating and the resulting hazard
of crashing... fatally. You can perform the tests you propose without
instrumentation so what's keeping you from doing so? You could "know
as much as possible about what factors affect blowoff."

Jobst Brandt
[Only registered and activated users can see links. ]

01-10-2005, 09:01 AM

Benjamin Lewis writes:

>>> There still needs to be a control for temperature in the static
>>> test, since of course compressing air into the tire raises the
>>> temperature of the air and casing. However, if the tire is
>>> inflated slowly, actual temperature rise will be insignificant.

>>> In addition to the motion between the tire and rim that Jobst
>>> Brandt mentions as possibly affecting blow-off pressure, there is
>>> the effect of heating the tire, since the rubber will change
>>> properties with temperature.

>> I don't believe inflating a tire makes enough temperature
>> difference to worry about. I have not noticed hot tires from
>> inflation nor even a hot hose or brass hose-to-valve coupler (hose
>> chuck). I am aware of Silca frame fit pump heads getting hot in
>> the hand while pumping but that is a big difference from a floor
>> pump and hose.

>> I think we are scraping at nits. Besides, who gives a damn how
>> much pressure a stationary wheel can hold. We are interested in
>> safely riding down steep grades.

> Then shouldn't it help to know as much as possible about what
> factors affect blowoff? In addition to the static case, you could
> ride the bike with increasingly higher pressures, without braking,
> to test your hypothesis that motion between the tire and rim is
> contributory. If temperature as well as pressure were a factor,
> perhaps using a different material for the tire bead would help.

OK. Do it. I'm interested in brake heating and the resulting hazard
of crashing... fatally. You can perform the tests you propose without
instrumentation so what's keeping you from doing so? You could "know
as much as possible about what factors affect blowoff."

Jobst Brandt
[Only registered and activated users can see links. ]

01-10-2005, 09:01 AM

Benjamin Lewis writes:

>>> There still needs to be a control for temperature in the static
>>> test, since of course compressing air into the tire raises the
>>> temperature of the air and casing. However, if the tire is
>>> inflated slowly, actual temperature rise will be insignificant.

>>> In addition to the motion between the tire and rim that Jobst
>>> Brandt mentions as possibly affecting blow-off pressure, there is
>>> the effect of heating the tire, since the rubber will change
>>> properties with temperature.

>> I don't believe inflating a tire makes enough temperature
>> difference to worry about. I have not noticed hot tires from
>> inflation nor even a hot hose or brass hose-to-valve coupler (hose
>> chuck). I am aware of Silca frame fit pump heads getting hot in
>> the hand while pumping but that is a big difference from a floor
>> pump and hose.

>> I think we are scraping at nits. Besides, who gives a damn how
>> much pressure a stationary wheel can hold. We are interested in
>> safely riding down steep grades.

> Then shouldn't it help to know as much as possible about what
> factors affect blowoff? In addition to the static case, you could
> ride the bike with increasingly higher pressures, without braking,
> to test your hypothesis that motion between the tire and rim is
> contributory. If temperature as well as pressure were a factor,
> perhaps using a different material for the tire bead would help.

OK. Do it. I'm interested in brake heating and the resulting hazard
of crashing... fatally. You can perform the tests you propose without
instrumentation so what's keeping you from doing so? You could "know
as much as possible about what factors affect blowoff."

Jobst Brandt
[Only registered and activated users can see links. ]

01-10-2005, 09:02 AM

Alfred Ryder wrote:

>
> I would be interested in knowing whether the blow-off point is affected by
> whether someone is sitting on the bike or not. The only blow-off I have had
> was a few seconds after coming to a complete stop.

When our tandem was brand new (long, long ago) it suffered two blowouts
as it sat alone in a bedroom, at least an hour after mounting and
inflating the tires. I never did figure that out.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

01-10-2005, 09:02 AM

Alfred Ryder wrote:

>
> I would be interested in knowing whether the blow-off point is affected by
> whether someone is sitting on the bike or not. The only blow-off I have had
> was a few seconds after coming to a complete stop.

When our tandem was brand new (long, long ago) it suffered two blowouts
as it sat alone in a bedroom, at least an hour after mounting and
inflating the tires. I never did figure that out.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

01-10-2005, 09:02 AM

Alfred Ryder wrote:

>
> I would be interested in knowing whether the blow-off point is affected by
> whether someone is sitting on the bike or not. The only blow-off I have had
> was a few seconds after coming to a complete stop.

When our tandem was brand new (long, long ago) it suffered two blowouts
as it sat alone in a bedroom, at least an hour after mounting and
inflating the tires. I never did figure that out.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

01-10-2005, 09:02 AM

Alfred Ryder wrote:

>
> I would be interested in knowing whether the blow-off point is affected by
> whether someone is sitting on the bike or not. The only blow-off I have had
> was a few seconds after coming to a complete stop.

When our tandem was brand new (long, long ago) it suffered two blowouts
as it sat alone in a bedroom, at least an hour after mounting and
inflating the tires. I never did figure that out.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

01-10-2005, 09:32 AM

Jobst Brandt wrote:

> ...We are interested in safely riding down steep grades.

And one should add, "without increasing weight, expense, and mechanical
complexity."

It would be a simple matter to use a tandem (e.g. Arai) drag brake on a
single bicycle and/or use adequately sized disc brakes.

--
Tom Sherman - Near Rock Island