rec.bicycles.tech - FAQ?

[[email protected]]

On 7 Mar 2007 05:01:07 GMT, Mike DeMicco
<[email protected]> wrote:

>[email protected] wrote in news:45eadcba$0$14085
>[email protected]:
>
>> Don't fool yourself, technology in bicycling does not move but with
>> glacial speed. You haven't missed a thing.
>>
>
>Well, I thought index shifting was a big improvement over crappy friction
>shifting. How about clipless pedals? The mountain bike? Mountain bike
>suspension? Bicycle computers? Lighting systems? I guess by your
>definition, you can say the same thing about automobiles.

Dear Mike,

Your other examples may well be true, but numerous clipless pedals
(with float) were patented before 1900:

http://www.speedplay.com/index.cfm?fuseaction=home.history

They fell out of favor for over 80 years, probably because they just
aren't terribly useful for ordinary riding, as endless children and
commuters testify every day.

Cheers,

Carl Fogel

 

[[email protected]]

Mike DeMicco writes:

>> Don't fool yourself, technology in bicycling does not move but with
>> glacial speed. You haven't missed a thing.

> Well, I thought index shifting was a big improvement over crappy
> friction shifting. How about clipless pedals? The mountain bike?
> Mountain bike suspension? Bicycle computers? Lighting systems? I
> guess by your definition, you can say the same thing about
> automobiles.

So how fast did that overtake you. As I recall it took years to
decide what the problem was in shifting, the impetus coming from
affluent riders who could not pedal and reach down to shift at the
same time. As you see, pedals have still not decided how to do it.
Jo Breeze produced the first mountain bike many years ago:

http://www.sheldonbrown.com/brandt/mtb-history.html

Not so. If you consider that there is no lube rack at your local gas
station, there are no push rods and rocker arms, nor hydraulic valve
lifters and no one messes with the valves. These are invisible
advances that were substantial, cars that don't reach 200,000 miles
service being considered duds today. It's not only the valve gear.
The whole engine is well understood today as is suspension that on
todays cars is better than sports cars of 20 years ago. A sports car
today is a fancy two seater on a normal car basis. Just poke at a new
car anywhere you like and you have substantial technical advances.

Until competition from Japan raised the standard, we suffered under
cars designed by mechanics who didn't understand the technology. A
classic example is engine cooling.

http://en.wikipedia.org/wiki/Engine_cooling#Why_automobile_engines_were_air-cooled

We have a ghost town, Altamont, that existed primarily to service
boiling engines on Altamont pass. A side effect was that two
railroads (WP and SP) used helper steam engines to push trains over
the hill there and their crews drank a lot of beer.

http://tinyurl.com/222rym

You'll notice there is no town on the map anymore. If you were to
ask, I doubt that anyone there would realize that the town's existence
was for lack of a working water pump seal. I recall all the garages
there and on the summit of local HWY17 in the Santa Cruz Mountains at
Patchen Pass (1810' elev).

http://tinyurl.com/2543vb

Jobst Brandt

 

[Ben C]

On 2007-03-07, [email protected] <[email protected]> wrote:
> Mike DeMicco writes:
>
>>> Don't fool yourself, technology in bicycling does not move but with
>>> glacial speed. You haven't missed a thing.
>
>> Well, I thought index shifting was a big improvement over crappy
>> friction shifting. How about clipless pedals? The mountain bike?
>> Mountain bike suspension? Bicycle computers? Lighting systems? I
>> guess by your definition, you can say the same thing about
>> automobiles.
>
> So how fast did that overtake you. As I recall it took years to
> decide what the problem was in shifting, the impetus coming from
> affluent riders who could not pedal and reach down to shift at the
> same time. As you see, pedals have still not decided how to do it.
> Jo Breeze produced the first mountain bike many years ago:
>
> http://www.sheldonbrown.com/brandt/mtb-history.html
>
> Not so. If you consider that there is no lube rack at your local gas
> station, there are no push rods and rocker arms, nor hydraulic valve
> lifters and no one messes with the valves. These are invisible
> advances that were substantial, cars that don't reach 200,000 miles
> service being considered duds today. It's not only the valve gear.
> The whole engine is well understood today as is suspension that on
> todays cars is better than sports cars of 20 years ago. A sports car
> today is a fancy two seater on a normal car basis. Just poke at a new
> car anywhere you like and you have substantial technical advances.

Definitely agree with you there. I wonder how many of these advances
have come about as a result of computers-- both in the car, replacing
what used to be mechanical control systems, and as part of the design
process (modelling the valves, suspension, etc.).

But what about bikes? Much less has changed. We are even still expected
to do things like repacking bearings. I don't need my steenkin' grease
gun for the car any more.

 

[[email protected]]

On Mar 6, 11:53 pm, jim beam <[email protected]> wrote:
> [email protected] wrote:
> > On Mar 6, 1:08 am, jim beam <[email protected]> wrote:
> >> G.T. wrote:
> >>> So can we mount disc brake calipers on the front of the fork or not?
> >>> Greg
> >> if you want to to design to the material, not.
>
> > jim, it looks like Greg wasn't asking about your personal, nebulous,
> > artificial design standards! He was asking if it can be done.
>
> > Let's make it more general: Can cast aluminum parts be designed to
> > withstand tensile fatigue? You know - the way they routinely
> > are? ;-)
>
> > - Frank Krygowski
>
> you can have a bike made of corn muffins if you really want to, but i
> wouldn't ride it.

That's not a bad policy - at least, using current corn muffin
technology. ;-) But it's not what we were discussing. Most of us
can spot differences between corn muffins and aluminum alloys.

> i don't like riding tension fatigued castings either.

Again jim, we're not asking about your own personal, nebulous,
artificial design standards i.e. what you "like." We're asking about
manufacturing processes, engineering materials, and proper design as
used successfully on millions of good-quality bicycles.

Most bicyclists have no objection to using cast aluminum parts to
fight tensile fatigue, because their bikes successfully use many such
parts.

- Frank Krygowski

 

[[email protected]]

Tim McNamara wrote in part:

> ... When Jobst's
> position has been actually disproven by data or better explanations,
> he's accepted it and moved on.


Well, I notice that bit about "patch curing" is still
in the faq.

"Assuming a patch was properly installed, it may still
leak after a few miles, if used immediately after patching.
.... For reliable patches, the freshly patched tube should be put in
reserve, while a reserve tube is installed. This allows a new patch
more time to cure before being put into service."

Properly installed REMA patches can
be stuffed back into the tire and ridden
upon immediately after the patch is
installed without any problems whatsoever.
They do not leak and they do not need to
be 'cured.' Jobst's bullheadedness about
something as simple as this patch curing
nonsense does not give me confidence
as to the rest of the faq. It is a good read
though, overall. I say grab a few grains of
salt and dive in.

Robert

 

[[email protected]]

Robert r15757? writes:

>> ... When Jobst's position has been actually disproven by data or
>> better explanations, he's accepted it and moved on.

> Well, I notice that bit about "patch curing" is still in the FAQ.

> "Assuming a patch was properly installed, it may still leak after a
> few miles, if used immediately after patching. ... For reliable
> patches, the freshly patched tube should be put in reserve, while a
> reserve tube is installed. This allows a new patch more time to
> cure before being put into service."

> Properly installed REMA patches can be stuffed back into the tire
> and ridden upon immediately after the patch is installed without any
> problems whatsoever.

For evidence of patch mobility try pulling off a patch that has been
in place for several days in contrast to one that has just been made.
The REMA man at InterBike was of your opinion on this and patched a
tube as a demo. He was totally aghast when I puled it off easily.

Also, look at a tube you have ridden right after patching. You'll
notice that the patch(es) are bulbous and do not lie flat on the
deflated tube. That is because the tube expands when inflated and the
patch does not. If you are lucky the patch then sets on a smaller
area that it first covered and ends up as a bump.

> They do not leak and they do not need to be 'cured.' Jobst's
> bullheadedness about something as simple as this patch curing
> nonsense does not give me confidence as to the rest of the FAQ. It
> is a good read though, overall. I say grab a few grains of salt and
> dive in.

I never said that no such patch will remain sealed. You are injecting
your preconceived scenario into what I wrote. I suppose you also
missed the item about how to remove a patch that is well cured. Cured
patches cannot be pulled off a tube without heat.

Jobst Brandt

 

[[email protected]]

On 07 Mar 2007 18:07:23 GMT, [email protected] wrote:

>Robert r15757? writes:
>
>>> ... When Jobst's position has been actually disproven by data or
>>> better explanations, he's accepted it and moved on.
>
>> Well, I notice that bit about "patch curing" is still in the FAQ.
>
>> "Assuming a patch was properly installed, it may still leak after a
>> few miles, if used immediately after patching. ... For reliable
>> patches, the freshly patched tube should be put in reserve, while a
>> reserve tube is installed. This allows a new patch more time to
>> cure before being put into service."
>
>> Properly installed REMA patches can be stuffed back into the tire
>> and ridden upon immediately after the patch is installed without any
>> problems whatsoever.
>
>For evidence of patch mobility try pulling off a patch that has been
>in place for several days in contrast to one that has just been made.
>The REMA man at InterBike was of your opinion on this and patched a
>tube as a demo. He was totally aghast when I puled it off easily.
>
>Also, look at a tube you have ridden right after patching. You'll
>notice that the patch(es) are bulbous and do not lie flat on the
>deflated tube. That is because the tube expands when inflated and the
>patch does not. If you are lucky the patch then sets on a smaller
>area that it first covered and ends up as a bump.
>
>> They do not leak and they do not need to be 'cured.' Jobst's
>> bullheadedness about something as simple as this patch curing
>> nonsense does not give me confidence as to the rest of the FAQ. It
>> is a good read though, overall. I say grab a few grains of salt and
>> dive in.
>
>I never said that no such patch will remain sealed. You are injecting
>your preconceived scenario into what I wrote. I suppose you also
>missed the item about how to remove a patch that is well cured. Cured
>patches cannot be pulled off a tube without heat.
>
>Jobst Brandt

Dear Jobst,

Here's a picture of a Rema patch, cured for at least two months, which
I just peeled off in pieces with my thumbnail:

http://i17.tinypic.com/34hg8q1.jpg

Two pieces lie on the paper in front of the tube. A third piece is
peeled back and propped up with a toothpick.

I took the tube out of this box of patched tubes:

http://i18.tinypic.com/2ahw9ro.jpg

There may be some argument about whether the patches come off intact,
but they do peel off at room temperature. I expect that a freshly
glued patch does peel off more easily.

Cheers,

Carl Fogel

 

[A Muzi]

>>> G.T. wrote:
>>>> So can we mount disc brake calipers on the front of the fork or not?

jim beam wrote:
>>> if you want to to design to the material, not.

> [email protected] wrote:
>> jim, it looks like Greg wasn't asking about your personal, nebulous,
>> artificial design standards! He was asking if it can be done.
>> Let's make it more general: Can cast aluminum parts be designed to
>> withstand tensile fatigue? You know - the way they routinely
>> are? ;-)

jim beam wrote:
> you can have a bike made of corn muffins if you really want to, but i
> wouldn't ride it. i don't like riding tension fatigued castings either.
> idiot.

Oh, Jim, if it weren't Frank's comment you might have said, "Sure, a
modern melt-formed fork will have a larger disc mount on a front-mount
design than on a rear because the tabs will be in tension rather than
compression. Those larger disc mounts weigh something so top 'high
performance' models may still choose rear mount with a through axle"

There are reasonable differences of opinion on the _significance_ of
many factors involved but the pejorative 'idiot' was uncalled for, IMHO.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[[email protected]]

Carl Fogel writes:

>>>> ... When Jobst's position has been actually disproven by data or
>>>> better explanations, he's accepted it and moved on.

>>> Well, I notice that bit about "patch curing" is still in the FAQ.

>>> "Assuming a patch was properly installed, it may still leak after
>>> a few miles, if used immediately after patching. ... For reliable
>>> patches, the freshly patched tube should be put in reserve, while
>>> a reserve tube is installed. This allows a new patch more time to
>>> cure before being put into service."

>>> Properly installed REMA patches can be stuffed back into the tire
>>> and ridden upon immediately after the patch is installed without
>>> any problems whatsoever.

>> For evidence of patch mobility try pulling off a patch that has
>> been in place for several days in contrast to one that has just
>> been made. The REMA man at InterBike was of your opinion on this
>> and patched a tube as a demo. He was totally aghast when I puled
>> it off easily.

>> Also, look at a tube you have ridden right after patching. You'll
>> notice that the patch(es) are bulbous and do not lie flat on the
>> deflated tube. That is because the tube expands when inflated and
>> the patch does not. If you are lucky the patch then sets on a
>> smaller area that it first covered and ends up as a bump.

>>> They do not leak and they do not need to be 'cured.' Jobst's
>>> bullheadedness about something as simple as this patch curing
>>> nonsense does not give me confidence as to the rest of the FAQ. It
>>> is a good read though, overall. I say grab a few grains of salt
>>> and dive in.

>> I never said that no such patch will remain sealed. You are
>> injecting your preconceived scenario into what I wrote. I suppose
>> you also missed the item about how to remove a patch that is well
>> cured. Cured patches cannot be pulled off a tube without heat.

> Here's a picture of a Rema patch, cured for at least two months,
> which I just peeled off in pieces with my thumbnail:

http://i17.tinypic.com/34hg8q1.jpg

> Two pieces lie on the paper in front of the tube. A third piece is
> peeled back and propped up with a toothpick.

> I took the tube out of this box of patched tubes:

http://i18.tinypic.com/2ahw9ro.jpg

> There may be some argument about whether the patches come off
> intact, but they do peel off at room temperature. I expect that a
> freshly glued patch does peel off more easily.

I suspect you might not have prepared the patch area on the tube by
sanding off its skin that contains mold release. I don't guarantee
that an old patch cannot be removed, only that a fresh patch will
creep and may cause a leak. The patch removal procedure, of heating
the patch applies to well placed patches.

The indicators of a fresh patch being ridden upon installation is that
it bulges when the tube is deflated. The more damaging form is that
the middle of the patch lifts and when pulled off (or cut through with
shears) reveals that its underside is full of talcum from inside the
inner tube.

I notice that none of your tubes are airless and do not lie flat. If
you were to make them flat and kept that way by closing the valve, you
might notice that some of the patches bulge.

Jobst Brandt

 

[Ozark Bicycle]

On Mar 7, 12:57 pm, [email protected] wrote:
> On 07 Mar 2007 18:07:23 GMT, [email protected] wrote:
>
>
>
>
>
> >Robert r15757? writes:
>
> >>> ... When Jobst's position has been actually disproven by data or
> >>> better explanations, he's accepted it and moved on.
>
> >> Well, I notice that bit about "patch curing" is still in the FAQ.
>
> >> "Assuming a patch was properly installed, it may still leak after a
> >> few miles, if used immediately after patching. ... For reliable
> >> patches, the freshly patched tube should be put in reserve, while a
> >> reserve tube is installed. This allows a new patch more time to
> >> cure before being put into service."
>
> >> Properly installed REMA patches can be stuffed back into the tire
> >> and ridden upon immediately after the patch is installed without any
> >> problems whatsoever.
>
> >For evidence of patch mobility try pulling off a patch that has been
> >in place for several days in contrast to one that has just been made.
> >The REMA man at InterBike was of your opinion on this and patched a
> >tube as a demo. He was totally aghast when I puled it off easily.
>
> >Also, look at a tube you have ridden right after patching. You'll
> >notice that the patch(es) are bulbous and do not lie flat on the
> >deflated tube. That is because the tube expands when inflated and the
> >patch does not. If you are lucky the patch then sets on a smaller
> >area that it first covered and ends up as a bump.
>
> >> They do not leak and they do not need to be 'cured.' Jobst's
> >> bullheadedness about something as simple as this patch curing
> >> nonsense does not give me confidence as to the rest of the FAQ. It
> >> is a good read though, overall. I say grab a few grains of salt and
> >> dive in.
>
> >I never said that no such patch will remain sealed. You are injecting
> >your preconceived scenario into what I wrote. I suppose you also
> >missed the item about how to remove a patch that is well cured. Cured
> >patches cannot be pulled off a tube without heat.
>
> >Jobst Brandt
>
> Dear Jobst,
>
> Here's a picture of a Rema patch, cured for at least two months, which
> I just peeled off in pieces with my thumbnail:
>
> http://i17.tinypic.com/34hg8q1.jpg
>
> Two pieces lie on the paper in front of the tube. A third piece is
> peeled back and propped up with a toothpick.
>
> I took the tube out of this box of patched tubes:
>
> http://i18.tinypic.com/2ahw9ro.jpg
>
> There may be some argument about whether the patches come off intact,
> but they do peel off at room temperature. I expect that a freshly
> glued patch does peel off more easily.
>
>

Ah, but now you will be told by Mr. Brandt, in his usual condescending
tone, that you have applied the patch *incorrectly* and, hence, it was
easy to peel off. If you're lucky, you will be spared the gratuitous
snarl.

 

[[email protected]]

On 07 Mar 2007 20:06:54 GMT, [email protected] wrote:

>Carl Fogel writes:
>
>>>>> ... When Jobst's position has been actually disproven by data or
>>>>> better explanations, he's accepted it and moved on.
>
>>>> Well, I notice that bit about "patch curing" is still in the FAQ.
>
>>>> "Assuming a patch was properly installed, it may still leak after
>>>> a few miles, if used immediately after patching. ... For reliable
>>>> patches, the freshly patched tube should be put in reserve, while
>>>> a reserve tube is installed. This allows a new patch more time to
>>>> cure before being put into service."
>
>>>> Properly installed REMA patches can be stuffed back into the tire
>>>> and ridden upon immediately after the patch is installed without
>>>> any problems whatsoever.
>
>>> For evidence of patch mobility try pulling off a patch that has
>>> been in place for several days in contrast to one that has just
>>> been made. The REMA man at InterBike was of your opinion on this
>>> and patched a tube as a demo. He was totally aghast when I puled
>>> it off easily.
>
>>> Also, look at a tube you have ridden right after patching. You'll
>>> notice that the patch(es) are bulbous and do not lie flat on the
>>> deflated tube. That is because the tube expands when inflated and
>>> the patch does not. If you are lucky the patch then sets on a
>>> smaller area that it first covered and ends up as a bump.
>
>>>> They do not leak and they do not need to be 'cured.' Jobst's
>>>> bullheadedness about something as simple as this patch curing
>>>> nonsense does not give me confidence as to the rest of the FAQ. It
>>>> is a good read though, overall. I say grab a few grains of salt
>>>> and dive in.
>
>>> I never said that no such patch will remain sealed. You are
>>> injecting your preconceived scenario into what I wrote. I suppose
>>> you also missed the item about how to remove a patch that is well
>>> cured. Cured patches cannot be pulled off a tube without heat.
>
>> Here's a picture of a Rema patch, cured for at least two months,
>> which I just peeled off in pieces with my thumbnail:
>
> http://i17.tinypic.com/34hg8q1.jpg
>
>> Two pieces lie on the paper in front of the tube. A third piece is
>> peeled back and propped up with a toothpick.
>
>> I took the tube out of this box of patched tubes:
>
> http://i18.tinypic.com/2ahw9ro.jpg
>
>> There may be some argument about whether the patches come off
>> intact, but they do peel off at room temperature. I expect that a
>> freshly glued patch does peel off more easily.
>
>I suspect you might not have prepared the patch area on the tube by
>sanding off its skin that contains mold release.

[snip]

Dear Jobst,

You suspect wrong.

Cheers,

Carl Fogel

 

[Larry Dickman]

In article <[email protected]>,
[email protected] wrote:

> Not so. If you consider that there is no lube rack at your local gas
> station, there are no push rods and rocker arms, nor hydraulic valve
> lifters and no one messes with the valves. These are invisible
> advances that were substantial, cars that don't reach 200,000 miles
> service being considered duds today. It's not only the valve gear.
> The whole engine is well understood today as is suspension that on
> todays cars is better than sports cars of 20 years ago. A sports car
> today is a fancy two seater on a normal car basis. Just poke at a new
> car anywhere you like and you have substantial technical advances.

Added complexity doesn't make it better. Cars of the 60's were simple
and were easily and cheaply maintained by the backyard mechanic and got
you from point A to point B just as well. Today, forget about doing
anything yourself but minor maintenance. No push rods, rocker arms, or
hydraulic lifters in today's engines? Still in some to be sure. At least
there's no rubber band to break. You think mechanical valve lifters that
have to be adjusted every 35K miles like my '02 Honda Civic has is
better than hydraulic lifters? What's a lube rack? Just because they
took the zerk fitting out of ball and U joints didn't make them last
longer.

 

[[email protected]]

On Mar 7, 1:19 pm, Larry Dickman <[email protected]>
wrote:
> In article <[email protected]>,
>
> [email protected] wrote:
> > Not so. If you consider that there is no lube rack at your local gas
> > station, there are no push rods and rocker arms, nor hydraulic valve
> > lifters and no one messes with the valves. These are invisible
> > advances that were substantial, cars that don't reach 200,000 miles
> > service being considered duds today. It's not only the valve gear.
> > The whole engine is well understood today as is suspension that on
> > todays cars is better than sports cars of 20 years ago. A sports car
> > today is a fancy two seater on a normal car basis. Just poke at a new
> > car anywhere you like and you have substantial technical advances.
>
> Added complexity doesn't make it better. Cars of the 60's were simple
> and were easily and cheaply maintained by the backyard mechanic and got
> you from point A to point B just as well.

I don't agree with that... I remember seeing a VW Beetle ad when I was
a kid which said something about "...which is why so many of them live
to be 100,000". I don't think anyone would brag about that today.

 

[Ben C]

On 2007-03-07, Larry Dickman <[email protected]> wrote:
> In article <[email protected]>,
> [email protected] wrote:
>
>> Not so. If you consider that there is no lube rack at your local gas
>> station, there are no push rods and rocker arms, nor hydraulic valve
>> lifters and no one messes with the valves. These are invisible
>> advances that were substantial, cars that don't reach 200,000 miles
>> service being considered duds today. It's not only the valve gear.
>> The whole engine is well understood today as is suspension that on
>> todays cars is better than sports cars of 20 years ago. A sports car
>> today is a fancy two seater on a normal car basis. Just poke at a new
>> car anywhere you like and you have substantial technical advances.
>
> Added complexity doesn't make it better. Cars of the 60's were simple
> and were easily and cheaply maintained by the backyard mechanic and
> got you from point A to point B just as well.

In many cases they've improved things without adding complexity though.
20 years ago a lot of cars had the same basic MacPherson struts at the
front and dead axles located in various ways at the rear. Similar
picture today but it all just works much better (perhaps because of
computer modeling). With valvegear too, there's no big difference in
the complexity or number of moving parts, it just works much better.

Modern cars have a computer and a few sensors, but that replaces the
points, the centrifugal advance, the vacuum advance, and all manner of
little air pipes to and from the distributor and the carburetor.

> Today, forget about doing anything yourself but minor maintenance. No
> push rods, rocker arms, or hydraulic lifters in today's engines? Still
> in some to be sure. At least there's no rubber band to break. You
> think mechanical valve lifters that have to be adjusted every 35K
> miles like my '02 Honda Civic has is better than hydraulic lifters?

Do you really have to adjust the tappets in an '02 Civic? I am surprised
to hear that.

 

[Larry Dickman]

In article <[email protected]>,
[email protected] wrote:

> On Mar 7, 1:19 pm, Larry Dickman <[email protected]>
> wrote:
> > In article <[email protected]>,
> >
> > [email protected] wrote:
> > > Not so. If you consider that there is no lube rack at your local gas
> > > station, there are no push rods and rocker arms, nor hydraulic valve
> > > lifters and no one messes with the valves. These are invisible
> > > advances that were substantial, cars that don't reach 200,000 miles
> > > service being considered duds today. It's not only the valve gear.
> > > The whole engine is well understood today as is suspension that on
> > > todays cars is better than sports cars of 20 years ago. A sports car
> > > today is a fancy two seater on a normal car basis. Just poke at a new
> > > car anywhere you like and you have substantial technical advances.
> >
> > Added complexity doesn't make it better. Cars of the 60's were simple
> > and were easily and cheaply maintained by the backyard mechanic and got
> > you from point A to point B just as well.
>
> I don't agree with that... I remember seeing a VW Beetle ad when I was
> a kid which said something about "...which is why so many of them live
> to be 100,000". I don't think anyone would brag about that today.

So? You picked out an air cooled VW, not known as being a car that could
go much more than 100K miles without an engine rebuild. I knew someone
that had a '65 Chevy that got 200K, and that was with the motor oils of
the day in New York state, not sunny, warm, and dry California.

 

[Ed Pirrero]

On Mar 7, 1:19 pm, Larry Dickman <[email protected]>
wrote:
> In article <[email protected]>,
>
> [email protected] wrote:
> > Not so. If you consider that there is no lube rack at your local gas
> > station, there are no push rods and rocker arms, nor hydraulic valve
> > lifters and no one messes with the valves. These are invisible
> > advances that were substantial, cars that don't reach 200,000 miles
> > service being considered duds today. It's not only the valve gear.
> > The whole engine is well understood today as is suspension that on
> > todays cars is better than sports cars of 20 years ago. A sports car
> > today is a fancy two seater on a normal car basis. Just poke at a new
> > car anywhere you like and you have substantial technical advances.
>
> Added complexity doesn't make it better. Cars of the 60's were simple
> and were easily and cheaply maintained by the backyard mechanic and got
> you from point A to point B just as well.

Actually, not. Those cars needed more regular maintenance than modern
autos.

> Today, forget about doing
> anything yourself but minor maintenance.

Oh, please. Mid-to-late '90s Audis have a very faithful following
among the shadetree DIYers.

Up to and including 2000 $ 2001 MY cars, BTW. Folks do all kinds of
work on those cars without much more than metric hand tools and a good
multimeter.

> Just because they
> took the zerk fitting out of ball and U joints didn't make them last
> longer.

Your rose-colored glasses do not make fiction reality.

E.P.

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> Tim McNamara wrote in part:
>
> > ... When Jobst's position has been actually disproven by data or
> > better explanations, he's accepted it and moved on.
>
>
> Well, I notice that bit about "patch curing" is still in the faq.
>
> "Assuming a patch was properly installed, it may still leak after a
> few miles, if used immediately after patching. ... For reliable
> patches, the freshly patched tube should be put in reserve, while a
> reserve tube is installed. This allows a new patch more time to cure
> before being put into service."
>
> Properly installed REMA patches can be stuffed back into the tire and
> ridden upon immediately after the patch is installed without any
> problems whatsoever. They do not leak and they do not need to be
> 'cured.' Jobst's bullheadedness about something as simple as this
> patch curing nonsense does not give me confidence as to the rest of
> the faq. It is a good read though, overall. I say grab a few grains
> of salt and dive in.

Good advice. I read everything on Usenet and the Web with a helping of
salt.

That said, I've also had fresh Rema patches fail to stick and leak- and
that's with applying them correctly. IME it's not a problem with low
pressure tires (e.g. MTB tires) but it is a potential problem with 120
psi road tires. The air makes a little tunnel along the line of least
resistance. Something I have never though of until just now however, is
whether patch location makes a difference. If the patch is in full
contact with the rolling surfance of tire, would there be less
likelihood to lift and leak compared to a patch against the sidewall or
the rim?

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> On Mar 7, 1:19 pm, Larry Dickman <[email protected]>
> wrote:
> > In article <[email protected]>,
> >
> > [email protected] wrote:
> > > Not so. If you consider that there is no lube rack at your local
> > > gas station, there are no push rods and rocker arms, nor
> > > hydraulic valve lifters and no one messes with the valves. These
> > > are invisible advances that were substantial, cars that don't
> > > reach 200,000 miles service being considered duds today. It's
> > > not only the valve gear. The whole engine is well understood
> > > today as is suspension that on todays cars is better than sports
> > > cars of 20 years ago. A sports car today is a fancy two seater
> > > on a normal car basis. Just poke at a new car anywhere you like
> > > and you have substantial technical advances.
> >
> > Added complexity doesn't make it better. Cars of the 60's were
> > simple and were easily and cheaply maintained by the backyard
> > mechanic and got you from point A to point B just as well.
>
> I don't agree with that... I remember seeing a VW Beetle ad when I
> was a kid which said something about "...which is why so many of them
> live to be 100,000". I don't think anyone would brag about that
> today.

No, today 100,000 miles is on the low end of a reasonable service life.
My 16 year old Swedish brick has 171,000 miles and I see no reason not
to expect another 100,000 before it's done. By the time my 1988 Bronco
II had seen 100,000 miles it had needed to have the heads and
transmission replaced. I had damn near bought that vehicle twice by the
time I junked it. Whatta piece of ****. No wonder the US auto makers
are sucking pond water.

Cars nowadays- with certain exceptions like my former Ford- are better
built with closer tolerances than back in the 60s when shade tree
mechanics ruled the day. Solid state is more reliable than moving
parts. There's a lot less maintenance that needs to be done. But
modifications aren't as fun and simple as they were, as evidenced by the
"open source" EFI stuff out on the Internet that requires a computer to
set the fuel injection parameters and a soldering iron, circuit board
and silicon chips to build the hardware.

 

[jim beam]

[email protected] wrote:
<snip ****>
>
> Most bicyclists have no objection to using cast aluminum parts to
> fight tensile fatigue, because their bikes successfully use many such
> parts.

really? are they using the krygowski suppositional method of
determining which is which? have you done the metallography to back up
your claims? because last time i was at woolmort, there was a schwinn
varsity for sale at the princely sum of $200, and the crank had the word
"forged" raised on the inner face. if a $200 p.o.s. from woolmort uses
forged cranks, i seriously doubt there's any bike you've ever ridden
with a casting in such a critical position.

 

[jim beam]

A Muzi wrote:
>>>> G.T. wrote:
>>>>> So can we mount disc brake calipers on the front of the fork or not?
>
> jim beam wrote:
>>>> if you want to to design to the material, not.
>
>> [email protected] wrote:
>>> jim, it looks like Greg wasn't asking about your personal, nebulous,
>>> artificial design standards! He was asking if it can be done.
>>> Let's make it more general: Can cast aluminum parts be designed to
>>> withstand tensile fatigue? You know - the way they routinely
>>> are? ;-)
>
> jim beam wrote:
>> you can have a bike made of corn muffins if you really want to, but i
>> wouldn't ride it. i don't like riding tension fatigued castings
>> either. idiot.
>
> Oh, Jim, if it weren't Frank's comment you might have said, "Sure, a
> modern melt-formed fork will have a larger disc mount on a front-mount
> design than on a rear because the tabs will be in tension rather than
> compression. Those larger disc mounts weigh something so top 'high
> performance' models may still choose rear mount with a through axle"
>
> There are reasonable differences of opinion on the _significance_ of
> many factors involved but the pejorative 'idiot' was uncalled for, IMHO.

anyone that presumes to pose as an engineering professor, yet makes such
fundamental mistakes about fabrication process and mechanical properties
for "castings" as krygowski is indeed an idiot. no other word for it.