Speedo Correction For Different-Sized Tires?

"(Pete Cresswell)" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

The diff is 125. 125/2090 = approx 6%.

Can I just use this as a straight-line correction factor for both milage
and speed?

Yes. The speedometer is just counting revolutions.

On Tue, 12 Oct 2004 23:19:49 GMT, "(Pete Cresswell)" <[email hidden]>

Quoted message said:

My speedo is set for fat tires: 2090 mm for one complete rotation.

Today I did a ride that the speedo said was 46 miles - but on slicks that
measure only 1965 mm for one complete rotation.

The diff is 125. 125/2090 = approx 6%.

Can I just use this as a straight-line correction factor for both milage and
speed?

e.g. Today's nominal 46 miles actually = 46 * .94 = 43.2?

or 20 mph nominal actually = 20 * .94 = 18.8 mph?

Obviously not a religious issue - but might be useful when comparing pedaling
effort between tires, or navigating to precise directions.

Dear Pete,

If you can live with such vague approximations of such
crucial figures (and do them in your head in time to avoid
almost certain death), then your shameful scheme should
work.

After all, it's pretty much what the speedometer does
anyway. Every time the magnet whips by the sensor, the
computer yawns and checks to see how many miles or
kilometers per hour that many clicks in that many seconds
should be. It trusts you to tell the truth.

In 1968, I spent a fearfully noisy and uncomfortable few
hours as a little boy in the cramped jump seat of a doctor's
poorly muffled Aston Martin, bored witless and watching the
speedometer needle sitting on the 100 mph mark as we headed
dead east out US 50 to the Kansas border.

Pawing through the glove box at one stop, I found (of all
things) a copy of the doctor's will and was intrigued to see
that it covered what to do if he died first, if his wife
died first, or if no one could tell who died first.

His wife wasn't with us, so I lost interest and kept
looking.

Even more intriguing was a handwritten table of corrections
from some garage that had been paid to calibrate the Aston
Martin's speedometer. I felt much better knowing that
although the doctor kept the needle right on 100 mph, we
were doing only 94 mph.

Hope you feel better at 18.8 mph.

Carl Fogel

[email hidden] wrote in message news:<[email hidden]>...

Quoted message said:

On Tue, 12 Oct 2004 23:19:49 GMT, "(Pete Cresswell)" <[email hidden]>

Quoted message said:

My speedo is set for fat tires: 2090 mm for one complete rotation.

Today I did a ride that the speedo said was 46 miles - but on slicks that
measure only 1965 mm for one complete rotation.

The diff is 125. 125/2090 = approx 6%.

Can I just use this as a straight-line correction factor for both milage and
speed?

e.g. Today's nominal 46 miles actually = 46 * .94 = 43.2?

or 20 mph nominal actually = 20 * .94 = 18.8 mph?

Obviously not a religious issue - but might be useful when comparing pedaling
effort between tires, or navigating to precise directions.

Dear Pete,

If you can live with such vague approximations of such
crucial figures (and do them in your head in time to avoid
almost certain death), then your shameful scheme should
work.

After all, it's pretty much what the speedometer does
anyway. Every time the magnet whips by the sensor, the
computer yawns and checks to see how many miles or
kilometers per hour that many clicks in that many seconds
should be. It trusts you to tell the truth.

In 1968, I spent a fearfully noisy and uncomfortable few
hours as a little boy in the cramped jump seat of a doctor's
poorly muffled Aston Martin, bored witless and watching the
speedometer needle sitting on the 100 mph mark as we headed
dead east out US 50 to the Kansas border.

Pawing through the glove box at one stop, I found (of all
things) a copy of the doctor's will and was intrigued to see
that it covered what to do if he died first, if his wife
died first, or if no one could tell who died first.

His wife wasn't with us, so I lost interest and kept
looking.

Even more intriguing was a handwritten table of corrections
from some garage that had been paid to calibrate the Aston
Martin's speedometer. I felt much better knowing that
although the doctor kept the needle right on 100 mph, we
were doing only 94 mph.

Hope you feel better at 18.8 mph.

Carl Fogel

*********************************************

Hi, Carl, I love your story.

You're WAY ahead of your time. :-)

Lewis.

*************************

RE/

Quoted message said:

Dear Pete,

Another good laugh from Carl...Thanks!...
--
PeteCresswell

Quoted message said:

Even more intriguing was a handwritten table of corrections
from some garage that had been paid to calibrate the Aston
Martin's speedometer. I felt much better knowing that
although the doctor kept the needle right on 100 mph, we
were doing only 94 mph.

Might've been cheaper, too, had he gotten a ticket, so it's a double-whammy.

--
Phil, Squid-in-Training

Squid-in-Training said:

Quoted message said:

Even more intriguing was a handwritten table of corrections
from some garage that had been paid to calibrate the Aston
Martin's speedometer. I felt much better knowing that
although the doctor kept the needle right on 100 mph, we
were doing only 94 mph.

Might've been cheaper, too, had he gotten a ticket, so it's a double-whammy.

Dear Phil,

In 1968, the likelihood of being stopped for speeding on US
50 heading east on the Great Plains toward Kansas along the
Arkansas River was about the same as being attacked by
Comanches.

At a rough guess, there might have been a population of
three thousand people in a hundred and twenty miles, many of
whom did not yet have party lines or indoor plumbing.

To give you some idea of how flat and empty the area is, my
father later shot by sheer luck what everyone agreed was an
antelope whose horns would have been a Colorado record.
Unfortunately for the glory of the Fogel clan, it was
eventually determined that the beast had probably met its
fate about a mile into Kansas.

Even today, there isn't much out there, and even less when
you get away from the highway and the river--dryland farming
doesn't pay out there. Nor do speed traps.

The U.S. Department of Transportation High-Speed Test track
is out there, a hundred-mile train-loop where the crews go
in circles for a thousand miles a night, squashing
rattlesnakes on the tracks in the summer.

Carl Fogel

[email hidden] said...

Quoted message said:

Even today, there isn't much out there, and even less when
you get away from the highway and the river--dryland farming
doesn't pay out there. Nor do speed traps.

I found out my little SUV is governed at 100 mph while in Wyoming
recently. I was barely moving faster than the 18 wheelers going
downhill.

RE/

Quoted message said:

I found out my little SUV is governed at 100 mph while in Wyoming
recently. I was barely moving faster than the 18 wheelers going
downhill.

Something that you've probably already considered, but was new to me: the
maximum speed rating of tires. Doesn't seem TB promenantly displayed/widely
known in the USA, but it's prominent in Europe. Last I heard most US tires
were rated for 85 mph.
--
PeteCresswell

SuperSlinky <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

[email hidden] said...

Quoted message said:

Even today, there isn't much out there, and even less when
you get away from the highway and the river--dryland farming
doesn't pay out there. Nor do speed traps.

Quoted message said:

I found out my little SUV is governed at 100 mph while in Wyoming
recently. I was barely moving faster than the 18 wheelers going
downhill.

I can understand cars and trucks being governed so they can't go
rediculous speeds but 100 mph is a bit low. On 2-way highways in
remote areas even fairly conservative drivers top 100 while
passing someone. On a 2-way highway it is certainly safer to pass
a slower driver quickly than to hit your limiter and sit in the
left lane longer.

My first two cars wouldn't even go 100. My first was a Toyota
Starlett that could only go 80 on a downgrade or with a slight
tailwind; my second was a Volvo 240 that could just manage 85.
While driving through remote areas of Texas and Oklahoma I was
often the slowest car on the road even with the accelerator floored.
--
Bruce Jackson

[email hidden] wrote in message news:<[email hidden]>...

Quoted message said:

Squid-in-Training said:

Quoted message said:

Even more intriguing was a handwritten table of corrections
from some garage that had been paid to calibrate the Aston
Martin's speedometer. I felt much better knowing that
although the doctor kept the needle right on 100 mph, we
were doing only 94 mph.

Might've been cheaper, too, had he gotten a ticket, so it's a double-whammy.

Dear Phil,

In 1968, the likelihood of being stopped for speeding on US
50 heading east on the Great Plains toward Kansas along the
Arkansas River was about the same as being attacked by
Comanches.

At a rough guess, there might have been a population of
three thousand people in a hundred and twenty miles, many of
whom did not yet have party lines or indoor plumbing.

To give you some idea of how flat and empty the area is, my
father later shot by sheer luck what everyone agreed was an
antelope whose horns would have been a Colorado record.
Unfortunately for the glory of the Fogel clan, it was
eventually determined that the beast had probably met its
fate about a mile into Kansas.

Even today, there isn't much out there, and even less when
you get away from the highway and the river--dryland farming
doesn't pay out there. Nor do speed traps.

The U.S. Department of Transportation High-Speed Test track
is out there, a hundred-mile train-loop where the crews go
in circles for a thousand miles a night, squashing
rattlesnakes on the tracks in the summer.

Carl Fogel

For unrelated reasons, I was just ogling a local map
and saw to my shame that the DOT railroad test track
is not the hundred-mile loop of which I boasted--it's
only a dinky little ten-mile oval, even though there's
plenty of room for a hundred-mile oval in the empty
quarter between Ordway and Punkin Center.

I'd like to think that I was misled by long-ago
conversations with railroad employees, but the most
likely culprit is my fevered imagination.

Carl Fogel

"Carl Fogel" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

[email hidden] wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

Squid-in-Training said:

> Even more intriguing was a handwritten table of corrections
> from some garage that had been paid to calibrate the Aston
> Martin's speedometer. I felt much better knowing that
> although the doctor kept the needle right on 100 mph, we
> were doing only 94 mph.

Might've been cheaper, too, had he gotten a ticket, so it's a

double-whammy.

Quoted message said:

Quoted message said:

Dear Phil,

In 1968, the likelihood of being stopped for speeding on US
50 heading east on the Great Plains toward Kansas along the
Arkansas River was about the same as being attacked by
Comanches.

At a rough guess, there might have been a population of
three thousand people in a hundred and twenty miles, many of
whom did not yet have party lines or indoor plumbing.

To give you some idea of how flat and empty the area is, my
father later shot by sheer luck what everyone agreed was an
antelope whose horns would have been a Colorado record.
Unfortunately for the glory of the Fogel clan, it was
eventually determined that the beast had probably met its
fate about a mile into Kansas.

Even today, there isn't much out there, and even less when
you get away from the highway and the river--dryland farming
doesn't pay out there. Nor do speed traps.

The U.S. Department of Transportation High-Speed Test track
is out there, a hundred-mile train-loop where the crews go
in circles for a thousand miles a night, squashing
rattlesnakes on the tracks in the summer.

Carl Fogel

For unrelated reasons, I was just ogling a local map
and saw to my shame that the DOT railroad test track
is not the hundred-mile loop of which I boasted--it's
only a dinky little ten-mile oval, even though there's
plenty of room for a hundred-mile oval in the empty
quarter between Ordway and Punkin Center.

I'd like to think that I was misled by long-ago
conversations with railroad employees, but the most
likely culprit is my fevered imagination.

Carl Fogel

Ahhh...what's an order of magnitude among friends?...you probably would
wonder why you weren't tired after riding that "century" in about 40
minutes...