| Sysop: | Amessyroom |
|---|---|
| Location: | Fayetteville, NC |
| Users: | 27 |
| Nodes: | 6 (0 / 6) |
| Uptime: | 46:59:05 |
| Calls: | 632 |
| Calls today: | 3 |
| Files: | 1,187 |
| D/L today: |
24 files (29,813K bytes) |
| Messages: | 176,789 |
<https://www.flickr.com/gp/188240748@N05/0oS69B66P8>
Saw an Indian Scout 60 recently on hols. Reasonably inoffensive bike but
the speedo reads to 200mph!
My typical measurement of speedometer error on bikes tends toward the upper end of the allowable range, around 10 percent too optimistic.I blame the germans. If a speedometer shows less than real, the vehicle fails inspection. But it is allowed to show 10-15% more. The Opels I grew up with and the few german cars and MCs I have driven, all showed ~10% more.
[1] Both 1981 Hondas, a CM400T and a CB900C.My 80ies and 90ies japanese vehicles have all been within a needle width of reality, but from ~2000 the optimism have spread to maybe 5%. I still blame the germans.
My typical measurement of speedometer error on bikes tends toward theI blame the germans. If a speedometer shows less than real, the vehicle fails inspection. But it is allowed to show 10-15% more. The Opels I
upper end of the allowable range, around 10 percent too optimistic.
grew up with and the few german cars and MCs I have driven, all showed
~10% more.
In the UK I think C&U regs stated tolerances of +10% / -0% some time back, bit AFAIK it's not tested.I do not know the tolerance here, but I guess it has come to follow EU regulations. But the only thing tested is that the needle moves, when the vehicle starts moving. Up to (I think) the 90ies, MCs did not even need a speedometer. Or turn signals.
<https://www.flickr.com/gp/188240748@N05/0oS69B66P8>
Saw an Indian Scout 60 recently on hols. Reasonably inoffensive bike but
the speedo reads to 200mph!
On 11/10/2025 00:04, Bruce wrote:
<https://www.flickr.com/gp/188240748@N05/0oS69B66P8>I can't actually see the bit in the photo where it actually says 'mph' rather than (say) kph?
Saw an Indian Scout 60 recently on hols. Reasonably inoffensive bike
but the speedo reads to 200mph!
My typical measurement of speedometer error on bikes tends toward the upper end of the allowable range, around 10 percent too optimistic.I blame the germans. If a speedometer shows less than real, the vehicle fails inspection. But it is allowed to show 10-15% more. The Opels I grew up with and the few german cars and MCs I have driven, all showed ~10% more.
On 12/10/2025 12:49, chrisnd @ukrm wrote:
On 11/10/2025 00:04, Bruce wrote:
<https://www.flickr.com/gp/188240748@N05/0oS69B66P8>I can't actually see the bit in the photo where it actually says 'mph'
Saw an Indian Scout 60 recently on hols. Reasonably inoffensive bike
but the speedo reads to 200mph!
rather than (say) kph?
Ah yes, perhaps a cunning ploy by Indian to use the same speedo
regardless of where sold with just an ECU change?
My 80ies and 90ies japanese vehicles have all been within a needle width of reality
The interesting thing to me about that speedometer is its
non-linearity.
On 11/10/2025 15:47, H wrote:
My typical measurement of speedometer error on bikes tends toward theI blame the germans. If a speedometer shows less than real, the vehicle
upper end of the allowable range, around 10 percent too optimistic.
fails inspection. But it is allowed to show 10-15% more. The Opels I
grew up with and the few german cars and MCs I have driven, all showed
~10% more.
In the UK I think C&U regs stated tolerances of +10% / -0% some time
back, bit AFAIK it's not tested.
My bikes have had quite a range: typically around +5% but my first Guzzi about -8% and the Energica almost exactly +10% until one of the firmware updates made brought it down a bit.
In the UK I think C&U regs stated tolerances of +10% / -0% some time back, bit AFAIK it's not tested.I do not know the tolerance here, but I guess it has come to follow EU regulations. But the only thing tested is that the needle moves, when the vehicle starts moving. Up to (I think) the 90ies, MCs did not even need a speedometer. Or turn signals.
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never going to reach that far anyway.
Sqirrel99 <secret.sqirrel99@gmail.com> wrote:
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never
going to reach that far anyway.
I was remarking on the difference in the 20 mph spans 20-40 and
100-120, not the obviously fantasy markings past 120.
On Mon, 13 Oct 2025 14:34:33 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
Sqirrel99 <secret.sqirrel99@gmail.com> wrote:
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never >>> going to reach that far anyway.
I was remarking on the difference in the 20 mph spans 20-40 and
100-120, not the obviously fantasy markings past 120.
I would assume that anything vaguely modern would have an electronic
speedo, not mechanical, so I wouldn't see anything odd about it.
[0] Digital-only speedometers and tachometers [snip]
[1] Norman, Donald A. (2013). The [snip]
Sqirrel99 <secret.sqirrel99@gmail.com> wrote:
Mark Olson wrote:
The interesting thing to me about that speedometer is itsI doubt the speedo is non-linear, just the legend - the needle is never
non-linearity.
going to reach that far anyway.
I was remarking on the difference in the 20 mph spans 20-40 and
100-120, not the obviously fantasy markings past 120.
There are two types of people in the world:
1) Those who start numbering lists from one
1) Those who start numbering lists from zero.
On 13/10/2025 19:16, Mark Olson wrote:
[0] Digital-only speedometers and tachometers [snip]
[1] Norman, Donald A. (2013). The [snip]
There are two types of people in the world:
1) Those who start numbering lists from one
1) Those who start numbering lists from zero.
On 13/10/2025 19:16, Mark Olson wrote:
[0] Digital-only speedometers and tachometers [snip]
[1] Norman, Donald A. (2013). The [snip]
There are two types of people in the world:
1) Those who start numbering lists from one
1) Those who start numbering lists from zero.
Bruce <07.013@scorecrow.com> wrote:
On 12/10/2025 12:49, chrisnd @ukrm wrote:
On 11/10/2025 00:04, Bruce wrote:
<https://www.flickr.com/gp/188240748@N05/0oS69B66P8>I can't actually see the bit in the photo where it actually says 'mph'
Saw an Indian Scout 60 recently on hols. Reasonably inoffensive bike
but the speedo reads to 200mph!
rather than (say) kph?
Ah yes, perhaps a cunning ploy by Indian to use the same speedo
regardless of where sold with just an ECU change?
AFAIK, the display is switchable from miles to km by holding in a
button while switching on the ignition.
The interesting thing to me about that speedometer is its
non-linearity.
Bruce <07.013@scorecrow.com> wrote:
On 13/10/2025 19:16, Mark Olson wrote:
[0] Digital-only speedometers and tachometers [snip]
[1] Norman, Donald A. (2013). The [snip]
There are two types of people in the world:
1) Those who start numbering lists from one
1) Those who start numbering lists from zero.
VBG
P.S. My hobgoblin noticed the lack of a full stop at the end of
note 1).
On Sat, 11 Oct 2025 16:47:14 +0200, H <donotremovespam@outlook.com>
wrote:
My typical measurement of speedometer error on bikes tends toward the upper end of the allowable range, around 10 percent too optimistic.I blame the germans. If a speedometer shows less than real, the vehicle fails inspection. But it is allowed to show 10-15% more. The Opels I grew up with and the few german cars and MCs I have driven, all showed ~10% more.
My 2021 R1250RS shows about 2% high.
The +10% gives some scope for different wheel/tyre combinations not
having exactly the same diameter, and will absorb any tyre 'growth' at
high speed.
The -0% removes the possibility of speedo reading error as a speeding defense.
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never going to reach that far anyway.
Sqirrel99 <secret.sqirrel99@gmail.com> wrote:
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never
going to reach that far anyway.
I was remarking on the difference in the 20 mph spans 20-40 and
100-120, not the obviously fantasy markings past 120.
On 13/10/2025 19:16, Mark Olson wrote:
[0] Digital-only speedometers and tachometers [snip]
[1] Norman, Donald A. (2013). The [snip]
There are two types of people in the world:
1) Those who start numbering lists from one
1) Those who start numbering lists from zero.
On 12/10/2025 16:42, Mark Olson wrote:
Aha! That explains a lot.
The interesting thing to me about that speedometer is its
non-linearity.
Yes, but not so much the non-linearity (which I seem to remember being
quite common at one time) but the fact that there seems to be a step
change in linearity above 120 rather than a gradual shift?
On 14/10/2025 15:25, chrisnd @ukrm wrote:
On 12/10/2025 16:42, Mark Olson wrote:
Aha! That explains a lot.
The interesting thing to me about that speedometer is its
non-linearity.
Yes, but not so much the non-linearity (which I seem to remember being
quite common at one time) but the fact that there seems to be a step
change in linearity above 120 rather than a gradual shift?
If you're thinking back to the olden days of cup-and-magnet speedos,
maybe they were non-linear, being fairly simple electro-mechanical
analogue devices. Eddy currents are probably affected by resistance
which is affected by temperature (which might rise with faster rotation
and higher currents) and there could be weird magnetic hysteresis
effects, maybe. Possibly. I imagine the spring would be fairly linear.
PipL <pip@nowhere.nul> wrote:
If you're thinking back to the olden days of cup-and-magnet speedos,
maybe they were non-linear, being fairly simple electro-mechanical
analogue devices. Eddy currents are probably affected by resistance
which is affected by temperature (which might rise with faster rotation
and higher currents) and there could be weird magnetic hysteresis
effects, maybe. Possibly. I imagine the spring would be fairly linear.
As the years have gone by, I have gained a lot of respect for what
engineers were capable of achieving in the pre-digital and pre-solid
state era.
There have always been some rather clever folks out there,
capable of solving tricky problems in elegant and robust ways, with
whatever level of technology was available to them.
Nowadays, it's possible to throw a lot of computing power at a> problem for not a lot of money, which tends to encourage somewhat
less elegant solutions.
For some reason, the Harrison timekeepers come to mind.
On 14/10/2025 22:41, Mark Olson wrote:
For some reason, the Harrison timekeepers come to mind.
Ooh, not heard of those <Googles> oh, *those*, ship chronometers. I have seen an article about them (possibly also in a museum) but it was many
years ago. I do like clock mechanisms, even built a crude one though the escapement was utter rubbish. It ran, sort of, for as long as half an
hour sometimes! Think I got the period out by a factor of 2 as well. I
keep meaning to revisit that.
On 13/10/2025 15:34, Mark Olson wrote:
Sqirrel99 <secret.sqirrel99@gmail.com> wrote:
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never
going to reach that far anyway.
I was remarking on the difference in the 20 mph spans 20-40 and
100-120, not the obviously fantasy markings past 120.
I *think* my Energica is about +5% at 20 or below and higher at 40 or
more, according to roadside radar signs, but of course there's a +/- >half-a-count lack of precision on both the speedo and the sign.
PipL <pip@nowhere.nul> wrote:
On 14/10/2025 22:41, Mark Olson wrote:
For some reason, the Harrison timekeepers come to mind.
Ooh, not heard of those <Googles> oh, *those*, ship chronometers. I have
seen an article about them (possibly also in a museum) but it was many
years ago. I do like clock mechanisms, even built a crude one though the
escapement was utter rubbish. It ran, sort of, for as long as half an
hour sometimes! Think I got the period out by a factor of 2 as well. I
keep meaning to revisit that.
When I was over the pond for TOG's funeral, I made a point of visiting >Greenwich Observatory so I could see them for myself. Not to be missed
if you're a bit of a tech nerd, also plenty of other interesting clocks >(sidereal time, atomic, etc.) scattered about the place.
I recommend the book "Longitude" by Dava Sobel, and the TV mini-series
based on it.
Sobel, Dava. Longitude: The True Story of a Lone Genius Who Solved
the Greatest Scientific Problem of His Time. Bloomsbury Publishing
Plc, 2010.
https://en.wikipedia.org/wiki/Longitude_(book)#
https://www.imdb.com/title/tt0192263
On 11/10/2025 15:47 H penned these words:
My 80ies and 90ies japanese vehicles have all been within a needle width of reality
The current car is according to both the SatNag and those helpful roadside signs
that tell you you approach speed bang on accurate.
Mark Olson wrote:
The interesting thing to me about that speedometer is its
non-linearity.
I doubt the speedo is non-linear, just the legend - the needle is never going to reach that far anyway.
Not sure about the UK these days, but every roadside speed displayThe ones here, not-UK, agrees with Garmin. But until ~15 years ago, they often gave wild measurements for MCs, if they even registrered. I was always a little nervous, that the ticket mailing ones would do the same.
I've ever seen is itself 5-10% higher than real GPS speed
OTOH, there is/was a lot of clevernes to admire in LORAN, Decca and GPS, that made daily life easier than clocks, sextants and tables.Ooh, not heard of those <Googles> oh, *those*, ship chronometers.
Not sure about the UK these days, but every roadside speed display
I've ever seen is itself 5-10% higher than real GPS speed,
On 15/10/2025 15:46 Ace penned these words:
Not sure about the UK these days, but every roadside speed display
I've ever seen is itself 5-10% higher than real GPS speed,
Certainly those I've come upon recently in the UK tie up with both the
GPS and the car.
same on a recent trip in France, where there also seems to be a rise in the >number of those traffic lights 100m down the road from where the 50 or >increasingly 30kph speed limit starts. Go slightly over the speed limit and >they stay red until you stop. Spain has these too.
OTOH, there is/was a lot of clevernes to admire in LORAN, Decca and GPS, that made daily life easier than clocks, sextants and tables.Ooh, not heard of those <Googles> oh, *those*, ship chronometers.
PipL <pip@nowhere.nul> wrote:
On 14/10/2025 22:41, Mark Olson wrote:
For some reason, the Harrison timekeepers come to mind.
Ooh, not heard of those <Googles> oh, *those*, ship chronometers. I have
seen an article about them (possibly also in a museum) but it was many
years ago. I do like clock mechanisms, even built a crude one though the
escapement was utter rubbish. It ran, sort of, for as long as half an
hour sometimes! Think I got the period out by a factor of 2 as well. I
keep meaning to revisit that.
When I was over the pond for TOG's funeral, I made a point of visiting Greenwich Observatory so I could see them for myself. Not to be missed
if you're a bit of a tech nerd, also plenty of other interesting clocks (sidereal time, atomic, etc.) scattered about the place.
I recommend the book "Longitude" by Dava Sobel, and the TV mini-series
based on it.