Speedometer Error - Response From Yamaha

 As copied from another forum here is the response from Yamaha in reply
to a question about speedometer accuracy, or the lack there of.
Without doing the math I am not convinced their explanation is valid.

*********************************************************
Good afternoon:

This is an issue that we as a manufacture have looked into. There are
really two separate issues:

1. speedometer readings can be optimistic

2. the odometer reading is "out" meaning the reading (at the time
taken) is recording a larger distance than actually travelled.

1. Every speedometer installed on every motor vehicle is optimistic
because
a) as a tire wears, it becomes smaller in diameter and revolves
faster. At the far end of the wear scale, we would not want to err on
the side of pessimistic and become the cause of an accident or a
speeding violation.

2. As stated previously, the tires wear and become smaller and so the
distance travelled per revolution becomes less. Most of the time the
odometer is calibrated to be (approximately) correct at about 50% wear
with correct tire pressure. Additionally, tire slip ratio must be
accounted for, so these things all prevent any vehicle from having a
totally correct odometer reading.

These issues have never been a concern in the past as there was no
true and relatively easy method for owners of vehicles to confirm
speed and distance. This can be easily confirmed by GPS signal with
the new technologies, however it should be noted that many of the
signals from the satellites do have error "built in" to prevent
pinpoint accuracy of homing devices.

Finally, we have produced these parts to be as accurate as possible
given the design of them and they do comply with existing expectations
of accuracy. Eventually, when the technology and cost considerations
allow, we may start to see changes made to vehicles that show speed
and distance calculated from GPS signals, but first we would have to
ensure the signals are clear at every point and not lose them as we do
now under cloud cover or in tunnels etc.

Regards,

Scott

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

--
Remember

It is the VETERAN , not the preacher,
who has given us freedom of religion.

It is the VETERAN , not the reporter,
who has given us freedom of the press.

It is the VETERAN , not the poet,
who has given us freedom of speech.

It is the VETERAN , Not the Campus Organizer
who has given us freedom to assemble.

It is the VETERAN, not the lawyer,
who has given us the right to a fair trial.

It is the VETERAN , not the politician,
Who has given us the right to vote.

 On Oct 2, 7:17 pm, Calgary

LOL! Accurate as possible. So Yamaha thinks we're all stupid!
What a flippin' load of crap that was! :-)
--
Rayvan

 On Tue, 02 Oct 2007 20:30:57 -0700, Rayvan


Either it's a load of crap or they are admitting they can't calibrate
a simple device as well as any car, truck or some other brands of
motorcycles on the road.
  

--
Remember

It is the VETERAN , not the preacher,
who has given us freedom of religion.

It is the VETERAN , not the reporter,
who has given us freedom of the press.

It is the VETERAN , not the poet,
who has given us freedom of speech.

It is the VETERAN , Not the Campus Organizer
who has given us freedom to assemble.

It is the VETERAN, not the lawyer,
who has given us the right to a fair trial.

It is the VETERAN , not the politician,
Who has given us the right to vote.

 On Oct 2, 8:53 pm, Calgary

What they didn't mention was that accuracy of a motorcycle
speedo changes depending on whether the bike is leaned
over or upright, as the effective diameter of the wheel changes
when the bike is leaned.

I went through this exercise a while back with a bicycle speedo.
After a while, it occurred to me that calibration was going to
vary somewhat with the road.

The part about optimism/pessimism with tire wear is exactly
backwards, as others have pointed out.

Buy a Sigma bike speedo and calibrate it however you like.

 On Wed, 03 Oct 2007 14:34:44 -0700, Rob Kleinschmidt


I use a GPS and ride comfortable knowing how fast I am going.

I have heard of the Sigma before and it's not a bad idea to use one,
if you tend to push to the limit, the tolerances of the local traffic
enforcement.
  

--
Remember

It is the VETERAN , not the preacher,
who has given us freedom of religion.

It is the VETERAN , not the reporter,
who has given us freedom of the press.

It is the VETERAN , not the poet,
who has given us freedom of speech.

It is the VETERAN , Not the Campus Organizer
who has given us freedom to assemble.

It is the VETERAN, not the lawyer,
who has given us the right to a fair trial.

It is the VETERAN , not the politician,
Who has given us the right to vote.