Page 5 of 7 FirstFirst ... 34567 LastLast
Results 41 to 50 of 64

Thread: Top speed frustration

  1. #41
    Senior Member Top speed frustration ld_rider's Avatar
    Bike: 2014 Black ABS/DCT
    Join Date
    Apr 2014
    Location
    New England
    Posts
    760
    It might be easier to make an instrument that measures miles per hour more accurate than an instrument that measures kilometers per hour.

    Think of measuring distance with a ruler using units of half and inch. You can only be accurate to within half and inch.

    Compare the accuracy of that same ruler with one using units of a thousandths of an inch. You can be accurate within a thousandths of an inch

    Miles and Kilometers are a similar situation:


    A speedometer that is off at 100 mph by 5% will only be traveling at 95, an error of 5 mph.

    A speedometer that is off at 100 kmh by 5 % will only be traveling at 95 km/h, an error of about 3 mph

    Both will have the same percentage of error, but one is significantly more accurate than the other.
    Rob in New England
    IBA# 540

  2. #42
    Super Moderator Top speed frustration 670cc's Avatar
    Bike: NC700X, GL1800, KLX140G, CRF250L Rally, Ruckus 50
    Join Date
    Aug 2012
    Location
    USA
    Posts
    6,441
    Quote Originally Posted by ld_rider View Post
    It might be easier to make an instrument that measures miles per hour more accurate than an instrument that measures kilometers per hour.

    Think of measuring distance with a ruler using units of half and inch. You can only be accurate to within half and inch.

    Compare the accuracy of that same ruler with one using units of a thousandths of an inch. You can be accurate within a thousandths of an inch

    Miles and Kilometers are a similar situation:


    A speedometer that is off at 100 mph by 5% will only be traveling at 95, an error of 5 mph.

    A speedometer that is off at 100 kmh by 5 % will only be traveling at 95 km/h, an error of about 3 mph

    Both will have the same percentage of error, but one is significantly more accurate than the other.
    Don’t confuse the term accuracy with resolution or precision.

    No one said we were limited to whole numbers. On the speedometer, simply display either the English or the metric speed to a resolution of one decimal place and the English units have no practical advantage over metric units. Accuracy (displayed vs actual speed) on the other hand, is all in the hands of the speedometer’s design and implementation.
    Greg
    GWRRA Member
    AMA Life Member
    "230,000 Mile Club"

    NanCyX . . . . . . . . . . The 250

  3. #43
    Senior Member Top speed frustration ld_rider's Avatar
    Bike: 2014 Black ABS/DCT
    Join Date
    Apr 2014
    Location
    New England
    Posts
    760
    Quote Originally Posted by 670cc View Post
    Don’t confuse the term accuracy with resolution or precision.
    Or percentage of error with accuracy ;-)
    Rob in New England
    IBA# 540

  4. #44
    Senior Member Dennis M's Avatar
    Bike: '13 NC700X, '09 Moto Guzzi V7 Classic
    Join Date
    Jul 2013
    Location
    Independence, MO.
    Posts
    243
    When I had my Burgman 650 it's speedometer read 10% high at all speeds, and most everybody on the Burgman forum reported the same. Both from checking against GPS and those "your speed is" signs that are periodically placed out on the road to try to get people to slow down.
    I'm not smart enough for a smart phone, so all I have is a dumb phone.
    GPS? Why would I want one of them? You can't get lost, there's no fun in that.

  5. #45
    Senior Member Top speed frustration ld_rider's Avatar
    Bike: 2014 Black ABS/DCT
    Join Date
    Apr 2014
    Location
    New England
    Posts
    760
    Quote Originally Posted by ld_rider View Post
    Or percentage of error with accuracy ;-)
    Ok, here I am replying to my own reply ..how weird it that?

    Upon further review my posts make zero sense and even less logical sense. An error of 5 percent is an error of 5 percent. Makes no difference if Km or Miles. In my long winded reply one of my errors was using two different speeds and comparing the errors. 100 miles per hour isn't the same speed as 100 Km an hour. Obviously, the faster vehicle will cover more miles and have a larger "error distance" than a slower vehicle. Duh!

    With equal speeds the distance errors would be the same.....and their accuracy.

    Back to your regularly scheduled thread .....
    Last edited by ld_rider; 10th January 2019 at 13:31.
    Rob in New England
    IBA# 540

  6. #46
    Member Top speed frustration New Commuter700's Avatar
    Bike: NC700X
    Join Date
    May 2018
    Location
    San Tan Valley, AZ
    Posts
    59
    Quote Originally Posted by Dennis M View Post
    When I had my Burgman 650 it's speedometer read 10% high at all speeds, and most everybody on the Burgman forum reported the same. Both from checking against GPS and those "your speed is" signs that are periodically placed out on the road to try to get people to slow down.
    I worked for a rental car company in the '90s and I noticed that every single Dodge Dynasty was off by around 10 percent. I am convinced to this day that they did that not for the speedo but for the odometer, so that the warranty miles would go by faster.


    https://tinkergr.wixsite.com/website

  7. #47
    Senior Member Top speed frustration dduelin's Avatar
    Bike: NC700XD, ST1300, Elite 80
    Join Date
    Jul 2012
    Location
    North FL USA
    Posts
    3,680
    Quote Originally Posted by New Commuter700 View Post
    I worked for a rental car company in the '90s and I noticed that every single Dodge Dynasty was off by around 10 percent. I am convinced to this day that they did that not for the speedo but for the odometer, so that the warranty miles would go by faster.
    The odometer often exhibits less variance than the speedometer. Error of 4% or less is considered within bounds of convention.
    Dave

    GL1800
    NC700XD




  8. #48
    Member dreamer's Avatar
    Bike: Honda NC750D Integra
    Join Date
    Jun 2017
    Location
    Bratislava, Slovakia
    Posts
    57
    The EU legislature on speedometer accuracy for motorcycles:

    The production shall be deemed to conform to this Regulation if the following relationship between the speed indicated on the display of the speedometer (V1) and the actual speed (V2) is observed:

    in the case of vehicles of categories L3 (i.e. motorcycles), L4 and L5:

    0 ≤ (V1 V2) ≤ 0,1 V2 + 8 km/h;

    So what that means is that the speed indicated can never be less than the actual speed and cannot be higher than 10% of actual speed + 8 km/h. All motorcycles (stock) I had to date were within this spec.
    Last edited by dreamer; 13th January 2019 at 04:23.

  9. #49
    Member
    Bike: SV,WR,YZ,NC
    Join Date
    Jan 2019
    Location
    CA
    Posts
    42
    Quote Originally Posted by New Commuter700 View Post
    I worked for a rental car company in the '90s and I noticed that every single Dodge Dynasty was off by around 10 percent. I am convinced to this day that they did that not for the speedo but for the odometer, so that the warranty miles would go by faster.
    I know on Suzuki SVs there's a significant difference between what speedo says and what odo says (approximately 8% between the two), with odo being essentially spot on. Wouldn't surprise me if the Dynasty was similar.
    Quote Originally Posted by dreamer View Post
    The EU legislature on speedometer accuracy for motorcycles:

    The production shall be deemed to conform to this Regulation if the following relationship between the speed indicated on the display of the speedometer (V1) and the actual speed (V2) is observed:

    in the case of vehicles of categories L3 (i.e. motorcycles), L4 and L5:

    0 ≤ (V1 V2) ≤ 0,1 V2 + 8 km/h;

    So what that means is that the speed indicated can never be less than the actual speed and cannot be higher than 10% of actual speed + 8 km/h. All motorcycles (stock) I had to date were within this spec.
    Wow, that's a massive difference.

    Do you know what odo is allowed to be off by?

  10. #50
    Member dreamer's Avatar
    Bike: Honda NC750D Integra
    Join Date
    Jun 2017
    Location
    Bratislava, Slovakia
    Posts
    57
    Yes, it is huge. On my Aprilia scooter I was doing max speed of 149 km/h indicated, 135 km/h GPS. The difference was 14 km/h, which was still within spec according to this ((135+8)/10=14.3).

    I could not find any info on odometers, but I always believed, that speedometer is related to odometer. I know this may not be true in all cases, but at least for NC isn't there only one sensor for speedo/odo?

Similar Threads

  1. Add Speed limit and current speed to Google maps with this app
    By netizen in forum NC700 General Discussion
    Replies: 11
    Last Post: 18th April 2016, 06:45
  2. Maintaining speed....
    By pprior in forum NC700 General Discussion
    Replies: 9
    Last Post: 22nd May 2014, 17:44
  3. Cruising speed
    By nrsheikh in forum NC700 General Discussion
    Replies: 32
    Last Post: 5th March 2014, 21:33
  4. What's your top speed?
    By dduelin in forum NC700 General Discussion
    Replies: 39
    Last Post: 8th January 2014, 11:10
  5. speed
    By mcbridedl in forum NC700 General Discussion
    Replies: 12
    Last Post: 6th July 2013, 13:04

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •