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Thread: speedo accuracy on your R-1150-RT

  1. #1
    You stupid, fix it! r11rs94's Avatar
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    speedo accuracy on your R-1150-RT

    I just receintly installed a ZUMO on my RT. Noticed the speedo approx 4MPH higher than the GPS unit reads. From what I've read on past threads< I was expecting much worse. What say you other RT riders with GPS.
    The thing about traveling is, you never want it to end and you can't wait to get home.
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    04 R-1150-RT current bike. 94 R-1100-RS74,383, Sold, 78 R-80/7, K.I.A by a D.U.I
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  2. #2
    Love this RT! tkbaker4's Avatar
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    About the same on my RS.
    Tom Baker
    2009 BMW R1200RT
    1970 Triumph Bonneville

  3. #3
    DrPaul DrPaul's Avatar
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    4 mph is exactly the gradient between my R1150RT speedo and my Zumo 550 with the speedo reading higher. BMW gets an "A" for precision and a "C" for accuracy. That's probably saved me a few speeding tickets!

    DrPaul

  4. #4
    Registered User kgadley01's Avatar
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    speedo accuracy

    my 99 RT reads 4 mph fast. I don't have one of those zomo things. I still trust a good old American roadmap. now this is for everyone else that doesn't have one of those zomo things. to check your speed, time yourself between mile markers on the super slab. divide the seconds INTO 3600, this will give you your true speed.

  5. #5
    Registered User awagnon's Avatar
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    Mine is about 5% off of whatever speed I'm going. If I'm going 50 mph, it's about 2.5 mph off. About 4 mph off at 70 mph. etc. It's the law that they read high and never low.

    My son-in-law had a speedometer on his V-Strom that read about 6-7 mph high. He found someone who made perfectly matching dial faces to replace the original that corrected the error. After he replaced the face, it was exactly on the money.

    I used the speedo on the GPS most of the time anyway.
    Al - Ogden, Utah
    Boxer bikes, boxer dogs, and letterboxing.
    2004 1150RT and 2018 Triumph Tiger 800xrx

  6. #6
    Registered User ANDYVH's Avatar
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    I think that ANY cable driven speedometer on ANY brand motorcycle is going to read something like 5% to 10% off the actual cycke speed. Its just the nature of a cable driven speedo. Electronic speedometers reading from a magnet sensor on the front wheel would be much more accurate. But the manufacturers, Japan, US (Harley) or German have gotten by cheap for decades using cable driven speedos.

    Just the nature of the beast and what the market will put up with.

    The speedometer on my R1100RS has always read about 5mph higher than my actual speed and it really doesn't bother me one bit.
    Get trained! The best "performance" upgrade you can get is YOU. Visit msf-usa.org for training info.

  7. #7
    Rally Rat
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    Smile

    Not to buck the trend, but mine actually reads 3.1% in the other direction.

    When the speedometer indicates 70 MPH, I'm actually traveling about 72 MPH. Also means I have more miles on my bike than the odometer indicates (a 'Plus' for purposes of my 3 - Yr. Warranty!).

    As for ..."it's the law that they read high and never low."

    That's a new one to me. Does this happen to be a Federal Statute that I am unaware of, and could the author of that post quote me the federal number (for research purposes only - not kicking sand in anyone's face).

    No such law here in WI. Never was brought up in court by even the smartest lawyers (oxymoron alert here!) for what few individuals, of the hundreds of speeding citations I issued over my career, contested any ticket. Never lost.

    And by the way, as for those hundreds of citations, they were never BMW riders, MOA members and they were all bad people.
    Last edited by Greenwald; 04-08-2008 at 05:17 PM.

  8. #8
    Registered User ANDYVH's Avatar
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    For those who must have a an accurate speedometer, inexpensively, get a quality bicycle speedometer/computer and install it on your motorcycle. Brands like Cateye or Sigma offer many features, some are even wireless, and once the comupter is calibrated to the tire size they are very accurate.

    Since my speedometer reads about 5mph high, it automatically keeps my actual speed in ranges that don't even interest the officers. My speedo says 75 when I actually am doing about 71, good for a 65 mph speed limit.

    Surprisingly, my odometer is much more accurate.
    Get trained! The best "performance" upgrade you can get is YOU. Visit msf-usa.org for training info.

  9. #9
    Republic of Texas
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    Quote Originally Posted by awagnon View Post
    Mine is about 5% off of whatever speed I'm going. If I'm going 50 mph, it's about 2.5 mph off. About 4 mph off at 70 mph. etc. It's the law that they read high and never low.
    "The law"? I think it may be "BMW's Law", i.e., it is something that BMW does to all of its vehicles. According to my Garmin 276C Plus, my Z3 reads about 4% high, but my Jeep Liberty reads dead on (less than 1 mph difference at all speeds).
    Mike White
    MOA Life Time Member #57882
    '13 K1300S "30 Years", '95 R1100RS, '88 K75S, '97 Ducati 916, '95 Ducati 900SS CR. Gone, but not forgotten, '75 R90S

  10. #10
    Registered User rmarkr's Avatar
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    Speedo

    Both my BMW's read 5mph high throughout the range. The mileometers are almost dead on. (vs the Zumo). Fitting a non-stock rear tire will obviously alter things.
    I suspect the error is designed in for legal protection.
    Mark

    "Of all the things I've lost, I miss my mind the most" Mark Twain

  11. #11
    Registered User Fritzc's Avatar
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    Thumbs up Dead on!

    According to my Garmin Street Pilot, My speedometer (R1100RT-Police Bike) is dead on accurate at any speed. Is there a margin of error for GPS?
    There are two things to aim at in life; first to get what you want, and after that to enjoy it. Only the wisest of mankind achieve the second. -Logan Pearsall Smith, essayist (1865-1946)

  12. #12
    Rally Rat
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    Smile

    Quote Originally Posted by Fritzc View Post
    According to my Garmin Street Pilot, My speedometer (R1100RT-Police Bike) is dead on accurate at any speed. Is there a margin of error for GPS?
    Unlikely. Garmin makes a quality product.

    Their units routinely 'capture' 8 - 12 of the geosynchronous satellite signals, providing such precise triagulation, that I would believe what your GPS is telling you, and rejoice that you own one of the rare BMW's with a perfectly accurate speedometer!

  13. #13
    Seattle-area Rounder OfficerImpersonator's Avatar
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    Mine is dead-on - and verified by my GPS.

    But then, my speedo is certified
    Seattle, WA
    2012 R1200GSA
    2002 R1150RT-P
    1992 K75S sold

  14. #14
    Registered User kgadley01's Avatar
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    speedo accuracy

    if you own any police model your speedo should be accurate. a friend of mine has some aftermarket gadget on his goldwing that makes his speedo dead on. I don't know if they make them for BMWs or not.

  15. #15
    I'm about 5% high. Interestingly, the error is less when it is cold out.
    Frank G.
    Hattiesburg, Mississippi
    2004 R1150RT

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