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Thread: Which is correct?

  1. #1

    Which is correct?

    My GPS trip info is always different from my odometer. In other words, if I set my GPS mileage to 0 and the odometer to 0 at the start of a ride, why is the mileage reading always different when you compare the two? Also, my mileage is always different (at least 10-15 miles)from other bikes ridden the exact same number of miles. Which is accurate? Thanks, Gail
    Gail Thorne
    2017 F700GS

  2. #2
    Quote Originally Posted by shortythorne View Post
    My GPS trip info is always different from my odometer. In other words, if I set my GPS mileage to 0 and the odometer to 0 at the start of a ride, why is the mileage reading always different when you compare the two? Also, my mileage is always different (at least 10-15 miles)from other bikes ridden the exact same number of miles. Which is accurate? Thanks, Gail
    Generally the GPS distance is very accurate. This is most true on the straightest roads. In heavy woods, canyons, and urban canyons amidst tall buildings sometimes it gets a little off. Our experience on lots of bikes is that over or under counting by the bike's odometer can often be in the 3% to 4% range, and on occasional bikes a bunch more than that. I trust my GPS and other than the tripmeter for gas stops pretty much ignore the odometer. There was one case where a guy threatened to sue BMW because he thought his 36,000 mile warranty ran out 5% or so too soon.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  3. #3
    Quote Originally Posted by shortythorne View Post
    My GPS trip info is always different from my odometer. In other words, if I set my GPS mileage to 0 and the odometer to 0 at the start of a ride, why is the mileage reading always different when you compare the two? Also, my mileage is always different (at least 10-15 miles)from other bikes ridden the exact same number of miles. Which is accurate? Thanks, Gail
    Is the GPS consistently higher or lower than than the odometer, or is there no pattern?

    Is it your GPS mileage, or your odometer that is different from those you ride with? Is it 10-15 miles higher, or lower?

  4. #4
    Quote Originally Posted by vark View Post
    Is the GPS consistently higher or lower than than the odometer, or is there no pattern?

    Is it your GPS mileage, or your odometer that is different from those you ride with? Is it 10-15 miles higher, or lower?
    My GPS is always higher mileage than the odometer.The odometer is different from those I ride with, and is lower.
    Gail Thorne
    2017 F700GS

  5. #5
    Quote Originally Posted by PGlaves View Post
    Generally the GPS distance is very accurate. This is most true on the straightest roads. In heavy woods, canyons, and urban canyons amidst tall buildings sometimes it gets a little off. Our experience on lots of bikes is that over or under counting by the bike's odometer can often be in the 3% to 4% range, and on occasional bikes a bunch more than that. I trust my GPS and other than the tripmeter for gas stops pretty much ignore the odometer. There was one case where a guy threatened to sue BMW because he thought his 36,000 mile warranty ran out 5% or so too soon.
    Thanks Paul!
    Gail Thorne
    2017 F700GS

  6. #6
    Liaison 20774's Avatar
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    Have you ever calibrated your odometer to the mileage markers on the Interstate? For those of us with few farkles, this is something we do to while away the time! Do it over a good distance like 5 or 10 miles. That will give you another independent data point for comparison.

    The GPS just has to deal w/ sattelite lock and coverage. But your odometer deals with several mechanical issues including tire size, drive ratios, etc.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  7. #7
    Quote Originally Posted by shortythorne View Post
    My GPS is always higher mileage than the odometer.The odometer is different from those I ride with, and is lower.
    So the odometer consistently reads lower than the GPS and other riders’ odometers. Got it.

    In my experience, when riding on 2-wheels GPS usually gives a LOWER mileage readout than the odometer. This is usually attributed to the way GPS plots positions at a designated sample rate, and then measures the distance between those points by connecting them with straight lines, rather than exactly measuring the path taken by the vehicle. Whereas the odometer is measuring the distance travelled by the tire as it rolls over the exact path taken by the bike.

    So your results are - - opposite. It could just be a minor design flaw or poorly calibrated odometer. Another variable that can affect odometer readings is if the tires have been changed from the oem spec size. Tire pressure and payload can also increase or decrease the wheel/tire radius, which in turn alters the tire circumference measurement that the odometer’s calibration is based on.

    From my perspective, having a “low” reading on the odometer is better than the alternative.

  8. #8
    SURVIVOR akbeemer's Avatar
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    My GPS mileage is always more than the odometer. Maybe 10-13 miles over a 1000 miles.
    Kevin Huddy
    The Outpost, Silver City, Montana

  9. #9
    On our G310GSs both odometers are within 1/2 of 1% of the GPS miles, and they both read the same: that is on a 500 mile or more day they will accumulate exactly the same number of miles. They are the first BMW odometers I consider to be accurate.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

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