Greetings. I've noticed that my Navigator V unit consistently displays between 2-4mph faster than the speedometer on the regular / standard display. It may not matter really but was 1). Surprised that the Navigator doesn't seem to be using information sent from the bike for this statistic (as it must for other things, ie. odometer, miles to re-fuel etc., etc.). Is the Navigator figuring out the MPH on its own through its GPS perhaps? 2. Wondering if anyone else has experienced this or could offer insight. Again, I'm not sure its a big enough thing to worry about but perhaps there are other aspects I should be considering and have not thought of. Thanks. Cheers! (BTW: Bike is a s1000xr, 2016)
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Navigator V vs. Speedometer Difference ???
- Thread starter tzc1999
- Start date
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- Tags
- navigator v odometer s1000xr
akbeemer
SURVIVOR
Yup - GPS.
ALL motorcycle speedometers are degraded 3-7% at the time of manufacturing.
You can research why, as commenting here would be tantamount to "an oil thread!"
Now wait a darn minute. GPSs do not have oil in them.
Mark H
New member
I was thinking the exact same thing on the weekend.
I was driving in my car, which has a built-in Sat Nave system, and it matches the speed on the Sat Nav to the speed displayed on the cars speedometer.
On my 2015 R1200GS with the NAV-V I see differences in the displayed speed (My GPS says I'm going slower than the speedometer).
BMW and/or Garmin have made the choice not to match the two and this may or may not be the best thing, but it is what it is.
As to why, well at the risk of opening a can of worms, I am of the opinion that a GPS is only so accurate at location (to within a couple of metres/yards at best unless you are military and dropping bombs). As for moving object, possibly less so and fluctuates.
The speedometer is (as many have said) set to read faster than your actual speed to accommodate a range of factors and still be on the "safe" side.
Rolling circumference apart from simple accuracy of the equipment is the key factor when it comes to the bikes ability to read speed and distance traveled, because the bike is actually not in truth reading either. As I understand it, it is reading the number of rotations of the wheel. This is very precise, but the variations occur between that measurement and the road surface.
I was driving in my car, which has a built-in Sat Nave system, and it matches the speed on the Sat Nav to the speed displayed on the cars speedometer.
On my 2015 R1200GS with the NAV-V I see differences in the displayed speed (My GPS says I'm going slower than the speedometer).
BMW and/or Garmin have made the choice not to match the two and this may or may not be the best thing, but it is what it is.
As to why, well at the risk of opening a can of worms, I am of the opinion that a GPS is only so accurate at location (to within a couple of metres/yards at best unless you are military and dropping bombs). As for moving object, possibly less so and fluctuates.
The speedometer is (as many have said) set to read faster than your actual speed to accommodate a range of factors and still be on the "safe" side.
Rolling circumference apart from simple accuracy of the equipment is the key factor when it comes to the bikes ability to read speed and distance traveled, because the bike is actually not in truth reading either. As I understand it, it is reading the number of rotations of the wheel. This is very precise, but the variations occur between that measurement and the road surface.
kthutchinson
Member
tzc1999,
In reply to your first question, how would the bike communicate to the Nav V? I don't believe the nav unit connects to the bike's data bus.
I find it interesting the your bike's indicated speed is slower than the GPS reading (I'm assuming the GPS is accurate). The accepted practice here in the US is to have the speedometer indicate faster than actual to avoid speeding tickets. I couldn't find a federal regulation on speedometer accuracy for motorcycles, but the SAE standard for electric speedometers, J1226, recommends a calibration within two percent (plus or minus) of the total indicated speed range, or a calibration within four percent with a bias toward reading high. And keep in mind that this is percentage of the maximum value displayed on the speedometer, not a percentage of the actual speed.
The European Union does have a speedometer standard. Speedometers cannot read slower than actual. For bikes with a maximum speed over 150 kph (93 mph), tests are conducted at 40, 80, and 120 kph and the errors on the fast side cannot exceed 1% + 4 kph. Your BMW should be built to this standard.
In reply to your first question, how would the bike communicate to the Nav V? I don't believe the nav unit connects to the bike's data bus.
I find it interesting the your bike's indicated speed is slower than the GPS reading (I'm assuming the GPS is accurate). The accepted practice here in the US is to have the speedometer indicate faster than actual to avoid speeding tickets. I couldn't find a federal regulation on speedometer accuracy for motorcycles, but the SAE standard for electric speedometers, J1226, recommends a calibration within two percent (plus or minus) of the total indicated speed range, or a calibration within four percent with a bias toward reading high. And keep in mind that this is percentage of the maximum value displayed on the speedometer, not a percentage of the actual speed.
The European Union does have a speedometer standard. Speedometers cannot read slower than actual. For bikes with a maximum speed over 150 kph (93 mph), tests are conducted at 40, 80, and 120 kph and the errors on the fast side cannot exceed 1% + 4 kph. Your BMW should be built to this standard.
lkraus
New member
Since at least 2005, BMW has provided a three conductor plug that connects to the Nav mount, providing 12VDC power and a speed pulse signal from the ZFE. I cannot say how Garmin actually uses that signal, but it is available for their use.
kthutchinson
Member
True. But I believe the speed signal is only used by the GPS when there aren't enough satellites in view to determine speed, as when riding through a tunnel.
Thanks all!
Thanks to all for the replies. Its good to know "its not just me". For curiosities sake, I need today to go and make sure I got the direction of the difference the correct way. I wrote the original post from memory (which for me can have its issues) and recalled the GPS being faster than the Bike speedometer. It would make more sense to be the other way around and perhaps I reversed the direction. Regardless, good information to know that these types of differences are, for lack of a better word, "normal".
Cheers!
Thanks to all for the replies. Its good to know "its not just me". For curiosities sake, I need today to go and make sure I got the direction of the difference the correct way. I wrote the original post from memory (which for me can have its issues) and recalled the GPS being faster than the Bike speedometer. It would make more sense to be the other way around and perhaps I reversed the direction. Regardless, good information to know that these types of differences are, for lack of a better word, "normal".
Cheers!
chewbacca
New member
Yup, me too. This is a variation on a theme. When I owned Triumphs there all kinds of threads on speedo being optimistic from 5-10%. That was before the widespread use of GPS. Similar threads were posted for a bunch of major brands. The seemingly unusual thing was the odometer was spot on. There were several gismos sold to adjust the speedo, but in every case if you got the speedo right the odometer changed as well. On my GS the the speedo is so small it's hard to compare it with my Nav V. I've got another post "GPS Speed in Turns" which points out that GPS isn't perfect either.
I've had a few motorcycles in the past, and there has always been the complaint that the speedometer is off. Then I bought a Honda NT700V and found the speedometer to be spot on. However, the MPG readout was a joke.
Something will always not be "perfect". I just adjust the MPH in my mind and ride with the traffic.
Chris
Something will always not be "perfect". I just adjust the MPH in my mind and ride with the traffic.
Chris
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