Etrex Vista Speed Accuracy

[+Minex]

Has anyone had issues with the accuracy of the Etrex Vista? I haven't proven it yet, but it doesn't appear to be accurate. When on my motorcycle, its reporting about 20% slower than the speedometer on the bike. ie, when the speedometer is reading 50 MPH, the Vista shows 40. The problem is that the speedometer on the bike isn't accurate either. I had someone try it in their truck and it seems to be reporting 5 MPH slower.

 

Is there a better way to test this or collaborate the unit? Has anyone else run into this issue?

[+tirediron]

there is a generally accepted error factor of up to 10% on vehicle speedometers. The only way to get a true measure of whether or not your GPSr is accurate would be to drive for a known distance at a set speed and do the math. Between the two of them, my $$$ say that the truck's speedo is high, not vice versa.

[+Tahoe Skier5000]

Your GPS is the accurate source. Automobile speedometers are intentionally set high to give a false impression of speed for the driver.

[MacBandit]

Your GPS is the accurate source. Automobile speedometers are intentionally set high to give a false impression of speed for the driver.

Actually it's to protect the manufacturer from lawsuits from new car owners complaining about tickets due to the speedo showing a lower speed then they were actually going. So all manufacturers seem to over compensate to a degree. This goes for cars and bikes.

[GeoTripper]

Actually it's to protect the manufacturer from lawsuits from new car owners complaining about tickets due to the speedo showing a lower speed then they were actually going.  So all manufacturers seem to over compensate to a degree.  This goes for cars and bikes.

Does this go for the odometer as well? Do they make it run higher so you think you're getting better gas mileage, you take it in for service more often, you decrease the value of your car more rapidly, etc? Very interesting....

[+Tahoe Skier5000]

Actually it's to protect the manufacturer from lawsuits from new car owners complaining about tickets due to the speedo showing a lower speed then they were actually going.  So all manufacturers seem to over compensate to a degree.  This goes for cars and bikes.

Does this go for the odometer as well? Do they make it run higher so you think you're getting better gas mileage, you take it in for service more often, you decrease the value of your car more rapidly, etc? Very interesting....

No, the odometer is set to the proper speed. If not, that would cause a whole new wave of lawsuits against the manufacturer.

 

All of these hidden secrets in cars...

[+Minex]

Yeah, I just verified the Vista last night with another GPS. Both units are displaying the same speed. Man, I never realized how off my motorcycle was.

[+StormCrow42]

The accuracy of your odometer (and for that matter your speedometer too) varies with the condition of your tires.

[GeoTripper]

The accuracy of your odometer (and for that matter your speedometer too) varies with the condition of your tires.

Yeah, tell me about it. I had tires on a used car I got that were larger than the manufacturer recommended. According to the timing method between mileposts the speedometer and the odometer were fairly accurate. Now I've put the correct size tires on it and my speedometer reads about 10 mph high. I've called around and it will cost several hundred dollars at a speedo shop to fix this. I have to assume that now my odometer is off as well.

 

Also (to bring this back to GPS), in these timing instances I saw that the two GPSr's I was playing with at the time were reading very accurate speeds (a Garmin eTrex Summit and a Magellan GPS 315).

[MacBandit]

The accuracy of your odometer (and for that matter your speedometer too) varies with the condition of your tires.

Yeah, tell me about it. I had tires on a used car I got that were larger than the manufacturer recommended. According to the timing method between mileposts the speedometer and the odometer were fairly accurate. Now I've put the correct size tires on it and my speedometer reads about 10 mph high. I've called around and it will cost several hundred dollars at a speedo shop to fix this. I have to assume that now my odometer is off as well.

 

Also (to bring this back to GPS), in these timing instances I saw that the two GPSr's I was playing with at the time were reading very accurate speeds (a Garmin eTrex Summit and a Magellan GPS 315).

Check your odometer as well but typically it's only the speedometer that reads optimistically. The odometers are typically all but right on.

 

If you're wondering I do have some experience in this field as motorcycle repair is my profession.

[SgtCacher]

I've only been involved in geo-caching for about 6 months now, but the most important lesson I have learned in that time is to use the GPSr as an estimate only-for everything! I have found my Vista to be highly inaccurate on everything from measuring distance over a known course, to altitude, to distance from a cache. I've posted here about the inaccuracies and have been told by those with much more experience than I to expect that.

[+JayFredMuggs]

I have checked the speedometers on two of my cars against the Etrex Legend and found them to be extremely accurate. I usually find a road that is less traveled and set the cruise control so I am at a steady speed, and the GPSr usually is right on with the speedo. I would trust the accuracy of the GPSr over the speedo.

Of course, there are times when my GPSr says that my maximum speed was 252 MPH when I know for a fact that I didn't exceed 60, but this is a rare occurence.