SpeedoHealer = Odometer Error

[V7Goose]

I don't have the speedohealer. My speedometer and odometer are both off but by different percentages. My speedometer is reads about 8% high and my odometer about 3.5% more miles. Got the same readings from a Lowrance iWay 500c and a Zumo 550. That would tend to support Leland's observations in the original post.

I agree with this. I have checked my speed and miles with a GPS and the stock speedometer on my 05 is off by about 8%, but the odometer is very close to accurate. I didn't write down all the numbers, but I plan to on my trip to the frozen north next week. My 07 was of by the same percentages as my 05.

Goose

[AKRefugee]

From my experience with GPS's and other navigation/distance measuring equipment I can tell you that the measurements on the GPS as compared the actual distance traveled on the surface may in fact be different. A GPS can not measure a curved line it can only measure a straight line. What it does is takes a reading and markes a point then it takes a second reading and makes a second mark. It than measures a straight line between those two points and that decomes the distance traveled. If you are traveling in an arc (corner) the straight line as measured between the two mark will actually cross to the inside of the arc and will show a shorter distance than what you travel in the arc. Since I do not know how to insert a drawing here you will have to do this yourself to see what I mean. First draw a circle. Then place a point at the the 10 o'clock position, this is your first "GPS point". Now place a point at the two o'clock position, this is your second "GPS point". Now draw a line between the two points, this is the "GPS distance traveled". As you can see it is shorter than if you were actual riding the circle line between the two points. If you were traveling at a higher rate of speed your points would be lets say at the 9 and 3 o'clock positions and therefore your error would be higher. How often your GPS takes a reading to set the points will affect the error rate. While this will usually be quite small it does add up. I would be willing to bet that folks that ride lots of twisties, or fast, compared to those that ride straighter roads or slower will find that they will have a higher error rate.

[Leland]

I know that when I use my Garmin Zumo in my truck it reads identical to the truck's odometer, but 5% higher than the M/C (with Speedohealer).

[V7Goose]

From my experience with GPS's and other navigation/distance measuring equipment I can tell you that the measurements on the GPS as compared the actual distance traveled on the surface may in fact be different. A GPS can not measure a curved line it can only measure a straight line. What it does is takes a reading and markes a point then it takes a second reading and makes a second mark. It than measures a straight line between those two points and that decomes the distance traveled. If you are traveling in an arc (corner) the straight line as measured between the two mark will actually cross to the inside of the arc and will show a shorter distance than what you travel in the arc. Since I do not know how to insert a drawing here you will have to do this yourself to see what I mean. First draw a circle. Then place a point at the the 10 o'clock position, this is your first "GPS point". Now place a point at the two o'clock position, this is your second "GPS point". Now draw a line between the two points, this is the "GPS distance traveled". As you can see it is shorter than if you were actual riding the circle line between the two points. If you were traveling at a higher rate of speed your points would be lets say at the 9 and 3 o'clock positions and therefore your error would be higher. How often your GPS takes a reading to set the points will affect the error rate. While this will usually be quite small it does add up. I would be willing to bet that folks that ride lots of twisties, or fast, compared to those that ride straighter roads or slower will find that they will have a higher error rate.

This statement seems to be completely accurate to me - without knowing the sample rate (how frequently does the unit store a new site fix from the satellites), I don't have any idea how to calculate the potential error, but it seems to match my experience.

 

I just got back from a 4,000 mile loop up through Ontario, Canada and back, and I took comparison GPS readings for almost every tank of gas. What I found supports the statements above - the error was different for each tank, but consistent between 3% and 4%, averaging about 3.75% more on my stock bike odometer than on my GPS. I did not really try to correlate the different errors with the specific types of roads I had been on.

 

Furthermore, while at the rally in Kitchener, Freebird and I did a little comparison between his bike (99 RSV with Vmax rear gears and speedohealer) and mine (05 RSV with completely stock drive train and speedo). Using my GPS for a 100 mile ride, his odometer read 4 miles low from GPS "actual," and mine read 4 miles high from GPS "actual." His indicated speed was dead on, showing that the Speedohealer correction was just right. My indicated speed was approximately 8% high, which is about how much he had to correct his with the Speedohealer. Note that the fact that he had different rear-end gearing is completely immaterial to this comparison, since he had CORRECTED his speedometer error with the Speedohealer.

 

So what does all this mean? It is probable that the majority of 2nd Gens are reading about 8% high for indicated speed, and about 4% high for indicated distance. If you correct your speedometer with an external device like the Speedohealer or Yellowbox, your indicated distance will then be approximately 4% lower than actual (4 miles less for every 100 miles traveled). I base my statement that this is "probable" on the same error rates I have measured on at least 5 different RSVs.

Goose

[OB-1]

...So what does all this mean? It is probable that the majority of 2nd Gens are reading about 8% high for indicated speed, and about 4% high for indicated distance. If you correct your speedometer with an external device like the Speedohealer or Yellowbox, your indicated distance will then be approximately 4% lower than actual (4 miles less for every 100 miles traveled). I base my statement that this is "probable" on the same error rates I have measured on at least 5 different RSVs.

Goose

 

My GPS-speedometer-odometer experience and numbers mirror yours. Also, the owner's manual claims that the cruise control will not engage or maintain speeds above 80mph. The GPS confirms this; however, the speedometer indicates 86mph. This leads me to believe the the errors, (indicated speed & indicated mileage), are intentional and designed into the bike.

[hillrider]

For what it's worth. My Venture (05) is off the requsite 7% per my Garmin nuvi. But the V-Star (06) is dead on. No error.

[Guest tx2sturgis]

A GPS can not measure a curved line it can only measure a straight line. What it does is takes a reading and markes a point then it takes a second reading and makes a second mark. It than measures a straight line between those two points and that decomes the distance traveled. If you are traveling in an arc (corner) the straight line as measured between the two mark will actually cross to the inside of the arc and will show a shorter distance than what you travel in the arc. ...........How often your GPS takes a reading to set the points will affect the error rate. While this will usually be quite small it does add up. I would be willing to bet that folks that ride lots of twisties, or fast, compared to those that ride straighter roads or slower will find that they will have a higher error rate.

 

Most consumer GPS units take readings once per second, or less. this is called sampling rate, or sometimes, epoch. SO...unless you are somehow traveling VERY fast around a VERY small arc, it is reading more or less, your actual traveled miles. There is some error rate in every GPS, but it is on the order of a few hundredths of a percent.

 

If what you said was actually the case, then if you left your driveway and made 4 right turns around a city residential block, then the GPS should read zero distance traveled. This isnt the case. In fact, on most GPS units, you can hold it in your hand and it will read distance and speed after you have walked even a few feet. If you walk around your driveway, hitting all four corners, it will show a distance more or less equal to what you just walked, although on car type GPS units the distance may not show up till you have walked at least a tenth of a mile.

 

Yes, there is always some error, but its reading the bikes position at least every second, and granted you may have traveled 100 feet or more in that second, but for anything we normally do on the roads, its accurate enough. You cant normally take sharp hairpin curves at 60 mph, and even if you could, you'd have to do it a LOT to make any measurable difference in total distance traveled.

 

Clear as mud?

 

[az1103]

Well, now I am really baffled! If you have a Zumo hooked up, as I do, then you know the correct speed at any time. You also know the odometer is showing the right mileage for maintenance , mpg and such.....So what would be the motivation to purchase and install something which per FQ-16 will fix one problem while creating another. You already know the info from the GPS will be better!!!! So why waste your time and money?

As to the initial question of this thread, do you realy think that the sale price will be affected more by a couple of hundred miles than by the general appearance and condition of the bike? Come on now honestly, life is too short for this.....