Confusing fuel mileage

[Cigar Mike]

Good to know that the error is <2%. I perceived it to be higher based on road signs, i.e. distance to next town, but never checked it against GPS. Thanks for posting your more scientific findings.


I think we're all on the same page. I think Mike is saying that due to odometer error, the actual MPG is not as good as the odometer would have you believe.

Sorry, I wrote that incorrectly. More miles on odometer than the GPS.

 

[dduelin]

In Florida I have to go looking for the roads with curves, otherwise many are mostly straight. Depending on road speed and how fast a GPS updates the GPS can lose distance in twisty roads as it measures time and distance between updates...anyway...it's most accurate when the roads are straighter and flatter.

I start out with the GPS and "A" trip odometer set to zero. At 10.0 miles on the GPS odometer the motorcycle odometer may be showing just short of 10.2 miles. At 30 miles on the GPS the bike may be showing 30.5 miles. Cross checking the error two or three times results in confirmation that the odometer is off about 1.8% which is in the range I have always observed. If I keep checking that same day I'll see the odometer showing 101.8 miles when the GPS turns over 100 miles.

After two years 25,xxx miles I don't do this every ride only often enough to confirm previous observations. I just installed a new type tire that I have not run before so I need to do it again to baseline the tire. Previous Metzeler Z8s and Michelin Pilot Road 3s exhibited the error range I previously posted.

It is definitely OCD behavior.

 

[itlives]

In Florida I have to go looking for the roads with curves, otherwise many are mostly straight.

I rode with a guy up a Deals Gap (slogan - 318 curves in 11 miles). He was from Florida and had a T-shirt that said
318 miles, 11 curves

 

[dduelin]

I rode with a guy up a Deals Gap (slogan - 318 curves in 11 miles). He was from Florida and had a T-shirt that said
318 miles, 11 curves

Florida has that reputation but in the north central and northern part of the state there are plenty of roads that aren't like that at all. It's almost 900 miles from one end of FL to the other and even people that live here usually know the roads only a few miles from their home.

 

[showkey]

In Florida I have to go looking for the roads with curves, otherwise many are mostly straight. Depending on road speed and how fast a GPS updates the GPS can lose distance in twisty roads as it measures time and distance between updates...anyway...it's most accurate when the roads are straighter and flatter.

I start out with the GPS and "A" trip odometer set to zero. At 10.0 miles on the GPS odometer the motorcycle odometer may be showing just short of 10.2 miles. At 30 miles on the GPS the bike may be showing 30.5 miles. Cross checking the error two or three times results in confirmation that the odometer is off about 1.8% which is in the range I have always observed. If I keep checking that same day I'll see the odometer showing 101.8 miles when the GPS turns over 100 miles.

After two years 25,xxx miles I don't do this every ride only often enough to confirm previous observations. I just installed a new type tire that I have not run before so I need to do it again to baseline the tire. Previous Metzeler Z8s and Michelin Pilot Road 3s exhibited the error range I previously posted.

It is definitely OCD behavior.

Agree ^^^^^^^^^^. GPS maps are created on a light tables using satellite photos.........someone traced those roads and In turn calculated the distances from point to point. So any given route as many point to point added calculation to reach the total............So slight errors or stacking errors will show up. Straight line airplane flight routes are easy

NAVTEC produced a video on how the maps are created...........there are or were only two or three companies producing the maps and all the GPS makes buy "similar" maps.......... But there are grade levels pay more get more detail on the roads and point of interest.