[Sean_D]

… I didn’t read that list bit carefully and was relating it more to the discussion on the other forum where people were trying to determine speedometer error percent, by comparing it with what the GPS said their speed was. Since GPS’s can have their own inaccuracies, it probably isn’t the most exact method of speed calibration.

But even relating it to Odometer. My understanding is, the Garmin Zumo 600 for example, has an accuracy of 10′. From what I understand that to mean is that is there is a circle of confusion of 10′.. more or less a 10′ bubble that the GPS has determined you are somewhere within. Granted you may be up to 10′ ahead of where it thinks you are, or 10′ behind, so it likely averages out over a long ride.

You sound like you have definitely done your homework along your route though and did a lot of double checking and fact checking, but because of that circle of confusion and other factors that can affect GPS accuracy, I think you would have to do that same homework on every route wouldn’t you?

The reason I ask is I have seen similar posts about GPS accuracy where people using them on cars, bikes, motorcycles, and marathons claim they are not always 100% accurate. The consensus, from what I can gather, is about a 2% error. I am not sure how that compares to the average error on most odometers.

I think part of the discussion on accuracy had to do with that circle of confusion and the clock rate of the unit determining how often it takes a reading. Some talk about whether GPS accurately accounts for frequent lane changes and how much those add up over a long trip, etc. I admit, I am not a statistician, and my eyes kind of glazed over after so much of it.

[SantaCruzRider]

That’s an interesting math problem. Assuming a GPS deviation of up to 10′ (which seems reasonable), your deviation for a 1 mile trip could be as much as 20′. Since there are 5,280 feet in a standard mile, that’s a possible error of as much as 0.379% (as in about one third of 1%).
That same 20′ max deviation for my 42 mile commute results in a max error of 0.009% (or less than one one-thousandth of a percent).
Technically speaking, I’d wager that we’d find more deviation error and variation based between folks you ride on the outside of turns vs inside over the course of my commute. But that would be getting pretty fussy

[Sean_D]

… folks were posting all kinds of equations that just made my head spin.

Reminds me of one I saw that had to do with determining the optimal focal length for your DSLR camera for portraiture based on sensor size. Something along the lines of … determine the length and width of the sensor. Square each number. Add the two results and then find the square root of that number. Whatever that number is double it and that will give you the correct focal length to use with your camera for portraits. Seriously? Who thinks up these things? Do they just wake bolt upright in the middle of the night with some kind of epiphany? LOL

[Rab]

I get 49/50 mpg on my mostly freeway commute. This bike uses regular (87 octane).

[Rab]

I got ~42 mpg on the recommended 89 octane on my mostly freeway commute.

I’ve read the newer fuel injected ones do a little better.

[Sean_D]

I also have a pre-EFI Bonneville and your you are pretty much spot on.

[Commonbear]

I’ve been tooling around town on a 2009 V-Star 250 and seem to average about 65 MPG, with 90% of my riding being in-city at typical speeds of 30-45 MPH. The few times I’ve taken to the highways for beach trips and such it jumps up to near 75 MPG, which makes me pretty darn happy considering that I weigh almost as much as the bike does.

[Munch]

Eddie……the V500 of yours does 80 easily…. thankfully it seems you have not laid into her yet. Mine in some situations easily got up to triple digits and held it. Granted not much above as it was unnecessary. However don’t give up on the bike, she has a lot more spunk then you think!

[Author]

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