Odometer Calibration

[Fred W]

Hey! How good an assumption is it that the mile markers are actually correct?

If you are talking about the regular ones, not very close. But over a long distance (100 miles) they should be pretty good. The "measured mile" markers are very close. Those are specifically measured and installed to allow you to check your odo and speedo. Maybe they are just an East Coast phenomenon?

 

[old&slow]

Well Dan, for me it's my day off. Only get one a week this time of year so I'll be out and riding in about a hour (when temps reach 50).As for strange things happening to the mind well....

Old land surveyors are notorious drunks and drug users and both have been linked to the mind and strange things. :blink:

33 degrees here ,, spitting snow ,,,poured down rain yesterday ,,, probably get back up to 50 ,,, in April or May ...

until then a glass of Wild Turkey or Maker's Mark ,,, get the maps out and think about spring,,,

 

[El Toro]

Hey! How good an assumption is it that the mile markers are actually correct?

If you are talking about the regular ones, not very close. But over a long distance (100 miles) they should be pretty good. The "measured mile" markers are very close. Those are specifically measured and installed to allow you to check your odo and speedo. Maybe they are just an East Coast phenomenon?

Measured miles show up on roads at least as far inland as Tennessee. There are a few here and there.

It is not uncommon in urban areas to have regular mile markers every tenth of a mile out here. 24.1, 24.2, 24.3, etc.

My experience is that most of the time the mile markers on our interstates are pretty close to right, but it is good to run longer segments, like 10 miles, or 100 miles. A 100 mile run with odometer, GPS, and mile markers will usually give you three different numbers, but in my experience they're separated by less than 2 miles with most vehicles.

 

[dsmack]

Hey! How good an assumption is it that the mile markers are actually correct?

If you are talking about the regular ones, not very close. But over a long distance (100 miles) they should be pretty good. The "measured mile" markers are very close. Those are specifically measured and installed to allow you to check your odo and speedo. Maybe they are just an East Coast phenomenon?

Nope, they're placed here on the West Coast as well. As for accuracy, I can only speak to those here in WA State... I know that the WSDOT guys use a calibrated measurement to place the signs with high accuracy, and the run always seems to be for 5 miles so the length is sufficient for a decent test.

The typical "Mile Marker" signs you see on the little sight post markers on the shoulder are considerably less accurate in many cases. They are located too close to the road right-of-way and are oftern wiped out by passing motorists. The crew who replaces the missing signs and sight posts do not use any sort of calibrated measurements... just hammer another one in the ground.

The only state I am aware of here on the West Coast that does not use mile marker signs is California. They have always resisted for some reason the whole concept of identifying mile posts and exits by a logical system of numbering like the rest of the states use... go figure!

I'm bored today - 38 degrees, pea-soup fog... couldn't see a mile post marker at twenty five feet.... sigh.

Be safe out there!

Don

 

[Warchild]

I'm bored today - 38 degrees, pea-soup fog... couldn't see a mile post marker at twenty five feet.... sigh.

Only marginally better here in the Tri-Cities to the southwest of you.... 41 degrees, inversion layer is slightly aloft to enable okay driving...

I am still the only bike in the parking lot at work. Again.

 

[dsmack]

Yep, the forcast for the next couple of days doesn't look promising... more of the same on tap with the inversion. It has raised enough here now to encourage me to get my fat ass moving and take the bikes over to the local stop n rob to top off the tanks with fresh gas/stabilizer for the winter. Damn, I hate winter!

At least with the gas in the system treated, and a 2.5Gal can of treated gas in the garage for top-offs after riding, I can look forward to sneaking in a few days of riding a bit during the "Black Days of Winter". I can recall a few years ago when I was still a skier, that I used to actually look forward to snow. Those days are certainly gone!

Be Safe!

Don

 

[Geezer]

It was 40 F and sunny here this morning. I was getting ready to use up a gallon or two of gas over lunch, but it started to rain hard before I could free up and get out. I haven't given in and winterized yet, but it will be soon.

 

[dsmack]

Ironically, just after I posted the above, the fog burned off and it warmed up a couple of degrees to around 40 - 42. Because I just put in some stabilizer for the gas and keep a Battery Tender hooked up, I can be ready to roll with a simple tire pressure check and unplugging the battery tender.

That's exactly what I did just an hour and a half ago... my God it feels good to get something exciting between my legs! :wub:

The fog has since returned... back to your regularly scheduled programming.

Ride safe!

Don

 

[Fred W]

Ironically, just after I posted the above, the fog burned off and it warmed up a couple of degrees to around 40 - 42. Because I just put in some stabilizer for the gas and keep a Battery Tender hooked up, I can be ready to roll with a simple tire pressure check and unplugging the battery tender.
That's exactly what I did just an hour and a half ago... my God it feels good to get something exciting between my legs! :wub:

The fog has since returned... back to your regularly scheduled programming.

Ride safe!

Don

I don't mind the fog until it starts to collect on the ground. :blink:

Once the fog starts to pile up, it gets to be rough going...

 

[El Toro]

There were a couple of inches of "fog" on the cars coming down from the top of the Cumberland Plateau this morning. School was cancelled far and wide. I grew up in the Northeast, so the Southern reaction to "fog" is pretty entertaining.

 

[Tolstoy]

Tolstoy - a 1.5% odo inaccuracy is quite typical... I think you are good-to-go as you are now. If this error really irritates you, consider installing a Speed-O-Healer v. 4.0. This component allows you to calibrate your speedometer *or* odometer to virtually 100% dead-nuts accuracy.
Mind you, the Speed-O-Healer is both mutually exclusive and mutually sympathetic.

Mutually exclusive: you can accurately calibrate the speedo OR the odo... not both.

Mutually sympathetic: if re-calibrating the speedometer, the odometer will become less accurate; if re-calibrating the odometer, the speedometer will become less accurate.

Thanks, Warchild. I'm not at all irritated by a +1.5% odo inaccuracy. I was concerned by the +20% error I was seeing, when comparing to the mileposts. If my odo was adding 20%, I was averaging 48 mpg. If my odo was dead accurate, I was averaging only 40 mpg. 6 gallons x 48 mpg = 288 miles. But 6 gallons x 40 mpg = only 240 miles. I think it was worthwhile for me to try to resolve the discrepancy, so I don't overestimate my range and risk running out of gas in the desert.

I've been criticized for using a Rolatape because of innacuracies that may be caused by temperature variations and road-surface irregularities. I've used a Rolatape for countless traffic accident investigations and reconstructions. I've successfully defended my measurements in court, so have reasonable confidence in them. I'm aware of the precautions to take when using a Rolatape. The road surface was new, smooth and clean asphalt. I walked very slowly, to minimize, or eliminate as much as possible, any "skipping" of the wheel. I checked the Rolatape against two other measuring devices and found it to exactly agree with them. "Old school", I agree, but I wonder if the GPS advocates can vouch for having done as much due diligence to check their accuracy.

If any GPS-owner in my area (southeastern Arizona) would like to show me the error of my old-fashioned ways, I'm certainly willing to be re-educated.

Thanks, everyone, for sharing your thoughts and offering your opinion.

 

[bramfrank]

Note that odometer error changes with tire wear and pressure on top of everything else - and that measured miles are only as accurate as the driver - assuming the markers are properly placed - wandering about the lane will add somewhat to the distance travelled.

GPS is NOT an accurate mechanism for measuring accumulated distance, though it IS accurate for measuring instantaneous speed, once per second.

 

[Tolstoy]

Note that odometer error changes with tire wear and pressure on top of everything else - and that measured miles are only as accurate as the driver - assuming the markers are properly placed - wandering about the lane will add somewhat to the distance travelled.
GPS is NOT an accurate mechanism for measuring accumulated distance, though it IS accurate for measuring instantaneous speed, once per second.

Thanks. I've only recently learned what a GPS is, and from the little reading I've done, it appears that they're only accurate to within a couple of meters. My old-fashioned measuring device and procedure are better than that. I experimented with speed/distance calculations while attending the Traffic Institute at Northwestern University, and found that tire tread wear and tire pressure (within safe parameters) had an insignificant affect. By "insignificant" I mean for the purposes of traffic accident reconstruction and speed enforcement.

For calibrating my speedometer, I'm going to ask a local PD motorcycle officer to radar me. I suppose the forum will lecture me now, about the inaccuracy of radar guns and the untrustworthiness of polce officers.

 

[Fred W]

The only problem I see with your odometer calibration technique has nothing to do with your rollatape measurement device (not really even sure what that is). But let's assume that you accurately measured the 1/10th mile course. By only checking your odometer over a 1/10th mile, which is essentially a single division on the odometer, the gauge R&R (repeatability and reproduceability) of the odometer is not adequate to get a significant individual reading. To improve the significance, you would have to repeat the experiment many times and then make an analysis of those results as a group. Only then could you apply some calculations to your 1/10th mile data and determine if there is any significance of the results.

If you made the same experiment over 1 mile, 10 miles or 100 miles, since the R&R of the odometer is always roughly uniform, you would find the significance improves at increasing mileages (to a point of diminishing returns).

Same principle would apply to the highway mile markers along the side of the road. The distance between the individual 1/10th mile markers is variable as they tend to place them wherever a convenient spot is. But the absolute accuracy of sign placement becomes less and less significant as the total distance is increased. In other words, even though the first sign you pass may be off by say 20 feet (somewhat significant in a 1 mile measurement), the 100th mile post is also only likely to be off by the same amount. That 20 foot error would be is insignificant over 100 miles.

A GPS'es inherent inaccuracy should be a similar situation. A GPS may only be able to accurately locate you to within 3-5 meters absolute position (1-3m with WAAS), and that would significantly effect your distance/speed calculation over 1/10th of a mile, the GPS will be accurate to within the same 3-5 meters absolute position at the end of a 100 mile trip that is was at the beginning.

I won't get into doppler radars as that could become political.

 

[ionbeam]

Go to:

Speedo Healer



Buy their FJR1300 calibrator and get on with your life.

:lol:

 

[luvtoride]

This is a completely different kind of anal than the anal that I'm used to.

What difference does being a tad more accurate make, anyhow?

 

[Ignacio]

GPS is NOT an accurate mechanism for measuring accumulated distance, though it IS accurate for measuring instantaneous speed, once per second.

And how did you arrive at that conclusion?

GPS can be a very accurate mechanism for measuring accumulated distance.

The critical nature being in areas with clear and continuous visibility to multiple satellites. Would I expect to measure distances in downtown Chicago or the twisties and canopy of the forest......no as drop is going to be a problem. If I'm wandering the wide open vistas of Eastern Montana where you can rack up significant digits with a continuous signal....nuts on.

What difference does being a tad more accurate make, anyhow?

I don't much care about the MPG aspect of things, but accurate odometer readings are important to those LD folks in rallies. Both to establish minimum miles and perhaps by the rallymaster to audit miles. There's always a calibration run before each rally and typically validation is done by several different riders using GPS.

 

[ionbeam]

....What difference does being a tad more accurate make, anyhow?

Each time I get on my FJR I know in my heart that the odometer is wrong. That feeling is always there, it's like a burning coal eating away at my soul, I know that my mileage is wrong. The error is a wearing burden, dragging me down, holding me back, making me tired and unable to face the heavy weight of knowing that I'm not like the others. It haunts me, I can't eat, I lay awake at night with the grinding awareness that I'll never know how far I've traveled and even worse -- not knowing how far I may yet safely go. Oh but it is darkening my heart, it leaves me emotionally deflated, I'm unclean. I don't know if I can carry this encumberment another day. The despair makes me want to bring it to and end and stop the pain, the humiliation, and the soul destroying blackness of this unrelenting inaccuracy.

:lol: :lol: :lol: :lol: :lol: :lol:

I'm not at all irritated by a +1.5% odo inaccuracy. I was concerned by the +20% error I was seeing, when comparing to the mileposts. If my odo was adding 20%, I was averaging 48 mpg. If my odo was dead accurate, I was averaging only 40 mpg. 6 gallons x 48 mpg = 288 miles. But 6 gallons x 40 mpg = only 240 miles. I think it was worthwhile for me to try to resolve the discrepancy, so I don't overestimate my range and risk running out of gas in the desert.

See post #34.

 

[Fred W]

Note that odometer error changes with tire wear and pressure on top of everything else - and that measured miles are only as accurate as the driver - assuming the markers are properly placed - wandering about the lane will add somewhat to the distance travelled.
GPS is NOT an accurate mechanism for measuring accumulated distance, though it IS accurate for measuring instantaneous speed, once per second.

Ummm, I think you may have that bass ackwards.

 

[Fred W]

This is a completely different kind of anal than the anal that I'm used to.
What difference does being a tad more accurate make, anyhow?

Makes no difference at all to me. But, geeze... don't you like to play Trivial Pursuit?