odometer accuracy

[Black Sled]

I strapped a GPS unit on my bike first time this weekend.  Found my speedo is off almost 10% (4 - 5 mph).  I knew from reading on this board that it was off, but that is more than expected.  Anyway, has anyone checked to see if the odometer is accurate?  It seems to road milage pretty well.

Thanks,
-Ken

[MP]

The odometer is usually pretty close to correct.

MP

[GJS]

I have done the same thing. My Garmin 550 says 5-8% below my odometer.
I had read a thread suggesting that a smaller rear tire would account for this, but that does not make sense. A smaller tire should account for an increase in RPM for any given speed. The odometer runs of the front wheel on all stock Valkyries. The rear tire can't change that.

You might be on to something! Could explain why I have never gotten a ticket on my Valk.

Cheers,

Glenn

[valkmc]

Rode from Ocala to Clearwater today, we stopped and got gas and set our trip meters to zero. When we got to the hotel mine read 74 miles and my girls (Suzuki s 50) read 76. If your speedo is off so is your odometer, I would think.

[GJS]

Interesting last point.

I had always assumed the the Odometer and the Speedometer used the same cable feed. But, they have to.
That might explain the speed difference in my case. I have a smaller GoodYear Triple Tread on the back.

Maybe someone will chime in who nows the schematics.

Glenn

[Challenger]

Every vehicle I have ever put my Garmin in is off, My truck is off 3 mph at 60, the car is off 4, My buddy's Harley is off 3, the Valk is off 4. A smaller profile front tire would help, but I really don't care, Just ride and enjoy!

[Daniel Meyer]

My valk is off by 5% on the speed...but the odo is accurate. It was replaced early on in our relationship after an incident involving large balls of ice...and is the same now.

I sort of figured it's by design, as many riders I've talked to report the same on the Valk.

[John Schmidt]

The odometer and speedometer use different methods internally to get the figures you see. On everything I've read re. speedo's, without a correction device in the system you're going to have errors. However, in those same articles it always is quick to point out that the odometer is almost always spot on. Key word here...."almost."

When setting up my friends Valk with a VTX-C speedo and tach(which looks very cool and won Best in Class and Best in Show at InZane this year), I had to use a Speedo Healer to make the speedometer read correct. Since it ran off an elec. impulse like the I/S Valk, I used an I/S speedo pickup and wired the Speedo Healer into the output. I set it with about a 3mph fast "fudge factor" (he also likes to give it twist at times  ) and contacted the company about how that would affect the odometer. I was again told "not at all" because it's two different areas internally. They also told me regardless of how I set the speedometer compensation, whether it be up or down, it didn't affect the odometer readings. If the ododmeter appears to be off, it's either due to the size tire on the front or it's inherent on that particular unit. I also have found my speedo is off according to my neighbor, a local deputy, but the odometer is nearly exact.

So, just ride it and make allowances for the speedo readout. In Florida, most of the major freeways are 70mph and I know if I'm running at around 75 indicated, I'm actually only about 71-72 and have never been stopped. I've even stopped next to a trooper that I observed checking speeders and asked if he would clock me. I've never been turned down....and they also show I'm just over 3mph fast. Ride it and forget it.

[Baloo]

Same here... Zumo 550 on my 08 Jeep Wrangler is dead on with the Jeep's speedo. On my Valk, depending on the speed, the Valk speedo is about 5 mph faster than the GPS. I usually rely on the GPS for an accurate speed reading.

[Ricky-D]

I feel there can be just as much inaccuracy with a GPS units as with the speedometer. Especially so with the GPS units, if you are traveling on hilly mountainous terrain.

***

[Black Sled]

In my case I am running stock tire sizes, so that can't be the issue.  Seems to me that Honda, or any vehicle manufacturer, must insure that the Odo is pretty accurate for legal reasons.  That implies that the speedo error is by design - perhaps a means of keeping us all out of trouble?  Interesting...

[Cliff]

The speedo and odometer get their timing pulses from the same sending unit on the front wheel.  But after leaving the front wheel the signal spits into two lines- one to the speedo which uses the pulses to calculate and display the speed and the other path to a separate circuit which does the calculations for the odometer.  Being two separate circuits make it possible to have one somewhat accurate the other not.

[Daniel Meyer]

The speedo and odometer get their timing pulses from the same sending unit on the front wheel.  But after leaving the front wheel the signal spits into two lines- one to the speedo which uses the pulses to calculate and display the speed and the other path to a separate circuit which does the calculations for the odometer.  Being two separate circuits make it possible to have one somewhat accurate the other not.

Keep in mind that the standards/tourers are mechanical all the way...and have the same inaccuracy the I-states do...

Sort of supports the suspicion that it is by design...

[Jabba]

Both of mine (99 IS and a 02 Std) read about 5% faster than actual on speed and almost dead balls accurate (It's and industry term  ) on mileage best I can tell.

I read 1207 miles on the trip around lake michigan for IZ X, and my partners GPS said 1217.  That's pretty close.  Now they migh BOTH be off... but they are pretty synchronous.

 

Jabba

[BradValk48237]

MY 85 Wing was the same way, My Uncles 1500 wing, SAME..... Dads 2004 wing seems to be more accurate.....

B

[ricoman]

given that the std. speedo/odometer are mechanical (and share the same drive mechanism), I cannot see why the speedo would be off and not the odometer.
Someone 'splain how that could be. Is it internal to the guage?

[valkmc]

given that the std. speedo/odometer are mechanical (and share the same drive mechanism), I cannot see why the speedo would be off and not the odometer.
Someone 'splain how that could be. Is it internal to the guage?

I agree, my standard never has the same odometer reading as any of my friends bikes when we are on trips and fill up at the same time. I understand how the I/S could be different but how can the mechanical. If your bike shows you are going faster than the speed it seems that with the standard set up, your odometer would show you have been farther than you actually have.

[Jabba]

I thought the same thing for a while.  But even thought hey are driven from the same gear... the end device runs the input thru a different algorhythm, to get it's output.  They set up the speedo to indicate faster than actual.  even compared to mileage that's pretty close.

Thanks the lawyers.

 

Jabba

[John Schmidt]

given that the std. speedo/odometer are mechanical (and share the same drive mechanism), I cannot see why the speedo would be off and not the odometer.
Someone 'splain how that could be. Is it internal to the guage?

Fairly simple actually. The odometer is a mechanical connection, spun by the pickup cable. It's easy to make a gear setup to click over at a certain rate; i.e., every tenth of a mile, etc. since distance is a constant covered by another constant....your tire.

The cable connection for the speedometer section is not a solid hookup. That whole system operates off the principle of eddy currents created by a magnet at the top end of the pickup cable. As it spins inside an adjacent cup-like attachment, the magnetic current generated causes the second half to which your indicator needle is attached, to try and spin along with it; i.e., to catch up with the spinning magnet. It has some resistance built in with a coil spring or similar. This is to keep the needle from pegging soon as you start moving. Getting a balance of resistance to the magnetic force caused by the spinning magnet at the end of the cable is where the error factor comes in, and still being able to give you a somewhat arbitrary reading of speed that is "close enough for gov't. work....literally." That's why the odometer is usually pretty accurate....it's a direct mechanical connection, as opposed to the speedometer section which operates via an air gap with the magnetic current flowing through it.

Electronic speedos are a bit different, using elec. pulses as in the I/S system. The internal electronic circuitry counts how quickly the pulses arrive and convert that into a speed reading as a figure on an LCD dashboard. If the speedo is electric but has a needle, the circuitry drives a small motor(stepper motor) that controls the needle display.

[Mr. Nuts]

Like others my speedo is about 3-4 mph fast at 75 but my odometer is almost correct (very slightly low). I have verified this extensively with mile markers here in Montana and I also run a Sigma 1609 bike computer that is calibrated very accurately by wheel size. If you want exceptional accuracy the Sigma delivers for about $30 on ebay. Mine also has a couple of trip meters, clock, temperature, highest speed, and average speed and a backlight. Its easy to setup and use. Best I see on ebay is $29.35 buy it now with $2.66 shipping so it is cheap fun!

http://www.sigmasport.com/us/produkte/bikecomputer/topline_2009_wired/bc1609/?punkt=features

[Cliff]

The speedo and odometer get their timing pulses from the same sending unit on the front wheel.  But after leaving the front wheel the signal spits into two lines- one to the speedo which uses the pulses to calculate and display the speed and the other path to a separate circuit which does the calculations for the odometer.  Being two separate circuits make it possible to have one somewhat accurate the other not.

Keep in mind that the standards/tourers are mechanical all the way...and have the same inaccuracy the I-states do...

Sort of supports the suspicion that it is by design...

ooops, My mistake,,, should have specified I was describing the I/S setup  

[MP]

The gov't mandates that speedos not read low.  They must read right, or a little fast.  It cannot read low.  So, they make them read a little high, to make sure that if a tire is changed or something, they do not read low.

MP

[valkmc]

The odometer and speedometer use different methods internally to get the figures you see. On everything I've read re. speedo's, without a correction device in the system you're going to have errors. However, in those same articles it always is quick to point out that the odometer is almost always spot on. Key word here...."almost."

When setting up my friends Valk with a VTX-C speedo and tach(which looks very cool and won Best in Class and Best in Show at InZane this year), I had to use a Speedo Healer to make the speedometer read correct. Since it ran off an elec. impulse like the I/S Valk, I used an I/S speedo pickup and wired the Speedo Healer into the output. I set it with about a 3mph fast "fudge factor" (he also likes to give it twist at times  ) and contacted the company about how that would affect the odometer. I was again told "not at all" because it's two different areas internally. They also told me regardless of how I set the speedometer compensation, whether it be up or down, it didn't affect the odometer readings. If the ododmeter appears to be off, it's either due to the size tire on the front or it's inherent on that particular unit. I also have found my speedo is off according to my neighbor, a local deputy, but the odometer is nearly exact.

So, just ride it and make allowances for the speedo readout. In Florida, most of the major freeways are 70mph and I know if I'm running at around 75 indicated, I'm actually only about 71-72 and have never been stopped. I've even stopped next to a trooper that I observed checking speeders and asked if he would clock me. I've never been turned down....and they also show I'm just over 3mph fast. Ride it and forget it.

Good points, but just to try it, today I rode home from Clearwater with four bikes, 5 including my valk. We all filled up and set our odometers to zero, took one short side trip and stopped in Ocala just before we broke up. Not one of the odometer readings was the same. My Valk read 109.6, another bike read 110.7, the lowest reading was 108.2. Not huge differences but I tend to think our odometers are about as accurate as our speedometers. My math may not be perfect but if my odometer is off 1 mile in 100 miles, than the 70,000 odometer reading I have could be off by 700 miles. Doesn't matter really as I will never part with the Valk no matter what else I buy so mileage is no issue.