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[BigLew55]

I noticed my speedo was off 4 MPH. I used the GPS to prove the speed was off. I also noticed that when sitting still the speedo was sitting at 4MPH! The dealer replaced the speedo and it now matches the GPS perfectly at all speeds! Let the dealer replace the speedo and you will probably be good to go.

The (onboard) GPS matching the speedo doesn't make either one right.  IF the GPS is getting it's info from the same place the speedo is, then they're both wrong now.

We're trying to establish the IF.  Does the speedo signal also drive the (onboard) GPS display.

I believe this is true only from what I've read.  Also, I consider the alternative.  Would HD put an accurate GPS speedo display in close proximity to it's speedometer when they're historically so far off?

Until I get me a 2015, I won't know for sure. 

[grc]

The (onboard) GPS matching the speedo doesn't make either one right.  IF the GPS is getting it's info from the same place the speedo is, then they're both wrong now.

We're trying to establish the IF.  Does the speedo signal also drive the (onboard) GPS display.

I believe this is true only from what I've read.  Also, I consider the alternative.  Would HD put an accurate GPS speedo display in close proximity to it's speedometer when they're historically so far off?

Until I get me a 2015, I won't know for sure.

I agree Lew.  While it would seem to make sense to use satellite data to calculate true speed, just like the portable GPS units do, I can also see Harley opting to just use the speed generated by the speed sensor on the bike.  As you noted, why give customers ammunition to use against you by showing the true speed right next to the inflated inaccurate reading from their historically poor speedometer?

As for RonandJanet's situation, that was a different set of circumstances from what most everyone is experiencing.  The needle on the speedo was mispositioned so it would never read what the onboard sensor determined the speed was, while the digital reading on the infotainment screen would.  Now that the analog speedo is reading the same as the built in GPS, I wouldn't take that to mean either is accurate.  If it were me I would borrow a stand-alone GPS and use it to check for true speed.

Jerry

[BigLew55]

I agree Lew.  While it would seem to make sense to use satellite data to calculate true speed, just like the portable GPS units do, I can also see Harley opting to just use the speed generated by the speed sensor on the bike.  As you noted, why give customers ammunition to use against you by showing the true speed right next to the inflated inaccurate reading from their historically poor speedometer?

As for RonandJanet's situation, that was a different set of circumstances from what most everyone is experiencing.  The needle on the speedo was mispositioned so it would never read what the onboard sensor determined the speed was, while the digital reading on the infotainment screen would.  Now that the analog speedo is reading the same as the built in GPS, I wouldn't take that to mean either is accurate.  If it were me I would borrow a stand-alone GPS and use it to check for true speed.

Jerry

Absolutely.   

I already intend to arrange my next ride with the onboard GPS and my z660, using the pigtail and it should work pretty well from initial reports. 

I will probably re-calibrate the speedo with a PV or TTS as well.  I finally did that with my most recent ride, and it is so nice to know how fast you're actually going.

[dkl032]

i am off the same 3-4 mph.  gps and speedo are not same on my bike.  gps is satellite driven (or at least should be).

[BigLew55]

i am off the same 3-4 mph.  gps and speedo are not same on my bike.  gps is satellite driven (or at least should be).

I wonder if it's configurable, somehow, to choose whether it's satellite or ECU driven?

That would be a stretch, in my opinion, for HD to include that...

[grc]

i am off the same 3-4 mph.  gps and speedo are not same on my bike.  gps is satellite driven (or at least should be).

Take a look at the posts by RonandJanet, that bike had an obviously defective speedometer and it also didn't match the built-in GPS.  Yours may be the same situation.

I think at this point I'd not trust either the speedometer or the built-in GPS, but would instead have the speed checked with a stand-alone GPS or on a calibrated dyno.  Harley quality is much too variable (nonexistent in my opinion) to trust.

Jerry

[grc]

I just thought I'd add a side note to this speedo conversation to make sure everyone knows that as they ride and wear rubber off the rear tire, the problem will become worse.  Using the dimensions of the current 180/65 x 16  rear tire on the FLHTKSE as an example, the new tire starts out with an outer diameter of 25.33" and a tread depth of 10/32 (0.31)".  If you run the tire until the tread depth is 1/32 (0.031)", the outer diameter will have been reduced by 18/32 (0.56)".  This means that for each revolution of the wheel the bike will actually travel a shorter distance on the road, and since the speed sensor is measuring rotations and not actual distance the speedometer error will get worse.  In this example, the difference from brand new tire to worn out tire would be 2.3%.  At 70 mph actual, that error would result in a speedo reading of 71.6 mph.  Add that to the 4 mph error already built into the average bikes speedometer, and the total error approaches 6 mph.

Since very few of the folks on this site seem to worry all that much about staying below the speed limits (at least based on what I read around here from people claiming to cruise at 80 and up), all this error is really just Harley's way of trying to keep it's customers out of jail.  So quit complaining about the highly inaccurate speedometers on a Harley, and send them a nice thank you note instead.

Jerry

[HarleyJeffOregon]

Every Harley I have had is off 4 mph also. I just look at my gps.

[mamacdonald]

I ride a 2012 cvo ultra and the wife rides a 2012 triglide.  Last year we took a 3800 mile ride out west and her trike recorded 80 less miles than my bike.  My buddy was also with us on his 2011 roadglide and his mileage was the same as mine.    I was thinking that her trike speedo was off...idk

[CVOjunkie]

first off toss the sert and get a tts and when u do mods dyno it and get the speedo reset mine was off at 75 about 6 miles per hour

[RonandJanet]

I plan to use my Garmin GPS and match to the CVO on-board GPS. I am guessing (not researched) that the on-board GPS is working just like a regular GPS and using the satellite for positioning and speed. Since it is based on Garmin it makes sense. I hope to get this done soon!

[LARK]

I just thought I'd add a side note to this speedo conversation to make sure everyone knows that as they ride and wear rubber off the rear tire, the problem will become worse.  Using the dimensions of the current 180/65 x 16  rear tire on the FLHTKSE as an example, the new tire starts out with an outer diameter of 25.33" and a tread depth of 10/32 (0.31)".  If you run the tire until the tread depth is 1/32 (0.031)", the outer diameter will have been reduced by 18/32 (0.56)".  This means that for each revolution of the wheel the bike will actually travel a shorter distance on the road, and since the speed sensor is measuring rotations and not actual distance the speedometer error will get worse.  In this example, the difference from brand new tire to worn out tire would be 2.3%.  At 70 mph actual, that error would result in a speedo reading of 71.6 mph.  Add that to the 4 mph error already built into the average bikes speedometer, and the total error approaches 6 mph.

Since very few of the folks on this site seem to worry all that much about staying below the speed limits (at least based on what I read around here from people claiming to cruise at 80 and up), all this error is really just Harley's way of trying to keep it's customers out of jail.  So quit complaining about the highly inaccurate speedometers on a Harley, and send them a nice thank you note instead.

Jerry

I was wondering when someone would go to the effort to calculate tire wear and it's effect on speedo accuracy. Well done. I'm about 1.5 to 2 mph fast at 70 mph and the rear tires is just about ready to replace.

[phato1]

I just thought I'd add a side note to this speedo conversation to make sure everyone knows that as they ride and wear rubber off the rear tire, the problem will become worse.  Using the dimensions of the current 180/65 x 16  rear tire on the FLHTKSE as an example, the new tire starts out with an outer diameter of 25.33" and a tread depth of 10/32 (0.31)".  If you run the tire until the tread depth is 1/32 (0.031)", the outer diameter will have been reduced by 18/32 (0.56)".  This means that for each revolution of the wheel the bike will actually travel a shorter distance on the road, and since the speed sensor is measuring rotations and not actual distance the speedometer error will get worse.  In this example, the difference from brand new tire to worn out tire would be 2.3%.  At 70 mph actual, that error would result in a speedo reading of 71.6 mph.  Add that to the 4 mph error already built into the average bikes speedometer, and the total error approaches 6 mph.

Since very few of the folks on this site seem to worry all that much about staying below the speed limits (at least based on what I read around here from people claiming to cruise at 80 and up), all this error is really just Harley's way of trying to keep it's customers out of jail.  So quit complaining about the highly inaccurate speedometers on a Harley, and send them a nice thank you note instead.

Jerry

Your right, and therefore a nice card will be sent to HD thanking them for saving me all that money I would've spent on traffic fines 

[BigLew55]

Plot Twist!

I bought a 2015 FLHTK a few weeks ago, and I finally got around to checking how far off the speedo is.  Using a reliable app on my phone with gps, and comparing it to the bike speedo, and the speed displayed on the built in gps ,there was no disparity.

I had to check it again a few minutes later.

I've had gps on my last 4 bikes (03 04 09 11, all touring) and they have been consistently 4-7 percent wrong. 

Today, I was pleasantly surprised.  I know my buddy's street glide was wrong before I dialed it in with a power vision.

Any other 2015 owners have any feedback for this? Did hd finally address it?

[skratch]

I just thought I'd add a side note to this speedo conversation to make sure everyone knows that as they ride and wear rubber off the rear tire, the problem will become worse.  Using the dimensions of the current 180/65 x 16  rear tire on the FLHTKSE as an example, the new tire starts out with an outer diameter of 25.33" and a tread depth of 10/32 (0.31)".  If you run the tire until the tread depth is 1/32 (0.031)", the outer diameter will have been reduced by 18/32 (0.56)".  This means that for each revolution of the wheel the bike will actually travel a shorter distance on the road, and since the speed sensor is measuring rotations and not actual distance the speedometer error will get worse.  In this example, the difference from brand new tire to worn out tire would be 2.3%.  At 70 mph actual, that error would result in a speedo reading of 71.6 mph.  Add that to the 4 mph error already built into the average bikes speedometer, and the total error approaches 6 mph.

just went on a roadtrip to galveston this past week.  my tires have a little over 9k on them (reference point for wear), and comparing my portable gps to the bike's speedo, my bike reads 2 mph faster at 70mph.  so with brand new tires, i think that my speedo is going to be pretty accurate.  knock on wood.