Speedometer Error on my '23 RT

[Motor32]

I just returned from a ride with my phone speedometer app running on my '23 RT.

 

 Speedometer App speed indicated = 50 MPH  /  TFT = 53MPH

                                                                   60 MPH  /  TFT = 63MPH

                                                                   70 MPH  /  TFT = 73MPH

                                                                   80 MPH  /  TFT = 83MPH

I was consistently 3 MPH below what BMW had programmed into the TFT speed, FYI. (your results may vary, lol)

 

Steve

 

App I use :

 

 

[Skywagon]

Been that way for 20 or more years...unless you ride a pd bike which are accurate.

[Motor32]

Right, they've had it this way on all of my bikes over the years. One bike I had was 7 MPH over, crazy.

 

Steve

[dirtrider]

43 minutes ago, Motor32 said:

I just returned from a ride with my phone speedometer app running on my '23 RT.

 

 Speedometer App speed indicated = 50 MPH  /  TFT = 53MPH

                                                                   60 MPH  /  TFT = 63MPH

                                                                   70 MPH  /  TFT = 73MPH

                                                                   80 MPH  /  TFT = 83MPH

I was consistently 3 MPH below what BMW had programmed into the TFT speed, FYI. (your results may vary, lol)

 

Steve

 

App I use :

 

 

Evening Motor32

 

That is actually fairly accurate for a Civilian BMW motorcycle. Even a BMW police motorcycle might not be that accurate unless it has police specification tires on it.

 

BMW can not have a speedometer reading slower than the motorcycle is traveling even with  different tire brands, or especially with new or worn tires. 

 

How many miles on your tires? As the speed (indicated) vs (actual)  gets worse as the tires wear.

 

 

[Dave_in_TX]

57 minutes ago, Motor32 said:

I just returned from a ride with my phone speedometer app running on my '23 RT.

 

 Speedometer App speed indicated = 50 MPH  /  TFT = 53MPH

                                                                   60 MPH  /  TFT = 63MPH

                                                                   70 MPH  /  TFT = 73MPH

                                                                   80 MPH  /  TFT = 83MPH

I was consistently 3 MPH below what BMW had programmed into the TFT speed, FYI. (your results may vary, lol)

 

Steve

 

App I use :

 

I see about the same difference between my GPS and the displayed speed on my 2020 GS.

 

[Motor32]

10 minutes ago, dirtrider said:

Evening Motor32

 

That is actually fairly accurate for a Civilian BMW motorcycle. Even a BMW police motorcycle might not be that accurate unless it has police specification tires on it.

 

BMW can not have a speedometer reading slower than the motorcycle is traveling even with  different tire brands, or especially with new or worn tires. 

 

How many miles on your tires? As the speed (indicated) vs (actual)  gets worse as the tires wear.

 

 

Mine are new, with only 600 miles.

 

Steve

[Hosstage]

That's pretty common with cars and trucks too. It's a lawsuit issue with speeding citations. Can't have the Speedo read lower than actual, ever, so they err on the high side.

[Motor32]

6 minutes ago, Hosstage said:

That's pretty common with cars and trucks too. It's a lawsuit issue with speeding citations. Can't have the Speedo read lower than actual, ever, so they err on the high side.

Yes, the "Nanny" state.

 

Steve

[RandyShields]

On the ride back to NC from the MOA rally in Springfield MO, I asked the initial leader (on a "21 or '22 RT) why we were riding so slow.  He was riding at his speedo indicated 71-72 mph in a 65 mph zone.  He didn't realize (until I told him, based on my GPS) that his actual speed was 63-64 mph.  As it was hard for to wrap his head around such a large discrepancy and lead at a speedo indicated 78 mph, I took over lead duty.

[9Mary7]

IIRC.....NHTSA allows up to ten percent optimism (high read error) from the factory.

I guess they had to put a limit to how many warranty miles you're being cheated out of! 

Though I did see someone use the 10% error as a speeding defense in court once......

[Skywagon]

41 minutes ago, 9Mary7 said:

speeding defense in court once

Did it work?

[dirtrider]

1 hour ago, 9Mary7 said:

IIRC.....NHTSA allows up to ten percent optimism (high read error) from the factory.

I guess they had to put a limit to how many warranty miles you're being cheated out of! 

Though I did see someone use the 10% error as a speeding defense in court once......

Morning 9Mary7

 

That used to be the case for automobiles with mechanical speedometers (trucks were different) & I was never sure where motorcycles fit in. Electrical (electronic) speedometers can have a tighter tolerance with a different +/- factor (last I knew it was +/- 2.5% @ 50 or 60 mph I believe, but that was during the experimental era just after electronic speedometers went main stream & auto manufactures were given some time & leeway to experiment with the accuracy window.  (it can be much tighter & more accurate using electronic speedometers, especially if they use the combined input of all 4 wheels from the ABS wheel speed sensors)

 

I haven't done any automotive OEM speedometer calibration certification since the electronic speedometer era so I can't say what the current automotive spec is.  

 

Again I'm not even sure where motorcycles fit in as they are single track vehicles with rounded profile tires so they can very the indicated speed as the motorcycle is leaned over onto the smaller diameter part of the tire as well as have different tire options.   

 

When it comes to BMW motorcycles I'm guessing  their  main speedometer accuracy certification is based on the  ECE Regulation No. 39, stating that a speedometer can read high by as much as 10 percent plus 4 km/h at a specified speed, but under no circumstances can the speedometer read low. Then as long as that fits (& stays) within the USA standards they just import it that way.

 

On my modern motorcycles I typically use a GPS as that is way more accurate than the factory speedometer as long as I am on straight road that is fairly flat. A GPS does truncate it's calculation points so with a lot of long curves in a section it can lie to you a little but not a lot. 

 

On my older motorcycles (before GPS) I made up a sticker that showed the indicated vs actual speed so I had some idea on how fast I was ACTUALLY traveling. We used to do the same with all our test vehicles where I work (that is where I got used to using the indicated vs actual stickers to be precise)

 

[Motor32]

This must have been a fluke that the speedometer (76 MPH), Nav5, and the App all read almost the same 75 MPH on my 2020 RT.

Steve

 

[9Mary7]

2 hours ago, Skywagon said:

Did it work?

No, the guy was doing 35 in a 25 school zone, passing 25mph traffic.

Also had a guy speeding on an Airhead at 20 over on a 45mph street tell the judge (pompously stated) that as a BMW rider, "they don't travel at unsafe speeds and have the best safety record of motorcyclists"...(college professor). So the judge found him guilty......... 

[9Mary7]

1 hour ago, dirtrider said:

within the USA standards

I couldn't find the section I referenced since I don't need it anymore, however current my experience has been that the digital ones are usually spot on or less than 2% off and never read low (with stock tires/gearing). Even my 1989 260E was analog and spot on. 

[realshelby]

I think the RT speedometer readout can be accurate....if you link it to your NAV 5 or 6 GPS unit. Not sure what years, but my 14 is that way as I recall. 

[Rob Nowell]

3 hours ago, 9Mary7 said:

the judge found him guilty.......

...guilty of being a knucklehead!

[Randyjaco]

It also helps cover up poor miles per gallon figures 

[9Mary7]

6 hours ago, Rob Nowell said:

guilty of being a knucklehead

Knucklehead on an Airhead!!    

[Paul De]

My '99 Oilhead was about 10% optimistic at highway speed.  It cost me $166 to have an accurate speedometer pace me and provide me with  a receipt to be able to calculate that. On '15 Wethead I figured it is about 5% optimistic compared to what the Nav V indicates, which at the price of the Nav unit the previous method to calculate the discrepancy was cheaper   Anyway I was happy to see that BMW made an improvement as 10% is kind of an embarrassing level of error on a premium priced motorcycle.   Either way when touring around the level of plus error is easy to deal with and when riding frisky the error is nearly meaningless I almost never look at the speedo as I'm too focused on picking lines and braking points