TFT Speedo Accuracy

[RPG]

Silly question, but still wanted to ask if the new RT's with the TFT display have an accurate speedometer?

 

Thanks,

 

RPG

[dirtrider]

1 hour ago, RPG said:

Silly question, but still wanted to ask if the new RT's with the TFT display have an accurate speedometer?

 

Thanks,

 

RPG

Afternoon Rick

 

I can't speak to ALL but the few I have ridden are within a couple of miles an hour of the GPS.  But the ones I have ridden had fairly new tires (makes a slight difference)

 

 

 

[Hati]

1 hour ago, RPG said:

the new RT's with the TFT display have an accurate speedometer?

 

 

No. It's out twice as much as my '13 cam-head R. The RT is out by about 6 to 8 km/h opposed to the R's 3.

 

Most countries have design rules that mandate speedos to be optimistic not accurate. 

[bimmers]

I have compared my 21 RT to a phone installed GPS speedo app. It was spot on. Same goes for the cars GPS based speedo while the "mechanical" one is off some.

I was also told in Europe that cars speedos are supposed to be Ab 4km/h optimistic at 100 and when testing a VW Golf that is what it was. 

The bike speedo has also recently been showing same as some road speed signs, which I realize are off most of the time. 

 

So in short I think it is close enough to assume it is just a little optimistic.............

 

H

[EdM]

Mine appears to be about 2% higher than actual based on the odometer which clocked 5.1kms in a 5km marked test zone.

[Mellow]

Mine is 4-5 mph fast.  Drives me crazy-er lol... My previous Tracer 900 was 1 mph off most of the time.. I tend to look at the zumo xt most of the time but still do the mental calculations... guess it keeps my mind alert lol.. I wish there was a way to calibrate it.

[dirtrider]

17 hours ago, RPG said:

Silly question, but still wanted to ask if the new RT's with the TFT display have an accurate speedometer?

 

Morning Rick

 

There are some USA & some European  (or non USA anyhow) comments in this thread.  Keep in mind that USA standards are different than European with the UK standards allowing the most deviation (at least that I know of). I really don't know how motorcycle speedometers readings are governed as unlike automobiles the wheel rotating speeds change as the motorcycle tire diameter changes as the motorcycle is leaned over.  

 

Also, keep in mind that since the Honda odometer law suit, odometers (at least in the USA),  are held to a tighter tolerance than the actual speedometers.  

[RPG]

Thank You all for your comments. Why  I asked was centered around if the new TFT display gets its speedo reading from a GPS, or from the bike itself.

 

Rick

[Paul De]

Spedos always seem optimistic on BMW motorcycles.  My Oilhead was the worst at about 10% optimistic.  My Wethead is better at about 5%. Sorry, the wife would kill me if I upgraded to the Shifcam, so no data point there.  Most of my HD riding friends have spedos that were all were pretty close to spot on.  Go figure. It must be a corporate thing on how accurate they want the speedo within the regulations, with an obvious marketing motivation to make them optimistic.  My internal land speed sensor works best though.  If my eyes are bugging out it means the entry speed to the corner was too high

[strataj]

1 hour ago, RPG said:

Thank You all for your comments. Why  I asked was centered around if the new TFT display gets its speedo reading from a GPS, or from the bike itself.

 

Rick

The TFT on my 02R1250RT doesn't get any info from the GPS only displays map/directions.  I wish it got the time like like on my wethead form the Nav, it was nice not to have to manually change when time changes (standard/DST) and it displayed the correct time for your location, changed on the fly when you crossed time zones.

[Hosstage]

GPS based speedo on the TFT would be bad if service is lost, speedo is lost, and a speeding citation issued. Big lawsuit.

2 hours ago, RPG said:

Thank You all for your comments. Why  I asked was centered around if the new TFT display gets its speedo reading from a GPS, or from the bike itself.

 

Rick

 

[wbw6cos]

Besides, what if rider is not  using GPS?  Does that still have to be synced with phone, or just for navigation only?   

 

Not needing GPS for riding would mean separate, on the bike, speed indication.   

[Hati]

Why not go for a ride without a phone connected to the TFT and see if your speedo still works?

 

I can tell you now, yes it does. 

 

No mass produced two wheeled vehicle on this planet needs GPS to give you speed reading. Period.

[Twisties]

Mine reads within 1 mph of GPS, and matches roadside radar signs as well.  

[Steveyacht]

After seeing this post this morning, I decided to check my speedo against the Google Maps GPS.  I found that it is between 4 to 5 MPH off, the speedo indicates 60 vs the GPS reads 56.  This is on my 2023 R1250RT.  To be honest, I'm quite disappointed as I expected greater precision from BMW.

[Paul De]

Marketing says it is about the schwing factor,   “I hit 140 mph on my bike”….but actually only 130 in the real world.   Doughno why they would do that on a touring bike though.

[kruuuzn]

On 7/21/2023 at 7:44 PM, Steveyacht said:

After seeing this post this morning, I decided to check my speedo against the Google Maps GPS.  I found that it is between 4 to 5 MPH off, the speedo indicates 60 vs the GPS reads 56.  This is on my 2023 R1250RT.  To be honest, I'm quite disappointed as I expected greater precision from BMW.

 

I had the same results with a phone app while the phone was laying in my tank bag.

[mophead]

2022 RT here.  80 indicated is actual 76 by GPS.

 

The 2018 Goldwing I exchanged for the RT was spot on the money.  Only MC speedo I ever had that was accurate.

 

I would run a taller tire but don't think the centerstand would appreciate that.

[Mellow]

Yeah, my '21 is off by 4 to 5 high.

 

Every Honda, Suzuki and Yamaha bike I've ever have has been off by about the same except for the '19 Tracer 900 GT - it was .5 to 1 off.. so close it was hard to catch the difference looking at the gps then back at the speed.

 

I wish there was some kind of calibration that could be done via oem software.

[JCtx]

Rear tires can affect accuracy in 3 ways as well: tire pressure, tire wear, and tire profile; more 'triangular' tires have less error (larger circumference). My 2020 R is only off by only 1 mph, which is the most accurate bike speedo I've ever had. Suzukis were the worst. By the way, it has nothing to do with the TFT. I measured the speed by a highway radar a while back, where speedo read 60, and radar unit said 59, so dead nuts accurate. And of course as the rear tire wears, the error might increase by another mph or so. I'm assuming the speed sensor is located inside the transmission (output shaft), hence only the rear tire plays a role in speedo accuracy. If this is incorrect, somebody please correct me. I searched everywhere how speed is measured on R bikes, and no info. But remember reading somewhere it was on the output shaft.

[dirtrider]

2 hours ago, JCtx said:

Rear tires can affect accuracy in 3 ways as well: tire pressure, tire wear, and tire profile; more 'triangular' tires have less error (larger circumference). My 2020 R is only off by only 1 mph, which is the most accurate bike speedo I've ever had. Suzukis were the worst. By the way, it has nothing to do with the TFT. I measured the speed by a highway radar a while back, where speedo read 60, and radar unit said 59, so dead nuts accurate. And of course as the rear tire wears, the error might increase by another mph or so. I'm assuming the speed sensor is located inside the transmission (output shaft), hence only the rear tire plays a role in speedo accuracy. If this is incorrect, somebody please correct me. I searched everywhere how speed is measured on R bikes, and no info. But remember reading somewhere it was on the output shaft.

Evening JCtx

 

The speedometer input uses the ABS wheel speed sensors. 

[JCtx]

Thank you. And makes sense, since those sensors can do that job, so no need for an extra one. So both tires should be included then. I'm guessing the Road 6 tires that are replacing the stock Z8s are probably going to be dead accurate, since they seem a bit more 'triangluar' than the Metzelers, with maybe a bit larger circumference... and they'll be new. We'll see.

[Steveyacht]

On 2/13/2024 at 7:49 PM, mophead said:

2022 RT here.  80 indicated is actual 76 by GPS.

 

The 2018 Goldwing I exchanged for the RT was spot on the money.  Only MC speedo I ever had that was accurate.

 

I would run a taller tire but don't think the centerstand would appreciate that.

My 1973 Norton, with cable driven Smiths Speedo, is spot on with my GPS.

[MikeB60]

The EU has a very strict standard regarding speedometers. Bottom line is that there is a large fine for manufactures if the speedometers read slow.  

[Bernie]

Your GPS doesn’t always show the exact speed either. It will have a lot to do with the satellites and the rotation of the planet's and the waves of the atmosphere. The only way I know how to find out how fast your are going is to ask your friendly neighborhood State Trooper to clock you and give the results on paper.

[Dave_in_TX]

1 hour ago, Bernie said:

Your GPS doesn’t always show the exact speed either. It will have a lot to do with the satellites and the rotation of the planet's and the waves of the atmosphere. The only way I know how to find out how fast your are going is to ask your friendly neighborhood State Trooper to clock you and give the results on paper.

A GPS usually is more accurate for speed than for position. That's because the position error .mostly cancels out when computing speed.

[Bernie]

1 hour ago, Dave_in_TX said:

A GPS usually is more accurate for speed than for position. That's because the position error .mostly cancels out when computing speed.

Yes, that must be the reason that my iPhone thinks I can travel at 900+mph for 1 sec, while riding my 2023 BMW R1250RT-TFT Bike.

It uses a GPS chip, that gets lost and then can come up with this accurate speed reading?

Or how my Garmin Zumo 550 back in 2008 recorded a momentary speed of 1,600 mph for 1 sec, while I rode from Knoxville to Ashville on a 2007 BMW R1200RT Hexhead? 

I just hope your local constable doesn't use his GPS to figure out the speed you are riding on his highway.

 

[Hosstage]

1 hour ago, Bernie said:

Yes, that must be the reason that my iPhone thinks I can travel at 900+mph

 

1 hour ago, Bernie said:

Or how my Garmin Zumo 550 back in 2008 recorded a momentary speed of 1,600 mph

 

1 hour ago, Bernie said:

I just hope your local constable doesn't use his GPS to figure out the speed you are riding on his highway.

I'm pretty sure you can beat a ticket for going 900mph. Hell, 205 Tilley mostly got off, and that was a ticket for going a measley 205mph! He might have beaten it completely had he stuck it out with a good lawyer.

 

Quote

Quote

Motorcyclist Clocked At 205 MPH Pleads Guilty

Dec 23, 2004 9:54 am US/Central
Wabasha, Minn. (AP) The Minnesota motorcyclist accused of buzzing down a rural highway at 205 mph must complete nearly an hour of community service for every mile-per-hour authorities say he was going.

Sam Tilley, 20, pleaded guilty Wednesday to speeding and driving without a motorcycle license. He was sentenced to a year of probation and 200 hours of community service. Wabasha County Attorney Jim Nordstrom said he dropped a misdemeanor charge of reckless driving.

Tilley, who previously pleaded not guilty to the charges, decided against going to trial on charges that carried maximum penalties of 90 days in jail and a $1,000 fine.

Without a trial, Tilley and the State Patrol won't be able to make their case about how fast Tilley was actually going. In September, a state trooper flying above U.S. 61 in southeastern Minnesota used a stopwatch and road markings to clock Tilley going 205 mph in a 65-mph zone.

But motorcycle enthusiasts -- and Tilley himself -- said they doubted his Honda RC51 could move that fast. Tilley had his bike tested by a mechanic, who said it wouldn't exceed 159 mph.

Tilley wasn't talking about the guilty plea Wednesday and has given few interviews since the incident. The State Patrol didn't comment either.

Legal observers said while Tilley avoided jail time and fines, the community service requirement is far more than the 15 to 30 hours that even a first-time DUI offender often gets.

"If this kid gets past his probation and community service, he could have a future in motorcycle racing," said Joseph Daly, professor of law at Hamline University and a former prosecutor. "He just needs to keep it on the racetrack."

 

 

"

[Dave_in_TX]

7 hours ago, Bernie said:

Yes, that must be the reason that my iPhone thinks I can travel at 900+mph for 1 sec, while riding my 2023 BMW R1250RT-TFT Bike.

It uses a GPS chip, that gets lost and then can come up with this accurate speed reading?

Or how my Garmin Zumo 550 back in 2008 recorded a momentary speed of 1,600 mph for 1 sec, while I rode from Knoxville to Ashville on a 2007 BMW R1200RT Hexhead? 

I just hope your local constable doesn't use his GPS to figure out the speed you are riding on his highway.

 

Notice I said "usualy".

[Fast1]

at 149 mph on the TFT my XT read 140.5 mph max speed

 

at 75 mph on the TFT my XT reads 70 mph

[Steveyacht]

On 3/15/2024 at 12:32 AM, Fast1 said:

at 149 mph on the TFT my XT read 140.5 mph max speed

 

at 75 mph on the TFT my XT reads 70 mph

With the technology that is available today, there is no excuse for a speedo to be off by this much.  My 51 year old Norton has a more accurate speedometer than my 2023 R1250RT.

[dirtrider]

1 hour ago, Steveyacht said:

With the technology that is available today, there is no excuse for a speedo to be off by this much.  My 51 year old Norton has a more accurate speedometer than my 2023 R1250RT.

Morning  Steveyacht

 

That is a good dream but not as doable as most think.

 

What tire (among all the brands) do they use for that fine of a speedometer calibration? 

 

What tire pressure would they use to be that precise?

 

At how many miles of riding from cold should it be that accurate? (cold tire, warm tire, hot tire)

 

What point in the tire wear evolution should they use to remain that precise?

 

At what altitude should they use to keep all motorcycles at one precise calibration?  

 

At what loads on the motorcycle should it be the most accurate?

 

None of the above are one  big contributor but add them all up & that makes precise calibration FOR a specific tire, specific tire wear, specific air pressure, vehicle load, etc very difficult without having the speedometer read lower than actual at certain  traveling  speeds.

 

Electronic Satellite speed reading is probably more accurate than motorcycle based  speed reading but that has it's own issues under trees, in tunnels,  at first ride off until Satellites are acquired, between large trucks, around vehicles with GPS spoofers (mostly trucks), when on the outer range of Satellite angle, snow/ice/mud blocking  Satellite antenna. 

 

Police bikes/cars are pretty close but they use specific police spec tires & a calibrated speedometer (for police tires) that doesn't have to meet the legal requirements of a civilian vehicle.

 

There might be some Radar/Lider speed indication coming in the future so when that is fully vetted it might improve accuracy (at a price obviously) 

 

 

[Steveyacht]

20 minutes ago, dirtrider said:

Morning  Steveyacht

 

That is a good dream but not as doable as most think.

 

What tire (among all the brands) do they use for that fine of a speedometer calibration? 

 

What tire pressure would they use to be that precise?

 

At how many miles of riding from cold should it be that accurate? (cold tire, warm tire, hot tire)

 

What point in the tire wear evolution should they use to remain that precise?

 

At what altitude should they use to keep all motorcycles at one precise calibration?  

 

At what loads on the motorcycle should it be the most accurate?

 

None of the above are one  big contributor but add them all up & that makes precise calibration FOR a specific tire, specific tire wear, specific air pressure, vehicle load, etc very difficult without having the speedometer read lower than actual at certain  traveling  speeds.

 

Electronic Satellite speed reading is probably more accurate than motorcycle based  speed reading but that has it's own issues under trees, in tunnels,  at first ride off until Satellites are acquired, between large trucks, around vehicles with GPS spoofers (mostly trucks), when on the outer range of Satellite angle, snow/ice/mud blocking  Satellite antenna. 

 

Police bikes/cars are pretty close but they use specific police spec tires & a calibrated speedometer (for police tires) that doesn't have to meet the legal requirements of a civilian vehicle.

 

There might be some Radar/Lider speed indication coming in the future so when that is fully vetted it might improve accuracy (at a price obviously) 

 

 

What you suggest is that certain factors can be responsible for speedo inaccuracy, on that I agree.  While I'm willing to accept a reasonable plus or minus factor, 4 to 5 MPH, is unacceptable. Keep in mind that this inaccuracy is always the same, on the optimistic side, indicating 4 to 5 MPH higher than actual when compare to other brands of motorcycles in a group, my car, and GPS. 

If this faulty speedo accuracy is caused by the factors you suggest, why are they always reading high and are consistent bike to bike? That can only be a built-in problem, IMHO.

[dirtrider]

9 minutes ago, Steveyacht said:

What you suggest is that certain factors can be responsible for speedo inaccuracy, on that I agree.  While I'm willing to accept a reasonable plus or minus factor, 4 to 5 MPH, is unacceptable. Keep in mind that this inaccuracy is always the same, on the optimistic side, indicating 4 to 5 MPH higher than actual when compare to other brands of motorcycles in a group, my car, and GPS. 

If this faulty speedo accuracy is caused by the factors you suggest, why are they always reading high and are consistent bike to bike? That can only be a built-in problem, IMHO.

Morning Steveyacht

 

So will you accept a speeding ticket with new tires at full tire pressure to have  the speedometer be accurate within 2 mph @ 60 mph   with about worn out tires with at low end of air pressure? 

[Steveyacht]

A speeding summons for being 1 or 2 mph over the posted limit is as rare as a unicorn fart. Even the police know that there are mechanical variances. Having people pass me while flipping me the "bird" because I'm (unknowingly) running 5 mph below the posted limit is far more a reality than getting a ticket for 1 or two or even three mph over.  Now that I know the speedo has been programmed to be wrong, I adjust my throttle accordingly. 

[dirtrider]

20 minutes ago, Steveyacht said:

A speeding summons for being 1 or 2 mph over the posted limit is as rare as a unicorn fart. Even the police know that there are mechanical variances. Having people pass me while flipping me the "bird" because I'm (unknowingly) running 5 mph below the posted limit is far more a reality than getting a ticket for 1 or two or even three mph over.  Now that I know the speedo has been programmed to be wrong, I adjust my throttle accordingly. 

Morning Steveyacht

 

Very true so that is why a lot of us ride or drive that at the speed limit + 5mph so that puts an inaccurate speedometer on the low reading side back into ticket territory. 

 

The vehicle manufactures need to meet certain speedometer specifications across the board so do calibrate the OEM speedometers with that in mind.  They not only need to meet the USA speedometer reading specification but also in the other countries that the motorcycles are sold in. Germany, the rest of European countries & the USA do not all have the same speedometer standards or +/- acceptance . 

 

The company that I work for runs a speedometer calibration on all our test cars & trucks, and also on a lot the company vehicles,  then a calibration sticker is printed & affixed to the windshield in the upper left hand corner. That has the indicated vs actual speeds mapped out  so at any speed indicated we can tell how fast we are actually traveling. I might drive 10 or 15 different vehicles in a day so no way to keep track of how close each speedometer reads, plus we need the known accuracy for a lot of our testing requirements. 

 

I have a speedometer calibration done on my company vehicle when a new one is assigned to me just so I know EXACTLY how fast I am traveling. I typically don't use a stand-alone GPS in my company vehicle. 

 

 

[strataj]

I've heard it said that BMW authority bikes have accurate speedometer set by BMW.    

[dirtrider]

43 minutes ago, strataj said:

I've heard it said that BMW authority bikes have accurate speedometer set by BMW.    

Afternoon strataj

 

Yes, they are pretty close but depend on police spec tires to be that close. Plus police speedometers do not need to meet the over/under federal speedometer requirements. They also get their accuracy checked/validated  often. 

[Steveyacht]

A question or two. What is the federal over/under specifications for speedometer? Second, why aren't my cars and truck nearly spot on? All three within 1 or 1 mph?

[Hosstage]

This seems a lot of hand wringing over a pretty minor issue.

 

I've had many vehicles that I knew were off for various reasons: over size truck tires, different rear end ratios installed, different sprocket sizes installed, factory speedometers being off (as most are).

I figure out a way to calibrate the discrepancy and go on with life.

 

[Joe Frickin' Friday]

2 hours ago, Hosstage said:

I figure out a way to calibrate the discrepancy and go on with life.

 

GPS works well for this.

[JCtx]

My 2020 R1250R is dead nuts accurate. Remember going 60 indicated in front of a radar on the highway, and it was fluctuating between 59 and 60. I think tires may have an impact on that, since more 'triangular' tires are going to have a larger circumference, and therefore a higher indicated speed. And of course tire wear changes accuracy too, but  maybe 1 or 2 mph? Manufacturers have to be sure not to exceed actual speed, so some just take the easy way out, and be way under, like Suzuki, which is the worst, in my experience. The best has been BMW, but my R is the only one basically accurate so far. I ride solo, tires at 36/40, and my 165# + gear.

[Hosstage]

1 hour ago, Joe Frickin' Friday said:

 

GPS works well for this.

No gps for me, I use the speed radars on the road like JCtx mentions. I assume my speedo runs a couple mph fast, the radars prove this out. (Sometimes I try to see how high I can get the radar to register before slamming the brakes in time to be legal for the zone....)

 

[bimmers]

May have been said before but I was told that EU requires car speedos (probably any motorized vehicle) to be 4km/h optimistic. It was a guy working for VW who claimed that. 

Why would anyone believe the road sign radars are showing an accurate number?? Often they just show dashes.........or "slow down"  wonder why........... "over range" so how they are calibrated no one knows and you would not be given a ticket based on those info signs, traffic speed cameras yes and again calibration is always key.

 

So if speedo is off then all MPG numbers are off too as distance I assume is tied in with speed.

 

And in the end WHO CARES as long as one doesn't get ticketed for absolute number as small as 1/10th over limit. In some countries the are talking about no grace and add to it anything over 0.0 as a limit for DUI. 

 

So final word stick close to limits and be careful. (Oh but in FL you can get ticketed for slowing down left lane even if you are over the limit) so stick to flow of traffic and be safe. 

[wbw6cos]

That really irks me when it shows the dashes, as I am interested in seeing a high number.   

 

(more importantly, I want the vehicle behind me to see it!)  

[bimmers]

What really irks me is to be down here in S FL after having enjoyed the North GA mountains and from there on, while living in ATL for 20 some years..........

[9Mary7]

7 hours ago, Steveyacht said:

What is the federal over/under specifications for speedometer?

10%.......

One of the reasons why 13-15 over was our threshold for a cite.

[Troppo]

Indicated speed is always lower than actual.

 

About 4-5 km/hr in Australia.

[Hati]

13 hours ago, Troppo said:

Indicated speed is always lower than actual.

 

About 4-5 km/hr in Australia.

 

You mean higher, yes?  Actual speed is lower, you go slower than indicated.

 

The amount depends on the vehicle, but ALWAYS slower than the numbers you see. For example: the '21 RT I have is 7 to 9 km/h under indicated speed. The '13 R is only 2 to 3 slower. My work and personal cars are both in your range, identical make and model, vintage is different. Previous cars have been different to all the listed values too.

 

The law in most developed countries is the same, speedo must indicate more than actual speed. Some countries define by how much, others like Australia don't particularly care, as long as the range is right.

 

[JCtx]

The law is not MORE than actual speed; don't remember ever reading that it had to be less. Just not more. But of course basically ALL vehicle manufacturers go lower, to avoid any lawsuits.