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There’s several reasons for OEM speedos to read fast.
One is there’s HUGE federal penalties for even one vehicle having a speedo that reads lower than actual speed. Second, there’s tolerances, or margins of error, in every component of the system. Third, tires have tolerances as well, affecting their circumference. Fourth, as tires wear, they get smaller and rotate faster.
I can understand what you're saying...but I don't agree. I've owned a number of cars, trucks, suvs, and motorcycles over the years. The cars and trucks all had accurate speedos when referenced against a GPS unit. My KLR650 was accurate. My ST3...pretty much 10% over. It's completely ridiculous that Ducati sets the speed so high when the vast majority of other manufacturers are pretty much spot on.
 

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Can someone give their errors at different speeds?
Since speed sensors and displays went digital, MOST vehicles will have a specific error in MPH that is constant across the range of speeds.
Like my MTS, where it’s exactly 2mph from 52-110 (the speeds I have checked it at).
EDIT: The cruise setting exactly matches the speedo, which is 2mph off from actual.
The same is true for all my vehicles. Exactly the same variance in MPH regardless of speed.
 

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No. The speedo is programmed to read higher than actual speed by a set percentage. Ducati’s for about the past 15 years were programmed to read 8% fast. It looks like the newer Multistrada have changed it to 5%.

RTFM.



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As long as my speedometer numbers can keep me out of trouble when there's a risk of tickets (or jail) that's all I need it for. Knowing my exact accurate mph is information I have no use for. If my speedo read absolute accurate I'd belooking for a way to make it 5% optimistic.
 

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Discussion Starter #26 (Edited)
The point of this thread was to offer a partial interim solution to the speedometer's tracking error until a speedo calibration unit becomes available.
I don't think we should care why there's an upward bias and discrepancies between models or manufacturers. It is what it is.
I personally am looking for a solution to get an accurate speedometer as opposed to looking at a small number on my GPS. I'm not getting any younger if you know what I mean. A 5% tracking error is totally unacceptable IMHO in this day and age of built-in Nav systems where the speedometer matches the onboard GPS.

I just wrote to a few Speedometer Calibration unit manufacturers to inquire about a unit for recent Ducati models. HealTech (SpeedoHealer) was quick to respond but theirs is not compatible with a CAN BUS communication protocol. I have a few others in the fire right now and will keep you posted with their reply if positive.
 

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No. The speedo is programmed to read higher than actual speed by a set percentage. Ducati’s for about the past 15 years were programmed to read 8% fast. It looks like the newer Multistrada have changed it to 5%.
RTFM.
Read my F‘ing post.

And I’m telling you that is NOT CORRECT on my bike. My bike is EXACTLY 1mph low from 10-50mph, and exactly 2mph from 52mph to 110. My daily commuter has a ten mile stretch of 85mph, then 65mph, then 55mph, all with the cruise set.
I don’t give a crap what the manual says, when there is actual data from which to draw a conclusion. One of the reasons the manuals define a percentage error is to prevent warranty claims for error. If it’s less than the stated tolerance, you have no claim.

My background is as a 20-year traffic homicide investigator. We spend significant time on speedometer calibration, the mechanisms of analog and digital speedometer systems, and how they work. We perform mechanical and function inspections of fatal accident vehicles, and performance comparisons to undamaged exemplar vehicles.
On every vehicle I own, I check speedometer error using GPS and radar.
That’s my background and experience, what’s yours?
 

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Oh. That’s right! I do remember hearing about Ducati building one bike that was totally different from all the other tens of thousands of bikes coming off the assembly line!

I always wondered who got that one.


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Read my F‘ing post.

...
That’s my background and experience, what’s yours?
Traffic investigator or not. You sir are lucky to have a "close to accurate" speedometer on a Ducati. Every Ducati that I'm aware of (and that's not just one, so my sample size just may bit a bit larger than yours) has the same optimistic speedometer. There even was a cottage industry set up to address the speedo errors.
 

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Never saw that speedo post in the manual but doing my own GPS - Speedo math in my head, my 2017 MTS is off 5%.
 

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My 2016 is consistently that 5% off plus or minus some small fudge factor probably related to slopes, curves, and the sampling rate of the GPS and the Ducati Link app. Same with my '13 Hyperstrada before that.
 

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Why does anyone care if it's not accurate by 5% or whatever.
I have a buddy who argued and got out of a 5mph over the limit in a construction zone speeding ticket (there are those cops out there) with his helmet gopro footage. If he was displaying over the speed limit, that would have been hard to do, albeit this is probably a pretty circumstantial case.

I don't do much hooligan riding these days, but I don’t exactly putt around much below the speed limit when I ride either. I never minded a little quick math when checking my speed, but I also don’t think it’s out of the realm of reason to expect to have an accurate display speed for such a high tech motorcycle.
 

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EU design rules, (also Australian, NZ design rules) mandate vehicle speed to show 8% higher than actual speed. If a vehicle doesn't comply (with all design rules) it can't be sold/used on public roads. It's not going to change.
 

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Discussion Starter #35 (Edited)
Riders don't get speeding tickets when looking at their speedometer. They get tickets because they don't look at it or deliberately disregard the speed limit.

Having an upward bias on your speedometer will not prevent you from getting a fine no more than setting your alarm clock 30 min early to get up only to press the snooze button 10 times and being late.
 

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Well the good news, on aging tech anyway, is that the error reverses around 210 vegemite wrappers per hour, at which speed it is exactly correct. After that GPS reads higher. On my '03 ST4S anyway. Had the opportunity on a gunbarrel hwy to test it in 10 kilogram per house steps once and very clear and repeatable. By the time hit 240 actual is 252. Had 264 max showing on Grandpas Procession Sensor for years, chasing a copper on a Hyabusa (another story), but never got to see the needle there. Obviously at these kinds of inrush speeds there is a lot more to do than worry about trifling matters like spring constants of little flicky needle things, gauge hysteresis, static offsets, braking and tyre wear effects on rolling radius, but all this stuff is buzzing about in the ether whilst enjoying the whole purpose of having something to complain about at all.
Seriously, this used to bug me too. Many times I have pushed bikes / driven cars over a set distance, typically 200m, and counted the turns of the speedo cable (put a bit of cardboard on it) then off to the VDO gauge shop to get at least the speedo, and sometimes the odo, set correctly. Speedo is typically just bending hair spring tangs and this is easy enough to have 'a bit of a guess at' in DIY mode, once you figure how to repeatedly open the little suckers and reassemble so they stay waterproof. Odo usually are very accurate in first instance, but need gear changes to fix if for example you have changed diff ratio in a car. On front wheel of a bike not so much of an issue, except for monos where they keep the distance travelled based on speed at lift-off. So the moral to the story for accurate speedos is to do the maths, and keep those monos near vertical so speed doesn't increase and you wind up doing oil changes late!
 

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Just switch the the damn speedo to Kph and stop fretting about what the numbers mean. :)


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Discussion Starter #38
@VinceS
You know Vince, I really like what you wrote but you kinda lost me after "Well the good news..." My ADD kicked in.
For the slow guy writing here, what's the good news?
 

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@VinceS
You know Vince, I really like what you wrote but you kinda lost me after "Well the good news..." My ADD kicked in.
For the slow guy writing here, what's the good news?
The bit people are missing out is that the legal requirement for speedos is that they are slow for legal speeds. After that, other stuff happens, which only ppl debating the subtleties thereof on a forum such as this have any right to know about.

If that's too subtle for ADD consumption, perhaps don't try to add colour to your world. Too dangerous, just let them slide...
 
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