Analog vs Digital speed indication and (GPS)

[ecbaatz]

Well, I tried an experiment this afternoon with the stock gps and it raised an interesting question.

 

There has been discussion on the difference between the analog speedometer and the digital one. There were questions on why the accuracy difference.

 

My thought was that the front wheel provided the speed indication for both analog and digital. So to prove this theory I did the following.

 

I put the but on a trailer, had some one tow me while I videoed the speedometer and GPS. In addition I had my Garmin Xumo Xt installed as well so we would have a base line.

 

As I was recording it I did find out that there was no speed indication neither analog nor digital which is what I was expecting. The shock was that the stock gps was not indicating the travel. It stayed on the starting point of when I began the test. I did record both in accessory and with the bike running to see if there was a difference. There was none.

 

I stopped and shut the bike off and to just check I started it back up to see if the stock gps would find the new location. Which it did.

 

I cannot explain why the stock gps did not show the travels. So that is the new question. The Garmin Xumo did show the travel.

 

So now I have to see if I can figure out why.  I do hope this answers some questions. Or it may just generate more, I know of at least one.

[ChiefGunner]

11 hours ago, ecbaatz said:

Well, I tried an experiment this afternoon with the stock gps and it raised an interesting question.

 

There has been discussion on the difference between the analog speedometer and the digital one. There were questions on why the accuracy difference.

 

My thought was that the front wheel provided the speed indication for both analog and digital. So to prove this theory I did the following.

 

I put the but on a trailer, had some one tow me while I videoed the speedometer and GPS. In addition I had my Garmin Xumo Xt installed as well so we would have a base line.

 

As I was recording it I did find out that there was no speed indication neither analog nor digital which is what I was expecting. The shock was that the stock gps was not indicating the travel. It stayed on the starting point of when I began the test. I did record both in accessory and with the bike running to see if there was a difference. There was none.

 

I stopped and shut the bike off and to just check I started it back up to see if the stock gps would find the new location. Which it did.

 

I cannot explain why the stock gps did not show the travels. So that is the new question. The Garmin Xumo did show the travel.

 

So now I have to see if I can figure out why.  I do hope this answers some questions. Or it may just generate more, I know of at least one.

 

Hey @ecbaatz, there are some things that may not be powered up until the bike is running. I’m surprised to see you didn’t see if that made a difference.

[ecbaatz]

Oh I did it in both accessory and the bike running. You just might not have seen that part as I had to shorten the video to get it to load here. 
 

 

[saddlebum]

Location has an effect as well. In Ontario  there is a 2 Km difference between my GPS and my speedometer. In Nova scotia they read identical.

[BigBlueVenture]

Any updates to your original post? My bike seems to be about 10Kph out and the GPS always read what the speedo gauge says. My 110Kph is actually 100 when verified against several different bikes, GPS's and automobiles. Being out 5 or 6 clicks is understandable but 10 out seems just wrong. Anyone else experiencing this? 

[saddlebum]

On 10/23/2021 at 9:13 PM, BigBlueVenture said:

Any updates to your original post? My bike seems to be about 10Kph out and the GPS always read what the speedo gauge says. My 110Kph is actually 100 when verified against several different bikes, GPS's and automobiles. Being out 5 or 6 clicks is understandable but 10 out seems just wrong. Anyone else experiencing this? 

I am not that well versed on the 2021 bikes but dealing  with electronics on transport trucks and assuming the speedo on these bikes are based on pulses per mile derived from a wheel speed sensor I have to wonder if this could be a calibration issue. On trucks we take into account the tire revs per mile and the the drive line ratio. Using a specific mathematical formula we derive a figure referred to as pulses per mile. this figure is then programmed into the ECM. to get the correct reading at the speedometer.

[VentureDog]

The speed indicated on the electronic display (GPS screen) is not the speed determined by the GPS signal, but rather from the vehicle speed sensor - the same one that powers the analog speedo.  You can confirm this by disconnecting the speed sensor - both the analog and digital speedos will indicate zero.  My 2018 SVTC is off by 9 km/h at 100 km/hour speed (when the speedos read 100, I'm actually only going 91 km/h as confirmed by a real GPS and also my car speedometer). I use a Garmin Zumo for actual speed and reliable directions.

[BigBlueVenture]

Thanks. That makes me feel better as my speedo is also off by 10kph it seems on average. Annoying but I guess I'll have to live with it. I am disappointed that the GPS speed indicated is not satellite calculated as one woukd expect. 

[saddlebum]

There has for long time been this theory that Yamaha deliberately set their speedometers to read higher than the actual vehicle speed whether it is for some safety perspective or just to make it seem like your going faster than you think you are, or whether it is to ensure the vehicle never goes faster than the legal road speed by assuring any speedometer error is below speed limit not above.