Just curious as to the accuracy of the HD speedo.

I know my car speedo reads 8 km slow compared to a GPS in the car. I have been through plenty of speed traps doing what the GPS told me rather than the speedo and never been booked (touch wood)

Has any one compared their speedo to a GPS reading?

best finding one of those permanently marked roads with the 5 km speedo check---cheers Grim

When I got my bike the speedo was out by 6Kph. That was sorted out when I got the bike tuned... I think all speedo's these days err on the side of lower readings.

Dakota digtal make a plug in adjuster that runs between the box and the speedo, I fitted one to my kingy when I swapped out the trans pulley. It basically had two buttons on it one to increase and the other to decrease. fouund one of those 5km speedo checks out the back of bum fuck and went up and down that stretch till I had it spot on--cheers Grim

Speedos can be up to 10% out according to ADR's, but can only read fast, not slow!! Good luck with that!

Yep. I was told by someone in the know that the legislation on speedos is that the needle will show a speed "no faster than indicated"

As in... if the needle is on 100, the speedo is reporting that you are doing a speed no faster than 100kph. So the bike could be doing 95kph - but its not allowed to be 105kph.

from www.racq.com.au/motoring/cars/car_advice/car_fact_sheets/speedo_accuracy

 

The accuracy of vehicle speedos is covered by Australian Design Rule 18. Until July 2006 this rule specified an accuracy of +/- 10 percent of the vehicle’s true speed when the vehicle was travelling above 40km/h.

That is, at a true vehicle speed of 100km/h the speedo was allowed to indicate between 90km/h and 110km/h.

An odometer accuracy of +/- 4 percent was also a requirement.

From 1 July 2006 newly introduced models of a vehicle available on the market must comply with ADR 18/03. Also, from 1 July 2007 any newly manufactured vehicle (excluding mopeds) must comply with this rule.

This new rule requires that the speedo must not indicate a speed less than the vehicle’s true speed or a speed greater than the vehicle’s true speed by an amount more than 10 percent plus 4 km/h. Significantly, this change means that speedos must always read 'safe', meaning that the vehicle's true speed must not be higher than the speed indicated by the speedo.

That is, at a true vehicle speed of 100km/h the speedo must read between 100km/h and 114km/h. An alternative way to look at it is; at an indicated speed of 100km/h, the vehicle's true speed must be between 86 km/h and 100km/h.

Significantly, this change means that speedos must always read ‘safe’, meaning that they are not permitted to read lower than the actual speed of the vehicle.

Additionally, there is now no requirement to have an odometer, and therefore there is no accuracy requirement.

Yup!! that's what I said... just not so eloquently!!

NO ODOMETER??? Serious?? So cars can now run without knowing how far they have gone??

Interesting replies and thank you for all the trouble you all have gone to provide me with some answers.
I always use cruise control on my car hence when I took the readings I was on a straight flat piece of road when I came up with the 8km/h error in the readings.
I also noticed that at 40km/h its only 4 km/h out and as we all know there is no tolerance given by the police in a 40 zone.
Do 1km/h over and your booked. Well at least around here you are.
Shame about the GPS based speedo's though. The lag in mine is only about 1 to 2 seconds which is SFA.
Grim I would have thought it would be very hard to maintain a constant speed over 5km to dial in the Dakota adjuster. Thats an interesting idea though.
Thanks again gentlemen.

Sorry double tap.

Had the gps on my bike and it read identical to the speedo. Same thing, never been booked for using gps as speedo although I have been told it is only accurate on flat roads.

The reason I asked was I read an article a while back on a car speedo that was 10km/h out at 60km/h. He thought he was doing the speed limit and wondered why everyone was over taking him and abusing him.
!0 at 60 is a lot. I also read a similar story in a NRMA mag a few years back.

I avoid speed traps

I avoid speed traps

shit i hit the button twice

my ducati is set an 8% over actually speed .  ie it says 108 when i am only actually doing 100.  i use a gps on longer trips which has confirmed the 8%.  Quite properly ,  the trip computer distinguishes between speedo and actual distance travelled.  

sometimes however , i wish i didnt know this .... as all it has done is to encourage me to go faster yet again

"insert smilie here"

 

hey hey superglide--I meant to say I use the odometer on the 5 km road test--then hit the up or down button--cheers Grim

Ah ok grim thanks. Ill see what the speedo is like when the bike arrives.
Cheers