speedos vs sat nav

[ddtwelve]

which one has the correct speed the gps sat nav or speedo on bike/car ??

[dickturpin]

I understand speedos only have to be with 10% so satnav will be more accurate

[dolau]

Yep- satnav

[1967fazer]

Sat nav much more accurate, but speed count is about 3 seconds slow....I think

[Bracechenko]

Sat nav much more accurate, but speed count is about 3 seconds slow....I think

Ummm....I also believe that a lot of sat navs are only accurate if travelling along a flat expanse. Any elavation and that will affect the accuracy

[FuZzBoM]

There are way to many factors to take into account. generally a satnav will be closer to the mark but this depends on how good a signal it picks up and from how many satellites. most will give an accuracy reading if you look in the settings.

I have also found most speedo's will be roughly accurate to about 70mph and get further off the mark the faster you go.

[1967fazer]

Thankfully, I've never had cause to test the accuracy of my satnav, I usually drive to my speedo anyway (honest officer)

[Bracechenko]

I use this radar guided sign that shows your speed as you past in green numbers if under or on the speed limit and red if above....seems to match my speedo at 50mph but wonder if the government set that up with a % inbuilt too?

[BBROWN1664]

Satnav is more accurate in a straight line on a level road at a constant speed. Other than that, it's anybodies guess.

[Motorbreath]

The FZS 600 speedo shows 5% less speed than the actual, as an italian magazine tested.

[donkey93]

my speedo reads almost the same as gps within 1/2 mph at any speed and when i have been out riding with mates my bike is normally covers 10% less miles than they do

[ddtwelve]

My car is usually way out have to do a indicated 85 to get 75 on the satnavi thingy

[ghostbiker]

my speedo was pretty much perfect with the satnav and a comunity speed gun. but i run a speedo healer that removes the speedo error and adjusts it for the sprocket change i have as well.
but recently i changed it to allow for the sprocket only as it was driving me mad in roadworks when most of the traffic was doing 46/47 in a 50 and the like lol

[BBROWN1664]

As your tyres wear the inaccuracies increase by 2-5% too.

[Captain Haddock]

@Ghostbiker, does the thou have the speedo driven from the gearbox then? I thought they were all still driven from the front wheel and the dreaded plastic lugs of mass breakability.
Or did you put the sprockets on the wrong end of the bike? (easy mistake after the pub...)

In a straight line at constant speed satnav should always outdo a speedo but will never out brake or out accellerate a bike due to slow update/calculation times, the accuracy readout of satnavs is just an estimated guess, to know how far out it was it would have to know exactly where it was to start with so would be 100% accurate, then you start getting into the technical side of waas/egnos/differential gps...

[ghostbiker]

All I know about the speedo is I plug in a gear indicator to the loom and my speedo healer into another part of the loom. So I think it must pick up electrical signals from maybe the ecu for revs and gearbox for speed. But that's. Guess. Deff not cable or electrical from a front wheel drive LOL. Just how old do you think. Gen 1 is :P

[painterlad]

personally I prefer speedo's