GPS for Speedo

[The Stranger:Me]

So is there any reason why you could not use a GPS for a speedo for warrant of fitness purposes?

[nadroj]

Then you wouldn't clock up all those miles on the dyno!

[sAsLEX]

25 dollar bike computers are acceptable so cant see why that wouldn't be....

[M1CRO:Me]

GPS for Speedo

And here I was, thinking that the subject had something to do with togs

[jonbuoy]

It will be way too laggy and slow to keep up with your speed changes, don't think they will let you get away with it.

[The Stranger:Me]

It will be way too laggy and slow to keep up with your speed changes, don't think they will let you get away with it.

Speaking from experience here or just guessing?
Like you have one or have used one?

Sorry need to check these things as you never know when a poster is coming down with KBitis i.e. Posting unfounded opinion or wild guesses as though it were fact.

[Ixion]

Thee law says "1. A motorcycle first registered in New Zealand on
or after 1/12/1951 that is capable of a speed exceeding 50 km/h must be fitted with a speedometer."

and

"Note 1 Speedometer means an instrument in a motor vehicle that is used to determine forward speed of the vehicle in kilometres per hour or miles per hour."

Therefore, so long as the GPS unit constantly determines (and shows I guess!) the forward speed in kph, it is legally sufficient. Getting a WoF tester to understand this may be another matter.

[Drunken Monkey]

CaN, I can back johnbuoy up on his statement. The GPS does have a small amount of lag between your actual change in speed and the value displayed on the unit. If still in doubt, ask Fish, he works for Navman.

[dhunt]

I'm not sure about the legallity of it but a GPS just can't do what a speedo is designed for.

1) GPS coverage is often poor in NZ especially down south travelling south so you may lose coverage in places.

2) There is lots of lag in GPS - so your burst of speed up to 150km/h and back to 100 may not register your top speed and possibly not register than till you are back at 100 again. That's a little extreme but it proves the point.

3) Tunnels, large built up areas with not much sky coverage will have little or very poor coverage.

4) It can take between 2-15minutes for a GPS to get LOCK so I'm not sure you'll be wanting to sit round that long waiting for it to lock before you drive off.

5) We find GPS's jump round lots in a poor coverage area as it changes satillites etc and I've seen a GPS say we were moving about 7-8knots(12-14km/h) when were not moving.

But hey if you can get it to pass with one, good on you .

[jonbuoy]

Speaking from experience here or just guessing?
Like you have one or have used one?

Sorry need to check these things as you never know when a poster is coming down with KBitis i.e. Posting unfounded opinion or wild guesses as though it were fact.

I use them quite a bit, I also tried using one on the road to re calibrate my speedo after a gearing change. GPS works out your speed over ground from position fixing - it plots your position jumps and works out how long it took for you to do that jump so not 100%. As said by others buildings and tunnels will limit how many sats you can see.

[The Stranger:Me]

I use them quite a bit, I also tried using one on the road to re calibrate my speedo after a gearing change. GPS works out your speed over ground from position fixing - it plots your position jumps and works out how long it took for you to do that jump so not 100%. As said by others buildings and tunnels will limit how many sats you can see.

Yeah thank you. Wasn't trying to give you shit or nothing.
On the subject of gearing changes, the speedo healer works a treat, and using their calculator on line worked great for me. Got my son in the SS to set the cruise control at various speeds and followed him over several km at each speed step to check it. Was excellent using that technique. A dyno probably would be more accurate but I am sure it is close enough that it isn't going to matter.

That said it is out a bit now because of the larger diameter rear wheel (180/55 instead of the 190/50 that is standard) but haven't adjusted it because I will go back to a 190/50 next time.

[jonbuoy]

Ah no bother, yeah I heard about those from this site. I found my gearing wasn't too far out in the end anyway. Must have been over reading before I did the change.

[Ixion]

It depends on what you want. if you actually want a speedo to use - ie tell you what speed you are doing, GPS has some problems. If you just want something to pass a WoF (cos you use the tacho for speed reckoning, maybe) then GPS should be legal

[Motu]

From my point of view it would need to be a permament fixture on the bike - not something you can unclip and put in your pocket.It would also need to clearly show speed contantly - not in the corner of a multifunctional display or not on display as you select another function.A speedometer is required.....an instrument of that primary function.

In short - no,not here.

[sAsLEX]

It will be way too laggy and slow to keep up with your speed changes, don't think they will let you get away with it.

about 1 sec resolution aint they, How often do you check your speed?

CaN, I can back johnbuoy up on his statement. The GPS does have a small amount of lag between your actual change in speed and the value displayed on the unit. If still in doubt, ask Fish, he works for Navman.

Phitek doesn't he?