80 is the new 70

[Kwacker]

At least on my bike.

After the thread I started about my speedo vs one I could see in the car nesxt to me. I have purchased a Sat Nav. So I got to take it on the bike for the first time yesterday. I was very surprised to find that when I was doing 70 on the bike speedo the sat nav was only registering 62/63. It was only when I was doing 80 on the Bike speedo that the sat nav was showing 70mph.

I guess it means that I will have to do a top speed run again at some point just to see how much the speedo is/was lying.

Cant wait to see what the other toys real speed is!

But now the question, How accurate is the Sat Navs speedo?

Kwacker

[RemaL]

I always thought they Sat nav speedo is within 1MPH of your true speed. prob wrong but I trust my Sat nav more then my kit cat speedo and both my other cars read about 3-5 MPH more then the Sat nav. I found this on both my Garmin 500 new sat nav and my Tom tom 910

[TPS]

Most speedos are out by about 3 or 4 mph from new.This is so that they can not be to blame for you breaking the speed limit by saying the speedo on the car said i was doing 30mph when you get done for 35mph in a 30 as it would read 30mph but you would in fact be doing no more than 28mph.
Sat nav systems are nearly spot on in most cases so they should be the more accurate of the two.
Some speedos are calibrated from new and will have a sticker on the speedo face to say they are calibrated.These should unlike a normal speedo be spot on but would need to be checked on a regular basis.

[black-k1]

Legally, new speedos only have to be within 10% of true speed up to 70mph but must NEVER read under actual speed. Therefore new speedoes will always read over and it’s in the manufactures interests to make them read as close to the full 10% over so that your vehicle ‘appears’ to be 10% faster than it really is, does 10% more miles in it’s life and needs 10% more servicing!

[need 4 speed]

All GPS devies are accurate - sat nav, Road Angel etc. If not they wouldn't know where you were and therefore be totally useless.

[y2blade]

need 4 speed said:

All GPS devies are accurate - sat nav, Road Angel etc. If not they wouldn't know where you were and therefore be totally useless.

ditto

2nd only to setting up your own radar/timing-beams speed trap

Edited by y2blade on Wednesday 1st August 10:06

[hardboiledPhil]

Even timing beams have to be set up very accurately though. I have data logger recordings of a friend doing 1/4 mile runs in his car at Elvington and their elapsed speed readings varied by about 15mph over his actual speed at that point.

[podman]

See this recent thread

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Sat nav better than a speedo which can be 20-30MPH out at v max but still not as accurate as a pukka timing trap...