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Hardass!
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Discussion Starter · #1 ·
Aiight so I thought id check my speedo error on the ZX9 to see if 165 mph was 165 mph. (got bored..wtf?)

Got the GPS on, hit 165 mph on Speedo and GPS showed 169 mph. I kept it at a constant (as much as I wanted to go more, this alone was kinda kicking my ass)

MY question:
How accurate is the GPS to speedo? Last I remembered the higher the speed, the less you were actually going.
 

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I've read here and elsewhere that motorcycle speedos read off anyways - worse at lower speeds, have you tried checking that too? Just curious, when I am riding around at 40mph or 45mph in traffic - I always feel like I am about 5mph under that.

Is it possible to have our speedos calibrated at a shop?

gratz on 165 your so amazing.
Damn, you are a little bitch aren't you? "gratz" on being an ass. :twofinger
 

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Hmm....interesting. Mostly, I've seen the indicated speed on the speedo to be faster than actual. The error is something like 3%. My 10's speedo is off even at lower speeds. I have double verification of this where I have a HUD unit which gets actual speed off a Hall effect sensor on the rear wheel and input of the actual diameter of the tire into the HUD computer along with road side speed radar stations. My HUD and every road side radar station has been in complete sync with each other. While the bike's speedo has been anywhere from 1 to 3 MPH off in overestimating depending on speed.
 

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If GPS is good enough to put a bomb in a 3 foot square, it's good enough to set your speedo healer.

I personally think roadside radars are lying to you so you'll slow down, whereas almost all factory speedometers on all vehicles sold in the US are set to be wrong on the slow side, although I have a Ford Explorer that's wrong on the fast side.
 

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If GPS is good enough to put a bomb in a 3 foot square, it's good enough to set your speedo healer.

I personally think roadside radars are lying to you so you'll slow down, whereas almost all factory speedometers on all vehicles sold in the US are set to be wrong on the slow side, although I have a Ford Explorer that's wrong on the fast side.

There was a roadside radar in my neighborhood a couple weeks ago and since I have different sprockets I figured I would check it. I drove by in the car and the radar read exactly the speed I was going. I drove by on the bike and the bikes speedo read about 5 mph higher than the radar.


I would trust the GPS over the speedo any day.
 

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Hardass!
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Discussion Starter · #7 ·
I really don;t think they test the normal market gps to that rate of speed. gratz on 165 your so amazing.

LMAO-I know I am so amazing.

Reason being for the 165 is because it is about 160mph and up when you lose speed calibration.

I tested 50 - 100 and 165.

The 50 was off by 2
The 100 was off by 1 so I figured give or take.

I am going to recalibrate the GPS and shoot for a lower 150 mph and see if thats where it starts going whack. As for the location-its a private roadway.
 

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I can pass this guy...
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Speedo is off... All speedo's... Even cars. Like BMW puts there speedos off by 7% for some reason... So thats why you should go 40 instead of 35.
 

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Speedo is off... All speedo's... Even cars. Like BMW puts there speedos off by 7% for some reason... So thats why you should go 40 instead of 35.
Is that just on their bikes? I've also heard similar (3%) for the cars, but I've had the GPS in both my M3 and my 328is and both have been spot on up to their respective limiters. Both had roughly stock diameter tires on too.

I've found the speedo on my 7 to be far more accurate than bikes that have the speedo ran off the tranny. Once I get my fuel pump issue fixed, I'll try to get out and see what kind of error I've got at higher speeds.
 

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If GPS is good enough to put a bomb in a 3 foot square, it's good enough to set your speedo healer.

I personally think roadside radars are lying to you so you'll slow down, whereas almost all factory speedometers on all vehicles sold in the US are set to be wrong on the slow side, although I have a Ford Explorer that's wrong on the fast side.
While I'd tend to agree that the GPS would probably be more specific on speed, the civilian GPS's differ very much from the military. My dad's gets within 15' accuracy with 12 satellites, where I'm sure military ones get much much more accurate.

Hehe...
 

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IIRC it's about 6 feet, at least that's what it officially was maybe 8 years ago... I would imagine it's actually much smaller (but classified).

The primary issue is probably that the civilian GPS response time is slower, and it probably doesn't bother to calculate past .1 MPH in velocity.
 

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Silent pipes take lives
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The errors on my bikes are 6.7% of indicated on the Ducati and 10% of indicated on the Yamaha. Both confirmed by pacing various Honda Civics which have that huge digital speedo out for the world to see.
 

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Finally got that ticket
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I have been riding with the assumption that my bike is indication 8-10% faster than actual. I hope I'm right, otherwise I'll be posting about a speeding ticket in the near future. Maybe I'll bring out my Garmin one day and see what it says.

My car (99 Acura 3.0 CL) usually reads about 2-3% faster than the GPS.
 

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IIRC it's about 6 feet, at least that's what it officially was maybe 8 years ago... I would imagine it's actually much smaller (but classified).

The primary issue is probably that the civilian GPS response time is slower, and it probably doesn't bother to calculate past .1 MPH in velocity.
You bet it is. Although, I don't think the response time is the main problem.

Also, for anyone with an Sv, svrider.com people have done quite a bit of research and found that they are off anywhere from 8-13%. I just like to assume mine is 10% off so I can figure out my actual speed more easily. Almost all bikes are off close to 10%. Cars are far more accurate, many times less than 3%.

Of course, changing tire size can affect (and sometimes even correct) your speedo readout too. To the OP: Have you changed your tires to a different size from stock? I would think that your bike would be off much more than you are seeing it.
 

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Live to ride
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LMAO-I know I am so amazing.

Reason being for the 165 is because it is about 160mph and up when you lose speed calibration.

I tested 50 - 100 and 165.

The 50 was off by 2
The 100 was off by 1 so I figured give or take.

I am going to recalibrate the GPS and shoot for a lower 150 mph and see if thats where it starts going whack. As for the location-its a private roadway.
where is this private road way so i can come play too!!??
 

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Speed Racer
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My garmin actually tells me how accurate it is. It all depends on the number of sats it has within range. The more the better.

Normally its between 8-15 feet. I would guess at 100+mph that is a very small distance.
 
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