Which MPH is acurate - GPS or Speedo?

I can't see why a calibrated police spec speedo would not fit straight in a standard bike. I have the police ST11 and speedo looks the same, apart from the 2kph increments. The speedo drive is the same as the civilian version. Speedos can be calibrated, but the cost is probably prohibitive.
 
I know this thread has been beaten like a dead horse, but...

Honda Speedo 110 MPH - Garmin Zumo 550 = 100 MPH
Honda Speedo 100 MPH - Garmin Zumo 550 = 91 MPH
Honda Speedo 90 MPH - Garmin Zumo 550 = 82 MPH

THATS ALL I WANT SAY :) :confused:

OH Yea... :wasntme

That's it...
 
I have verified that my ST speedometer is off 8% by riding next to two different new Honda Civics. The new Civic has a large digital display of the MPH which I believe to be very accurate. This display can easly be seen while riding next to the car.

Every motorcycle I've owned has about this same speedometer error. Very disconcerting to be to always have to recalculate the actual speed. I am disappointed at this trait in the ST. The temprature gauge seems accurate to within one degree, why can't the speedometer do likewise? (are you listening Honda = is there a fix for this?)
 
I am bumping this thread.

The reason? When my Sumo 550 reads 65mph, my ST will read 70. There's always been a 5mph difference between the two at highway speeds. I figured everyone had that, and I figured it was Honda's Speedo at fault.

However, I flipped my Official ST-Owners Calendar to August today. I looked at the picture of Indypup's ST1300 cockpit that's pictured. His Sumo 550 and his Speedo indicate the exact same number of 61mph.

So... I'm just sayin'...
 
RideOn said:
My Garmin 2610 reads 65 mph when my ST1100 speedometer reads 60 mph. Seems like a pretty big difference. Which should I believe? I tend to believe the Garmin.
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Speedos vary. They are built to a tolerance. Normally you would expect some to read over and some to read under, with the vast majority being more or less correct. Not speedos. The dials are put on so that all of them read under the actual speed. Some will be a tiny bit under. The majority will be a fair bit under and a small proportion will be a lot under.

The only way to really test is to do a timed run over a measured distance. Here in UK we have measured miles in various places, and motorways have accurately positioned and numbered marker posts every tenth.

The GPS on the other hand tells you how fast you have been going. Not how fast you are going. The reading can be inaccurate - depending on where it thinks you are. And note that the Zumo estimates where you are some of the time - for example- it assumes you are on the road. It also assumes how fast you are going if it loses a signal. (Eg watch how it behaves when you enter a tunnel). You can observe this behaviour if you turn off onto a road that runs parallel the one that it thinks you should be on. It often doesn't recognise that you have turned off. Even though it is getting a fix on you, it is happy to accept and 'correct' the error to where it thinks you ought to be. However, if you are on a straight road and do not alter your speed and it gives the same reading for some time while you are watching, then its speed reading will be very accurate.

I've done the measured mile test at various speeds and compared it with the speedo and the zumo. I know that my zumo tells me 70 mph when the speedo tells me 76mph, and my calculated speed (timed) tells me the zumo is right.
 
EASt said:
I am bumping this thread.

The reason? When my Sumo 550 reads 65mph, my ST will read 70. There's always been a 5mph difference between the two at highway speeds. I figured everyone had that, and I figured it was Honda's Speedo at fault.

However, I flipped my Official ST-Owners Calendar to August today. I looked at the picture of Indypup's ST1300 cockpit that's pictured. His Sumo 550 and his Speedo indicate the exact same number of 61mph.

So... I'm just sayin'...
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Can you say " Speedohealer " ?
 
Aah folks - listen up.....

In the same vein that an analogue watch that does not work is more accurate (twice a day) than a watch that loses 5 mins for every hour (accurate once every twelve days).... then....

Both the speedo and GPS are equally as accurate if there is a CONSTANT % difference! ner!

You could only imply that the GPS reads a speed CLOSER to your actual velocity.

So, if you're in a 60 zone and ride at an indicated 64-66, you'll be OK every time - yes?

Taking into account the exchange rate on the Greenback - that is my 2.416 cents worth. :D

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Speedo healer to the rescue.It takes a number of trials to get the correct info re speed comparison using a GPS.That done a Speedo Healer can make the speedometer dead accurate.Also keeps your odometer from saying your bike has more mileage on it than actual.Cheers Y'all.
 
My 2cents worth...
We just got back from a trip in the northern California Coast area. I passed 3 of those "slow down" signs with the radar and each time it read 4mph lower than my speed-o. Which kinda confirms the ST is generally set a little high by around 5-7%
 
Simplest way to find out is to blow by your favorite local LEO at 65mph in a 45 mph zone. When pulled over he let me know my actual speed was not 65 as indicated but actually only 63!

Now the only question is - Is my speedo or his radar gun more accurate:think1:


PS: Schmoop has me thoroughly confused...I've read and re-read his post and all I can say is "Huh?"
 
The odds are that the radar gun is accurate to within a few hundredths of 1 mph, and will have been calibrated in a Lab. Or should have been if its expected to use the readings as evidence in court.

As for Schmoop, he is from Queensland...... :D:D:D:D
 
I have a Garmin Zumo 550, after 35mph The ST 1300 speedometer is always 5 to 7 mph faster than the Garmin, which I am guessing is the more accurate
 
Heck, just the other day, I was on my ST1100 in a residential neighborhood, and was doing 35mph indicated.... the "your speed" sign said 30.

I don't have a GPS unit (or a mount for my smartphone which has GPS), so I haven't been able to verify, but I'm pretty sure the speedo on the bike indicates FASTER than actual speed.

My previous two bikes, Yamahas, as well as my Porsche were the same. They were up to 10% off at freeway speeds.

This is normal. This is almost a 'safety buffer'. If your speedo says you're going faster than you actually are, then if you're going the speed limit according to your speedo, you're actually going slower - less chance of a :policeST: hitting you up for $$$.
 
barto said:
PS: Schmoop has me thoroughly confused...I've read and re-read his post and all I can say is "Huh?"
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What can I say.... at the time that WAS what the greenback was worth. :p::p::p:

Plus Avtrician - I may be a banana bender now, but I am a sandgroper by birth. :D

That statement should raise a few American eyebrows eh mate? ;)

Regards, Dave

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Schmoop said:
What can I say.... at the time that WAS what the greenback was worth. :p::p::p:

Plus Avtrician - I may be a banana bender now, but I am a sandgroper by birth. :D

That statement should raise a few American eyebrows eh mate? ;)

Regards, Dave

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Strine has always fascinated me. Mom's mum was an Aussie... and per her, I have a ton of rellies there. Met and hung out with one of mom's cousins in 08 when he and his wife visited. I'd love to get down there some day and look up all of my extended family. Would be a blast if I could rent a bike and do some riding.

Except for that whole riding on the wrong side of the road bit, that is!


We'll hope no one chucks a wobbly about the terms... us yanks might think they're racist or something!
 
That'd be ripper Fray - we'd love to give you a butcher's hook around the place. Hit the frog and toad for a bo peep and a few sherbets. You guys are always welcome.

But you'd have to reciprocate. I love how you guys have "BBQ restaurants" right on the roadside, and I would especially love to do a National Parks Tour including Monument Valley, GCNP, Crater Lake, BRP, & the redwood forest/s - one day.

Oh, and ACL would kill me if I didn't throw in Moonshine as well!!!

Dave ;-)

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Warning, Thread drift....:D

Dave, that makes you either a sandy nana, or a bent groper.

OK we speak funny in Oz, but at least it sounds the same all over the country.
 
Well, Schmoop, butter my buns and call me biscuits! If you're ever in my neck of the woods in Texas, I'll take you for some mighty fine BBQ. ;)

Oh, and to be on topic... something about speedometers... and miles and stuff. There. I stayed on topic!
 
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