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CaST
09-25-2005, 04:16 PM
On my cars their speedometers have always been right on the nose when compared to the speedometer of the Garmin 2610..

However, I just got the Powerlet right side plug installed and hooked up my Garmin 2610. Today for a short right the Garmin 2610 had 15 feet accuracy with 7 satellites telling me where I am. However the ST1300 speedometer says that I am going 4.5 to 5 miles faster than the Garmin says at all speeds.

First, which do I trust the GPS or the ST1300? Again on the cars, the GPS has always matched the speedometers. If I trust the GPS, can I adjust the ST1300 speedometer?

Thanks,

Patrick

Ken
09-25-2005, 04:22 PM
The GPS is right. I seem to recall something that can be done to adjust the speedo, but I haven't pursued it.

EDIT: Try this thread for more information. (http://www.st-owners.com/forums/showthread.php?t=5906&highlight=speedometer)

kingprawnokay
09-25-2005, 04:50 PM
GPS is more accurate. I've noticed that motorcycle speedo's tend to be off by about 10% at all speeds. Sorry, I guess I should have been more accurate with all of the mathematics professors on the site.:D
:03biker:

crazykz
09-25-2005, 05:06 PM
I don't know if it is a full 10% off but I'll say about 5%-7%. This is a real issue when you do Ironbutt time rides like 1000 miles in 24 hours or 1500 miles in 24 hours. The GPS is correct and it is what I go by when I ride with it. I rarely if ever use the speedo when running the GPS.

Curt

nm6r
09-25-2005, 05:15 PM
+1, what Curt said.

Ray
http://www.frontiernet.net/~st1300rider/smile04Bikerwheelie.gif

Mark
09-25-2005, 05:30 PM
Patrick,

I use the 10% rule; but, it isn't really correct...

Search for "speedhealer" you'll find Jeff B. uses http://www.speedohealer.com/eng/intro.htm and likes it.


Mark

Kempo-STer
09-25-2005, 07:13 PM
Unfortunately GPS is correct..The speedos are off..which for 14k I feel should be accurate..But since I don't want Paul from Texas coming down on my 'complaining, whining and *****ing', since most motocycles are off this is just fine. (Inside joke :rolleyes: few will get)

crazykz
09-25-2005, 07:55 PM
Funny thing is that the odometer is only 2% off. Figure that in when you're trying to calculate MPG.

Curt

Putt
09-25-2005, 09:57 PM
Speedo healer or Yellow Box hundred bucks..
BC 800 bicycle speedometer around 20...
Greater than 1% accuracy on BOTH the
odometer and speed.


Putt..

CaST
09-25-2005, 10:18 PM
I have instant message on and I am not getting notified.

tricky_micky
09-29-2005, 04:23 PM
Speedo Verses GPS

My speedo is well under the reading given by the Garmin 2610.

At 70 MPH on the Garmin, St speedo reads 65MPH, and so on.

Okay, we could say that the speedo is reading on the 'Correct' side of the law in that you are normally 5 MPH below the speed limit for the road you are travelling on.

However, if you are running on the speedo and are 5 MPH below the speed limit for that particular road, watch out for the trucker or idiot in your mirrors, they may just follow the brown brick road and go straight up yer 'Jacksey'!

I run with the GPS, it gives me a more positive read out, but I am careful if I have to twist the throttle a little as there is a slight time lag before the GPS registers your adjusted speed, this could be enough to trigger a speed camera over here in the UK.

TTFN

Mick

Burger
09-29-2005, 04:49 PM
Here in the UK where we have a gazillion speed cameras there are certain stretches of road where everyone apart from an idiot (or an already banned driver in a stolen car, hm, that would be an idiot) sits rigidly at the speed limit (according to their speedo).

Yesterday, I was on such a stretch a couple of times and I noticed how when I sat at the speed limit I was still a little faster than anyone else. The point being, if my speedo is off, everyone elses is worse :D

Regards,

surfacehilly
09-29-2005, 05:15 PM
i have read somewhere that due to calibration + - error all speedos are set approx 10% lower to take into account this calibration deflection error otherwise manufacturers would be blamed for all speeding if the tried to be spot on as the danger of them being high would have all the trafic agancies going mad, So having said this am suprised that Mr honda would have it wrong

ask a copper ( sorry am from the uk ) law inforcment officer to follow you the danger is if its wrong you get a ticket !!!!!! :bow1:

Simmons1
09-29-2005, 08:38 PM
Mine is off almost exactly 10% as confirmed by a calibrated Sigma.

etalors
08-03-2015, 03:31 PM
No need for adjustments. Just make a mental note of it. The speedo is off by 10% between 0-30. But improves in accuracy to about 5% between 50-100. Here is what I found thru GPS comparison.

Indicated GPS
50 46-47
60 56
70 66-67
80 75

fnmag
08-03-2015, 04:42 PM
No need for adjustments. Just make a mental note of it. The speedo is off by 10% between 0-30. But improves in accuracy to about 5% between 50-100. Here is what I found thru GPS comparison.

Indicated GPS
50 46-47
60 56
70 66-67
80 75

My speedometer is off by much more than your figures indicate.
Yikes, didn't realize this thread is 10 years old.

dduelin
08-03-2015, 04:52 PM
Beware the zombie thread. 10 years in the grave until today!

Saltydog
08-03-2015, 04:59 PM
I use the GPS when driving down the road....but use the speedo when bragging to my buddies about how fast I took that last curve.:biker: :D

Al st1100
08-03-2015, 07:03 PM
here we go again ,,, what is your true gas mileage. After 100k miles on your bike is it really only 90K?? In my opinion there is something very wrong that all st owners know about but Honda is like Sargent Shutlz, know nothing, see nothing...

Al st1100
08-03-2015, 07:05 PM
When I fist got my st I was getting about 48 mpg, using my gps I get about 42 mps... sucks doesn't it

kckbiker
08-03-2015, 07:57 PM
US ST speedo's are typically off 7-8%, but the odometers are supposedly accurate. Thank the lawyers for that. Police speedo's are supposedly spot on. If you correct the speedo with a Speedhealer, the odometer will be off by 7-8%. Choose your poison. Personally, I'd use the GPS for speed and the odometer for mileage.

SMSW
08-03-2015, 08:41 PM
US ST speedo's are typically off 7-8%, but the odometers are supposedly accurate. Thank the lawyers for that. Police speedo's are supposedly spot on. If you correct the speedo with a Speedhealer, the odometer will be off by 7-8%. Choose your poison. Personally, I'd use the GPS for speed and the odometer for mileage.

I think it has to do with individual bikes/tires combination. I put a speedohealer on my ST and kept tweaking it. The calculations did not work out too well for me, because until I got the unit figured out, I was entering correction factors like 30% instead of 3%. Trial and error got mine dialed in,by which time I had the speedohealer figured out and was entering the correct numbers. In a 100 mile run on the interstate, my odo reads .3 mile high compared to the mile markers and gps (both are in agreement), and this was very nearly the same for 1000 mile round trip ride to a rally, including gas stops, restaurant stops, etc. My speedo is reading about 2 mph high at 70 to 75 mph as indicated on the gps.

Before I started my estimated speedo error was around 7% high and the odo was around 3% high. These were estimated numbers - not really accurate measurements because once I discovered how wrong the speedo was, I decided to get the speedohealer and go for perfect mileage and let the speedo fall where it may.

I've noticed that the gps reacts faster sometimes to changes in speed than the speedometer, and that reading that 2mph difference is difficult sometimes. This difference seems to be the width of the hash marks at the 50, 60, 70 mph speeds, and is not easy to discern with a quick glance. Also, there is the needle's lag in showing mph changes.

jfheath
08-04-2015, 10:28 AM
All speedos are not set to be 10% off. Manufacturers (in Europe anyway) have a tolerance range inside which ALL of there speedos must sit. They must NEVER show a speed which is less than the actual speed. The upper limit must not be more than 10% + 5mph of the true speed. And this has to be true for every speedo that they manufacture regardless of the conditions.

Various things affect the speedo reading. Temperature, tyre pressure, how new the tyres are, the profile of the tyre, the load being carried. The manufacturers exaggerate these changes to make sure that they comply with the law.

For example - as the tyre wears down, the diameter of the tyre decreases. As it is smaller, the wheel has to rotate faster to maintain the same actual speed. So your speedo reads higher. Over the life of the tyre, the diameter of the wheel can reduce by about 2%, so the speedo reading will be 2% different from what it was when the tyre was new.

Tyre pressure and increased temperature make the tyre larger. Load effectively squashes the tyre, making the effective diameter smaller.

There are also manufacturing tolerances to take into account. Manufacturers will aim for speedos which sit in the middle of the permitted range. But some will read higher, some will read lower than that middle point.

Satnavs ? Well they can be very accurate, but it depends how you read them. Treat them like a speedometer for a quick glance, and they will not necessarily give the correct reading. Standard satnavs use a distance / time calculation, and the position fix is often subject to error. Mine rarely gets below about 4 yards, one way or the other. Potentially that is an 8 yard error between two position fixes say one second apart. That is quite a big error for speed calculations.

So the satnav will take averages over a number of position fixes. Which take time to calculate. So the satnav never shows you how fast you are going. It shows you how fast you have been going up to this point. And if you do not have a clear view of the sky due to mountains, trees, certain cloud conditions, bridges, tunnels, large artics alongside, changes in speed, ........ the errors will be much greater.

Some satnavs make assumptions about where you are. If you have a route plotted, for example, it will assume that you are on the route, and haven't just deviated. If it loses the signal briefly, it will assume that you are continuing at the same speed. You can observe this if you enter a tunnel slowly and then speed up. The satnav will assume the speed you were travelling as you entered the tunnel, for the entire tunnel length. As you exit and pick up the satellite again, it will briefly report that you are doing (say) 130mph as it catches up with your actual position. (My Zumo 660 does this. My 550 did not).

But given a good view of the sky and a constant speed, a standard satnav is pretty accurate.

SupraSabre
08-04-2015, 11:25 AM
With both my '05 & '04#1 ST1300 speedos are 7% (at least) off, showing higher than the speed I was going!

With the '05, I never did anything about it, other than use my GPS as my speedo!

With my '04 #1, it still has the original speedo. Same, when I ride it, I use the GPS.

With my 2010, the speedo was missing, but I had bought a cop speedo, so I put that on.

With my '04 #2, the speedo was not the original speedo(that is sitting in my parts bin), and because I was able to pick up the cop speedo with only 409 miles, that went on the 2010 and the other cop speedo is now on #2.

Cop Speedo: 166776

A normal speedo: 166775

Note the difference with the hash marks between the miles!

I prefer the cop speedos since they are pretty close to accurate (over 50mph, they are 2mph off, according to my GPS. Even at 90mph) and I don't have to refer to my GPS. It does get a little confusing when I ride the '04#1, but it has been sitting for six months, so I'll worry about that, once I get it fixed.

Stew1300
08-04-2015, 12:08 PM
PUT A SPEEDO-HEALER ON MY 06 4-5 YEARS AGO, CURED THE SPEEDOMETER, I DON'T ALWAYS HAVE THE GPS ON THE BIKE SO THERE'S NO WORRY ABOUT ACCURACY NOW.

Kevin_56
08-04-2015, 12:27 PM
PUT A SPEEDO-HEALER ON MY 06 4-5 YEARS AGO, CURED THE SPEEDOMETER, I DON'T ALWAYS HAVE THE GPS ON THE BIKE SO THERE'S NO WORRY ABOUT ACCURACY NOW.

Same here and there is no lag to deal with.

dduelin
08-04-2015, 12:59 PM
Modern GPS is a marvel of accuracy. Mine updates 60 times a minute and if WAAS enabled actual use data reveals that better than 95% of position fixes are within 1.0 meters and most of those 5% are within 10 meters. I can disable WAAS on my Garmin 550 but there is no reason to. The less than 5% position errors are reduced by averaging to next to nothing. Sure, once in a while it calculates a D/T error to a displayed speed of hundreds of miles an hour but the next few hundred or thousand D/T calculations average the outliers out of the equation. WAAS enabled high sensitivity GPS receivers like that inside the Garmin 550 can be and are used for landing aircraft in zero visibility, so called Category 1 precision instrument approaches. It is extremely accurate if not hidden underground and cut off from signals.

Most the hearsay about GPS error stems from the days of consumer-use single channel multiplexing units using intentionally degraded "dithered" signals back the 80s and 90s. The cheapest ones today sport 12 or 20 channel receivers updating every second or sooner.


On topic, the speedometer on my 05 ST1300 is about 7% off across the range of speed from one end to the other. Of interest to me - the demonstrated speedo error on the Triumph is about 3-4 mph across the entire range of speed. I used to think error had to be linear but the Triumph shows it is not.

st1300r
08-04-2015, 02:56 PM
here we go again ,,, what is your true gas mileage. After 100k miles on your bike is it really only 90K?? In my opinion there is something very wrong that all st owners know about but Honda is like Sargent Shutlz, know nothing, see nothing...

Cars Speedos according to Consumer Reports (2008) who checks their test vehicles.
US tend to be pretty close.
Asian a little optimistic
Germans a little more optimistic.

US commercial vehicle speedo tolerance. +/-5mph @ 50mph
UK 10% max between 25-70mph + 6.25mph and not lower than actual.
Australia had no requirements before speed cameras and depending on the age of your car could be +- 10% and territory governments set ticket tolerances smaller than allowed speedo error.

Odo As for Honda (auto anyway) 2008
Std calibration was +3.something - 1.something.
As a result of a lawyers fishing expedition I think it's now +- 2.5%

The gps is probably within 0.5mph or better with a constant speed straight line. The display will be a little laggy with changes depending on what it's doing between 1 second updates and what ever normalizing routine it uses.

The GPS odo suffers what estimates it makes straight line vs. circular interpolation etc when turning as well as whatever it's doing to reconcile 2d vs 3d space, what the data providers did to provided map projections, and whatever estimates were used to cram the data on the unit.

ymmv LOL.

wjbertrand
08-04-2015, 03:20 PM
GPS receivers actually don't determine current or instantaneous speed using a location / time calculation, rather it's a doppler shift measurement between the satellites and the GPS device.

https://answers.yahoo.com/question/index?qid=20110728073339AA6VczB

SupraSabre
08-04-2015, 04:12 PM
GPS receivers actually don't determine current or instantaneous speed using a location / time calculation, rather it's a doppler shift measurement between the satellites and the GPS device.

https://answers.yahoo.com/question/index?qid=20110728073339AA6VczB

Which is still more accurate than the stock speedos on ST1300s! :o4:

dduelin
08-04-2015, 07:36 PM
GPS receivers actually don't determine current or instantaneous speed using a location / time calculation, rather it's a doppler shift measurement between the satellites and the GPS device.

https://answers.yahoo.com/question/index?qid=20110728073339AA6VczBThat answer isn't true. The system of GPS corrects the distance a signal travels between satellite and receiver in part by Doppler shift but speed calculations are simple D/T between fixed points. In order for position and therefore speed calculations to be accurate Doppler shift is part of the algorithm that precisely fix these points in 3 dimensional space by using signals from three or more satellites. The Yahoo answer seemingly blends GPS with the older Doppler navigation system that used shift of ground based radars to locate a receiver.

http://gpssystems.net/accurate-gpsbased-speedometer/