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Ok - I have looked a few times for a previous thread but came up empty. Is it possible to calibrate the speedometer on my 2009 Bonneville T100? Mine says I am going 5 miles faster than I really am. I asked an officer out doing radar to clock me. :D Of course I was in a 30 mph zone. :p He said was going 25 mph. :eek:

Anyway, it is annoying when I am in a particularly heavy patroled area and I find myself doing the math to gage my speed and then re-add what I think is acceptable overage. It would be nice if I could just calibrate the darn thing.
 

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Buy a new speedo or change your front wheel size.
 

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If it's reading 30 mph when you're really doing 25 mph then, in Europe at least, it's illegal. The maximum allowable error is +10%. You have +17%.
Really the manufacturer should come up with a replacement unit under warranty.

The chances are that the error is even greater at higher readings.
 

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Anyway, it is annoying when I am in a particularly heavy patroled area and I find myself doing the math to gage my speed and then re-add what I think is acceptable overage. It would be nice if I could just calibrate the darn thing.
Why not just go by the speed reading and not fret about the difference? If your speedo read slower than actual, you might have a problem but otherwise you're just not riding quite as fast as you're allowed to.

Is absolute numerical speed that important?
 

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Is absolute numerical speed that important?
It can be if you have a huge truck following you on a dark and rainy motorway. He will have a calibrated speedometer for his tachograph, say you're doing 60 mph on your speedo when you're really doing just over 50 with that amount of error.

Don't blame the trucker for getting up your backside. He's allowed to do 58 mph and he has an accurate speedo.
 

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Mine's been that way for over 3 years

In this area, the cops will occasionally set up an unmanned radar with a large display. Typically reads like "Speed Limit 45 .... your speed is (whatever appears on the display). My speedo reads about 5-6mph faster than I'm going, even at speeds as low as 35mph. 40mph on speedo = 35mph on the radar. Now that I know the amount of error, I work around the problem.

Bob
 

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I used my GPS to check the speed on my 2008 Bonnie Black, and the speedometer was almost exactly 5 mph over the correct speed at all speeds above about 15 mph. So the discrepancy is not proportional to speed. If your speedo is like mine, just subtract 5 mph from whatever it indicates. It's a lot easier than replacing the whole unit.
 

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This is strange. Every time I have checked my '08 it was nearly dead-nuts.

Unless of course - every single radar I have passed was off by the same amount.

I guess I'll have to strap ,my GPS on this thing and see for sure.
 

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My 2006 T100 is off by 5 MPH as read from 3 GPS's. It isn't off 5 mph at 30 & 10 mph at 60. That would be a calibration problem. It is also off 5 mph on the radars that they put in school zones. It is like the needle was put on the shaft 5 mph too fast. Also look at the zero to five mph scale. It isn't there. If I could get my speedo apart & move the needle back it would read right. So for the last 22,000 miles I just subtract 5 mph from the reading. Or ignore it.
Now the tachometer. That thing is junk. Jumps all over the place. I might as well have a regular Bonnie without tach. 357Bob.
 

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inaccurate Speedometer

Inaccurate speedometers on Triumphs have been well documented here; it appears to be the norm; both older bikes 02-03 etc. and newer ones. I guess it's too much of an engineering challenge for Triumph. We just have to remember to add 5, 7 or whatever mph to our readings.
 

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The conspiracy theorists have long suggested that these errors are actually in-built by design!!
Not only on our Triumphs but in ALL vehicles!

Think of it. Its an ideal way to slow traffic down, save fuel, save accidents, save the environment etc etc etc.

Its true that it would seem that when people report their speedo's being inaccurate, its generally always in the same direction (reading fast).
Rarely is the error the other way!!

I have to say that since the advent of the GPS, I've found every vehicle I've had (cars and bikes) have always shown an (aprox) indicated error of +5mph.

Conspiracy or not I dont know, but logic would suggest that if the errors were down to inaccurate design and calibration then they would be pretty equally + and -

But they're not!!



V.
 

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I don't go along with the conspiracy theory, but I would suggest manufacturers deliberately set the speedos to read fast so that they don't have to go to court every second day because someone got booked because the speedo was reading slow. Set it to read fast by 5mph, and you have a pretty good margin to stay of trouble, the speedo would have to be pretty crook to start reading slow..I believe the term is covering your donkey, or something like that..
 

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Under EU regulations they're not permitted to under read by any amount. As making them accurate would be costly, the makers err on the side of caution.
 

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I strapped my Garmin to my handle bars and checked mine. Seems it's about 10% high on the speedo. ie: 33mph on bike = 30 on GPS, 44mph = 40 GPS, etc. Ten percent makes the math pretty easy. 2008 Bonnie Black.
 

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Burned out a bit coming home on a ride yesterday trying to beat the rain. Hit 95 on my speedo (09 SE) and my dad's GPS said he hit 90 max. (I was following him) Seems as if the +5 after 15 or so is accurate in my case.
 

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Way off for me

Been meaning to post about this for a couple of weeks since I started riding regularly with my GPS (thanks, D9!). My speedo on my Bonnie SE is WAY off- at 70 mph indicated I'm just barely over 58mph on the speedo!

This explains why I'll be tooling along at "75" and a bluehair in an SUV blows by me on the right.

I mentioned it to the dealer yesterday during my 600, er, 800 mile service and the response was a *shrug*.

So, for me, I'll be adding 10mph at any speed that matters (50 and above).
 

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Been meaning to post about this for a couple of weeks since I started riding regularly with my GPS (thanks, D9!). My speedo on my Bonnie SE is WAY off- at 70 mph indicated I'm just barely over 58mph on the speedo!

This explains why I'll be tooling along at "75" and a bluehair in an SUV blows by me on the right.

I mentioned it to the dealer yesterday during my 600, er, 800 mile service and the response was a *shrug*.

So, for me, I'll be adding 10mph at any speed that matters (50 and above).
Wow, that's WAAY off. Not sure about the wifeys Bonny, my ST is pretty close but I run with a GPS at all times and use that when I'm really concerned. Out here driving too slow gets everyone up your backside, by too slow I mean not going at least 10 over the speed limit, and they will drive dangerously to get around. I watched some bimbo on a cell phone keep swerving into the wrong side of the road trying to find a way around my wife, when we were going a bit over the speed limit already.. not fast enough for this idiot.
 

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I'm high!

At least my speedo is... I've put 3,500 mi. on my '09 Black Bonnie in the seven weeks I've owned her. As I don't run GPS, I'm noticing that every one of those friendly "Yer goin' this fast" radars set up on the street put me at a minimum of 10 mpg below what the speedo sez. I make sure to pace a car if I'm in traffic, just to make sure the radar sees me (or the car I'm pacing).

At first I read here that 5 mph was the rule, and once I got my brain wrapped around the constant math, I was doing okay. But now that I've kinda verified how off the speedo is I don't know what to believe.:confused:

Further, does this affect the odometer? Does that mean my gas mileage ain't what I've been thinking it is (~50 mpg)?:rolleyes:

The only time I really give a flying is when I either notice law enforcement or myself flying past traffic!

Sheesh!
 

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If we could find out the mph per 1000 rpm figure, then we could use the tacho to do the corrections. Tacho's are electronic pulse counters and fairly accurate.
 

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Inaccurate speedometers on Triumphs have been well documented here; it appears to be the norm; both older bikes 02-03 etc. and newer ones. I guess it's too much of an engineering challenge for Triumph. We just have to remember to add 5, 7 or whatever mph to our readings.
Actually you need to subtract instead of add, as in if your reading is 60 you're actually going 53-55.
 
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