Inaccurate speedo on 1150gs fixed

[RayS]

Over reading Speedo

I recently did a RoSPA advanced riding test on my 05 Adventure. The test examiner was the serving Police chief m/c and car instructer for Suffolk.

I told him before the test that I believed my speedo was over reading (checked against a friends GPS) and should I therefore keep to the speed limit as indicated by the speedo or go a bit faster than my indicated speed during my test.

Of course he said use the speed indicated by the speedo but that during the test he would check it against his calibrated BMW police bike speedo. He found that my speedo was consistently over reading by 8% to 10% throughout the speed range. ie. at an indicated 70mph I was really doing 63/64 mph, at an indicated 40mph I was really doing 36 -37mph etc.

He said this is normal as manufacturers cannot risk supplying a speedo that under reads and thus to avoid prosecution they ere on the side of caution and often allow 10%.

So I now know that I have 10% in hand against my indicated speed throughout the range, which is very useful. I shan't bother to try and recalibrate the thing.

Incidentally he pointed out that as most bikes over read by 10%, when someone is picked up with "are you aware sir that you are doing 85mph" then their speedo is probably reading something like 95mph!!

I passed the test and got a Silver by the way.

Cheers
Ray

 

[Rollo]

He said this is normal as manufacturers cannot risk supplying a speedo that under reads and thus to avoid prosecution they ere on the side of caution and often allow 10%.

So I now know that I have 10% in hand against my indicated speed throughout the range, which is very useful. I shan't bother to try and recalibrate the thing.
Ray

Interesting how BMW have this policy on bikes and not on their cars. The 3 BMW cars I've compared my GPS with have been spot on as far as I can detect, as have my Saab Aero, wife's Micra, son's Fiat and daughter's Corsa. Also, my two mates with Pan Europeans have theirs spot on (checking by glancing at the two).

If you research the Adventure Riders website you'll find this is a big issue, recognised by dealers world-wide, but apparently ignored by BMW. For what reason I know not, but I don't buy the 'err on the cautious side' by 10% at all !

Are there any electronic speedos in the BMW bike range and, if so, are they 10% out for safety ?

I wanted it accurate so that I serviced it at the right time and I tend to use the speed limit plus 10%, plus 3 mph.

Couldn't easily calculate speed limit plus 10%, + 14%, + 3 mph whilst on the move, but you'll know that's 41 in a 30 and 78 in a 60 mph zone, I suppose.

Rather spend the £20 than feel any comfort from my speedo reading 78 mph in a 60.

As your's is 10% out, does that mean you pass through a 60mph speed camera with a reading of 66 mph on your dial? If you do, you're a brave soul - my response doesn't need "sorry Officer, my calculation led me to believe I was within the law"



Bar room stories are better though, "autobahn at 130 mph on my Adventure, 53 mpg ...."

 

[BBB61]

My old 1150GS had a speedo and odometer that over-read by about 10%. By changing the speedo drive over to the R1100R item, it bought the over-read down to about 3%, which was much more acceptable.

My current R1200GS is much better. At an indicated 100mph, the GPS is showing 98, and the odometer when compared to the GPS mileage reading is only over reading by 0.3%. The speedo over read throughout the speed range is only 2mph when compared to the GPS.

As for my Triumph Sprint ST, this is over reading by between 15-20%! At an indicated 36mph, the GPS is showing 30. When the GPS is showing 60mph, the speedo is showing 69! But the odometer is accurate to within 1%. Triumph so far have shown a reluctance to investigate this.

Current EU regs say the speedo must never under read. When tested for conformity, the maximum over-read allowed is 10% + 2.5mph. However, when the speedo is fitted to a production vehicle, the EU regs allow an over-read of 10% + 5mph. Which would allow a speedo reading of 38mph whilst doing a true 30, or a reading of 71mph at a true 60.

 

[Iain Hogg]

Current EU regs say the speedo must never under read. When tested for conformity, the maximum over-read allowed is 10% + 2.5mph. However, when the speedo is fitted to a production vehicle, the EU regs allow an over-read of 10% + 5mph. Which would allow a speedo reading of 38mph whilst doing a true 30, or a reading of 71mph at a true 60.

I do believe that these limits only apply up to 70 mph (?), after that, they can read what they like

Iain

 

[guitarman]

.............................

I wanted it accurate so that I serviced it at the right time and I tend to use the speed limit plus 10%, plus 3 mph.

Couldn't easily calculate speed limit plus 10%, + 14%, + 3 mph whilst on the move, but you'll know that's 41 in a 30 and 78 in a 60 mph zone, I suppose.

......................

Jeez, what complicated lives some people have

 

[Rollo]

Jeez, what complicated lives some people have

Obviously, just making a point.

With an accurate speedo, life is not complicated. Not knowing where you're at, is.

 

[RayS]

As your's is 10% out, does that mean you pass through a 60mph speed camera with a reading of 66 mph on your dial? If you do, you're a brave soul - my response doesn't need "sorry Officer, my calculation led me to believe I was within the law"

Yes and No .... I do now go through 40mph speed cameras at an indicated 44mph and I have been followed by the boys in blue for several miles recently at an indicated 77mph, both without any problem ... so far. It's not too difficult to calculate and go at 33mph in a 30 limit, 44mph in a 40 limit, 55mph in a 50 limit etc etc is it?

Living dangerously?
Ray

 

[Rollo]

Yes and No .... I do now go through 40mph speed cameras at an indicated 44mph and I have been followed by the boys in blue for several miles recently at an indicated 77mph, both without any problem ... so far. It's not too difficult to calculate and go at 33mph in a 30 limit, 44mph in a 40 limit, 55mph in a 50 limit etc etc is it?

Living dangerously?
Ray

Try it with 14%. And what about the Chief Constable accepted leeway?

 

[ELIMINATOR]

No one's mentioned service intervals. If we stick to these, then we'rer being ripped off.
6k =5,4 12k= 10,8 18k=16,2 24k=21,6 30k=27 36 =32,4 42=37,8 48=43,2

So they make more money out of servicing, whilst at the same time letting us think the mpg is 10% better than it really is?

 

[BGF]

So which is the right modded part to go for? So far 2.9, 2.85, 2.65 have all been mentioned

 

[Ted]

Speedo Correction

Found this on a US site.

Off an R1100R with wire wheels. part no. 6212230653 ratio 2.875 : 1

Worth asking a dealer if its still a valid part.

 

[sniper]

So which is the right modded part to go for? So far 2.9, 2.85, 2.65 have all been mentioned

The 2.85 is marked and sold as a 2.9 this is the one i used. Got it from Sherlocks next day. My original one packed up , i would not have changed it otherwise .

 

[oblertone]

count me in !

I for one will be following up on this as my speedo ('97 1100) is woefully inaccurate and been a constant irritation because of it, thank you & good night !

 

[Rollo]

So which is the right modded part to go for? So far 2.9, 2.85, 2.65 have all been mentioned

The error varies by bike for some reason so best to find what you have fitted and select one of lower ratio depending on the variance you measuure.

I had to go all the way to 2.65 on my Adventure to counter the 14% difference. Check Adveriders to see what fix is most often used for your steed.

 

[BarkinDogs]

I've been going 'round with bmw about this. The official line is that the speedo intentionally reads 5 to 10% high. They assure me that the odo is accurate.


It ain't accurate, it's 5.5% high. Among other things that means my 36,000 mile warranty is 1,980 miles short. The two local bmw shops say that's just the way it is, live with it. Now i've got bmw motorrad involved and they are at least considering looking at it.

Interesting sidenote, in the US it's a federal crime to knowingly sell a vehicle that does not accurately log miles driven.

 

[GSAde]

Who ever said that any speedo reading inaccuracy would be duplicated in the odometer?

The odometer will be directly driven by a gear from the wheel while the speedo needle is moved by induction from a spinning magnet close to a spring loded disk. Perhaps "correcting" a 10% overread in your speedo by changing the gearing is introducing a 10% underread in your odometer

And I still maintain that the GPS is no good for "instantaneous" speed indication, it can only give you the average speed over the straight line distance between the last two updates.

Iain

GPS ludite 'cos I can't read them without glasses!

The odometer on my GPS shows exactly the same percentage error as the speedometer on it i.e. 10%. Hence it would appear that the bike's odometer is over-reading to the same degree as it's speedometer. If you keep your bike for plenty of miles you'll make up the cost of the replacement drive & have an accurate(ish) speedo. Seems worth doing to me.

Ade

 

[stephenenglish]

21 inch front wheel

My speedo matched up with the GPS reading after I fitted a 21 inch front wheel to my R1150GS ADV. The hub and speedo drive was original, just a bigger spoked up 21 inch rim from an R100GS.

 

[Dellis]

GPS Accuracy

I measured both my Quest and my Street Pilot on the M 6 Toll.

Set the unit to read in km then set the cruise control so that the GPS read 120 kmh (i.e. 2km per minute) then measured the accuracy over 4 km using the numbered post at the side of the motorway which are 100m apart.
Set up like this the 4 km should take 2 minutes and both units were within a second of this so I place my trust in the GPS speedo. I originally went to these lengths as the speedo in my previous car showed 90mph to the GPS's 80mph.

Dave

 

[Hay Ewe]

If you are that worried about the speedo, get a trailtech endurance computre. Its just a glorified bycycle one but proper for motorbikes.

I set it up and calibrated it on 5km zone and now over 5000 meters it reads 4985. Close enough for me.

I still use the big dial because its easier to read but use the trailtech for measuring tracks to turn points and such

http://www.trailtech.net/trailtech_computer_instructions.htm

see how you go

Hay Ewe