Why are speedos inaccurate?

[Kickstart]

[sickpup]

I ask as last time I saw a COPY it stated accuracy within 10% not stating over or under reading.

[zx636]

How many of you guys constantly check your speed using the speedo.

I find i have a feel for how fast the bike is going and can more or less tell. Hard to explain but you feel the 30 40 and 50 speeds.

[Kickstart]

[Kickstart]

Hi

Bit more of a search round and it seems we are both wrong.

The "Road Vehicles (Construction & Use) Regulations 1986" have now been amended by EC directives.

Found this that puts it into English.

Found this that has the revisions.

[Rookie]

That makes sense, it's probably government enforced, as then people can't use the excuse that their speedo was out, so they didn't know they were speeding. The other way though, and if they are caught speeding, it will be of a lower speed than they were caught doing anyway.

[lurker]

[lurker]

oops didnt read above replys b4 posting

[spakmitten]

oh dear

cospirasy theroies debunked to the MAX

https://www.badastronomy.com/

[sickpup]

[Kickstart]

Hi

Maybe I am cynical, but the speedo is one of the cheapest devices to "tune" to make a bike seem faster.

How many manufacturers are going to spend large amounts of money making the speedo more accurate when the only effect is to make people think there bikes are slower.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Villers]

My mate has been playing round with his GPS which can now read accelleration in feet per second etc and he done a 102 on his ZX6r and the GPS recorded 108. Does this make his bike illegal, innacurate or is the GPS innacurate?
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RS125 > CBR6 > SV650S > ZX636R > GSX1300RZ Hayabusa > 06 RSVR Mille > SV1000S > Street Triple 765 RS

[Kickstart]

Hi

Depends how many satellites it was reading at that moment. They can be fairly inaccurate and jump around.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[ali-b]

[pipnet11]

Ah but at least if you stay at a constant speed your speedos stay a constant speed. Old Smiths speedos, and even the new Enfield speedos will wobble about all over the place. They seem to simply estimate what speed you are going!
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I love the girls that do, I hate the girls that dont, I hate the girls who say they will and then they say they wont, but the girl I like most of all and I think youll say Im right, is the girl who says she never has but looks as though she might. - Max Bygraves

[freestyler_onli]

I hate innaccurate speedos. It looks so much bigger when you wear bermuda shorts..............

[kal9001]

Can you get a GPS speedo...i dont want any of the map bollox just a small unit that JUST READS SPEED on a digital output...then you know how fast your going...would be cool...
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Anyone stupid enough to think we will drag a load of wooden horses full of soldiers into our city is certanley stupid enough to drag all of ours into theirs!

[Jack_Cheese]

[bigdazz]

I think manufacturers take the cautios approach if you got nicked for speeding on a new bike for say 5 mph over the limit and found the speedo to be underreading you would have a good case for compensation from the manufacturers, so they calibrate them to be slightly over to allow for this.
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1998 Honda Fireblade
1990 Enfield Bullet 500
1982 Suzuki Katana 750

[Jack_Cheese]

To be honest, i think having speed limits strictly enforced is a bad idea. If people are looking at their speedos, it's a fairly safe bet that they're not looking at the road. The police round here don't really care about much, whilst riding at the speed limit, a police car overtook me with no sirens or lights, and im sure thats against the law. Maybe the oracle could shed some light on that one.

Jack
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www.bikepics.com/members/jackcheese <--- NOW FOR SALE! 51 Plate Cagiva Planet 125
Quacker_boy: "Jack, you really are a dick!"

[marc_yorks]

buy a mille
the most accurate speedo's ever
was chasing my mate on his zx9r the other day,we were near enough level,his speedo was saying 165,mine 151
we were on private roads of course
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Don't make me blue

[kal9001]

i agree, takeing serious action for someone whos doing 35 in a 30 just cos hes not being osbessive about his speed, and constantley looking and jabbing the brakes on, wich im sure is annother major cause of accidents, oooocrap im 5mph above the speedlimit after that lil hill :jabbs brakes on: smash driver behind "WTF are you doing stoopid cunt!"
i have allwasy said speed limits shoul dbe a guide, and if people arent reponcible enough to take that on board and ride/drive to the conditions then thats their problem and then they get the book! but in places 80 is more then acceptable in a 60...and 60 is no more dangerous in 30 zones...as im sure alot of people will agree here its the road conditions that judge the speed, not the sily signs, i can be doing 30 in a 40 and still be an asshole...
it seems that the DVAL/DSA and the goventment/police are trying to eliminate all thaught from driveing...you WILL DO the limit, notunder or over, you WILL mindlessley follow road sighns even those that tell you to do 3MPH round the "bad" corner that a robin reliant could do 90 around!

people do seem to think less these days while driveing...people who just drive at 40 anywhere, cos they are too lazy to adjust their driving to the given limit...anddo40soitall averages out in the end or who NEVER indicate, or only do so after they are already half way into the corner...ifpeople just started to think more and PAY ATTENTION thenthere would be alot less accidents...

alsoifpeople just paid abitmore consideration to other people in any situation then our daily lives would be much better, and we would progress as a society...
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Anyone stupid enough to think we will drag a load of wooden horses full of soldiers into our city is certanley stupid enough to drag all of ours into theirs!

[Jamie_ducati]

mass production techniques and lack of regular calibration. Police vehicles have expensive and regularly calibrated speedos.

if you know where your "local mile" is (used by Police to double check) you can ride that mile at 60mph in exactly 60 seconds...
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Jamie
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Time for eDUCATIon