Speedo accuracy and calibration.

[neptune8]

I know that most speedos exagerate the speed of the vehicle. In other words, the speed shown on the dial is greater than the actual speed of the vehicle. I am a bit odd, I know, but I try to stick to speed limits all the time. I passed through a village recently, which has a 30 limit. It also has a radar device that shows your speed. I know that the speedo on my CG125 is not accurate, and By comparing speeds with my daughters car, I worked out that when my speedo reads about 33, My speed will be a true 30. So I rode through said village at an indicated 33, and the radar said 27! My question is, does anyone know a cheap easy way to calibrate a speedo?
____________________
Enjoy yourself, its later than you think

[Commuter_Tim]

If you mean these dealios...
https://l7.alamy.com/zooms/f25226a0fd044b74877be847a9b23d30/traffic-speed-warning-indicator-by-the-road-with-a-car-exceeding-the-dnxby4.jpg
It is my understanding they are not required to be all that accurate. (awaits being corrected by Rog etc)
I can assert the one near me sure as shit hasn't been accurate since they installed it 6 years ago.

Also "Enter" Key Bro, learn to love it.
____________________
The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[BumpingUglys]

Those light up signs will be about as accurate as your speedo and/or your daughter's car i.e. not particularly.

I think the usual way to gauge actual speed without specialist kit is to use some kind of GPS. Though I imagine there's a certain degree of fallibility in a lot of those.
____________________
Ducati M695

[Billy Balthorpe]

[Kentol750]

These don't always catch a bike very well, (small frontal area). I've gone through at 17mph on bandit 600 showing 30, 29 on fazer 600. On a test a pupil saw 18 flash up (on sv650) and then 29 as examiner went through on deuville/nc700. Luckily he didn't ping it up to 40 and fail!
____________________
Some bikes.

[Billy Balthorpe]

[Kentol750]

If he'd not seen the 29 flash up he said he would've thought the gradient and throttle off had slowed him more than he thought....bit of test nerves....we'd been there a few times on our training! ( had a fail a few years back missed 30 sign and it flashed 37 in red!)
____________________
Some bikes.

[andyscooter]

I've made one flash at 99 more then once on a 125
____________________
gilera runner vxr200 (chavped)
if its spelt wrong its my fat fingers and daft auto correct on my tablet

[ThatDippyTwat]

There's on one my commute into work. It freak out I'm doing more than 30, but it still does that if I'm under 20, no matter car or bike.

If you're speedo says you are just under, then it won't be a problem, and you won't hold anyone up that's not hoofing it.
____________________
'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)

[Ste]

[yen_powell]

I've put those types of illuminating digital signs up and the manufacturer asked me what I wanted it to display at 30mph (they are adjustable). I said 32 so it would always over read.

I wouldn't take one of those as being correct at all.
____________________
Blackmail is a nasty word........but not as nasty as phlegm!
XT1200Z and a DR350 in bits

[ZebraDriver]

Try finding a government calibration site. They can be recognised by a yellow box mounted on a pole. Once you find one go past it as fast as you can, it will flash twice to acknowledge your participation in the scheme, remember to note your speedo reading at the second flash. Your speedo calibration certificate will arrive in the post a few days later.

Please be aware that the charge levied for using the system is quite high (the charge will be advised along with your calibration certificate)

They do operate a reward points scheme as well, if you collect enough points you get a pushbike

[talkToTheHat]

Just compare to a GPS speedo app on your phone or use a tomtom. Your speedo is likely at least 10% optimistic. This means you can have 90 on the clocks, feel like the fastest badass on the motorway and probably not make the threashold for a gubmint issue calibration certificate.
____________________
Bandit. does. everything.