VTR Speedo accuracy

chrisk992003 · Post by **chrisk992003** » Wed Aug 13, 2003 9:57 am

I'm sure my speedo is under reading - travelling down the m4 everyone seems to be travelling at 90 and occasionally 100. I do the same journey in my car and things are a lot slower. I reckon I'm reading about +10mph

Anyone else have this problem and can you get it adjusted ?

Fireman on a Storm · Post by **Fireman on a Storm** » Wed Aug 13, 2003 10:45 pm

Your speedo may read under if you have a 15 tooth front sprocket instead of a 16 standard one. But only by a couple of mph.
Have you got the correct size rear tyre?

You can get a different reading between a brand new tyre and a very worn out one.

To check your speedo against the car or another bike travel a set distance in both and check distance traveledon the trip meter.
If your speedo is under reading you will have covered a greater distance than one reading corectly. The only 100% accurate speedos are in traffic police cars.

A freind has a 15t on his TLs and over 100 miles his bike reads 103 miles compared to my standard 16t bike

delmeekc · Post by **delmeekc** » Wed Aug 13, 2003 10:58 pm

I use a GPS to set all my speedo's up, see if you can borrow one from somebody, will be accurate to 0.01 mph.

Del.

Fireman on a Storm · Post by **Fireman on a Storm** » Thu Aug 14, 2003 8:35 am

Not up with this high tech stuff how do you do it with GPS

chrisk992003 · Post by **chrisk992003** » Thu Aug 14, 2003 10:11 am

Del - I suppose that means you can adjust the speedo - I'm guessing a screw on the back ?

andy c · Post by **andy c** » Fri Aug 15, 2003 12:19 am

I check the accuracy on all new bikes and cars by following a truck on a fastish road all large trucks have a speed limiter fitted accurate to 2% much more accurate than a speedo 10% and should be set to 56 mph max most vehicles ive driven / riden read about 60mph when following its not spot on but it gives you a good idea

t00lkit · Post by **t00lkit** » Fri Aug 15, 2003 4:35 pm

May sound obviuos, but here goes..
How about getting a mate to drive down a section of Motorway/daul carriageway and agree a speed to drive/ride at. Say 70mph.
You can then see what you are reading and compare?
t00lkit

Stormin Ben · Post by **Stormin Ben** » Sat Aug 16, 2003 1:43 am

I normally ride down the motorway at a constant speed and time how long it takes to do 1 mile according to those little marker posts at the side.
Then with the aid of my trusty Mr Men calculator and using the equation Speed = Distance / Time I can work out my actual speed versus my indicated speed
Then I normally have a lie down coz my brain hurts!!

Ben

Stormtrooper · Post by **Stormtrooper** » Sat Aug 16, 2003 9:11 am

well how about looking for a plod with a speed gun & nail it past him whilst
looking at the speedo then when & or if he catches you you will know how correct the speedo is... of course this method can prove costly

im usually (A) to busy looking where im going or (B) hanging on for my life to bother to much if the speedo is plus or minus 10%
just ride it

philsmith · Post by **philsmith** » Sat Aug 16, 2003 10:58 am

Stormtrooper wrote: just ride it

I agree... Just get on & give it some...