place your bets!

[darrsi]

[quote author=darrsi link=topic=22662.msg261685#msg261685 date=1496148625]
[quote author=Bretty link=topic=22662.msg261670#msg261670 date=1496137286]
Well honestly, I didn't go that quick...

141mph on the speedo -  129mph on the satnav with more to go.

...On the first day, I found unless I tucked in my arms and knees and got my head right down behind my double bubble windscreen, the bike was oscillating like mad from 120mph to 130mph!!!... and if I sat up under braking it got worse!!!  :eek :eek

Previously I remember the bike being more stable, although that had been with a top box and panniers and prior to replacing the head bearings and servicing the forks. The steering is now really light and maybe the fork service changed the geometry a little?! who knows..? I'm also a bit heavier these days?!

So the following morning I did a tyre pressure check and put a little more in front and rear to get 38/42. It made it a bit better to ride so I decided to power through and found I could reduce the oscillation a little if I put in a slight steering input.

So the results...

When I tucked in, I got the needle past 140mph on the speedo and it was still pulling!!... However I looked down at the TomTom and that was showing just 129mph. This was all fast enough for me and not a speed I wanted to sustain, so I backed off. I would say on a sustained run the bike would hit an 'actual'/satnav speed of 135mph.

Anyway, do i get a prize for saying 140mph? 
[/quote]

Err - I said  Silver = 141mph which was exacty right to the spedo
[/quote]


Damn and blast, so you did  :lol

[YamFazFan]

Is a sat nav more reliable than a speedo though?

I reckon it is.

I've read before that it is against laws/regulations for speedos to read less than the actual speed and therefore manufacturers 'play it safe'.

When my car speedo reads 30mph the sat-nav reads 28mph.

At 40 on the speedo it is 37mph on the sat-nav.

At 70 on the speedo it is 65mph on the sat-nav.

[darrsi]

[quote author=darrsi link=topic=22662.msg261685#msg261685 date=1496148625]
Is a sat nav more reliable than a speedo though?

I reckon it is.

I've read before that it is against laws/regulations for speedos to read less than the actual speed and therefore manufacturers 'play it safe'.

When my car speedo reads 30mph the sat-nav reads 28mph.

At 40 on the speedo it is 37mph.

At 70 on the speedo it is 65mph.
[/quote]


On that way of thinking though if you get nicked for speeding how do you defend yourself correctly?
You can't really argue the fact that your speedo is technically out of calibration otherwise you'd probably get nicked for that as well?

[darrsi]

[quote author=darrsi link=topic=22662.msg261685#msg261685 date=1496148625]
Is a sat nav more reliable than a speedo though?

I reckon it is.

I've read before that it is against laws/regulations for speedos to read less than the actual speed and therefore manufacturers 'play it safe'.

When my car speedo reads 30mph the sat-nav reads 28mph.

At 40 on the speedo it is 37mph on the sat-nav.

At 70 on the speedo it is 65mph on the sat-nav.
[/quote]


Just been having a look about and sure enough it mentions everywhere that manufacturers deliberately alter the speedo by "approximately" 8% to allow for certain things, ie: tyre wear, using tyres that started with quite high tread, which would eventually result in the wheel spinning quicker when just above the legal limit as the reading would change from when the tyre was new.
It's done to keep you under the limit by default because of the percentage discrepancy.


So on those maths, we should be getting 150mph, at a push, if the bike was new. I'd imagine that ship has sailed now, due to the age of them though, and wear and tear.

[fazersharp]

[quote author=YamFazFan link=topic=22662.msg261703#msg261703 date=1496171928]
[quote author=darrsi link=topic=22662.msg261685#msg261685 date=1496148625]
Is a sat nav more reliable than a speedo though?

I reckon it is.

I've read before that it is against laws/regulations for speedos to read less than the actual speed and therefore manufacturers 'play it safe'.

When my car speedo reads 30mph the sat-nav reads 28mph.

At 40 on the speedo it is 37mph on the sat-nav.

At 70 on the speedo it is 65mph on the sat-nav.
[/quote]


Just been having a look about and sure enough it mentions everywhere that manufacturers deliberately alter the speedo by "approximately" 8% to allow for certain things, ie: tyre wear, using tyres that started with quite high tread, which would eventually result in the wheel spinning quicker when just above the legal limit as the reading would change from when the tyre was new.
It's done to keep you under the limit by default because of the percentage discrepancy.


So on those maths, we should be getting 150mph, at a push, if the bike was new. I'd imagine that ship has sailed now, due to the age of them though, and wear and tear.
[/quote]
So David Ike is right when he says we are all living in an altered reality, what else is not real.

[BBROWN1664]

OK.

The law is that speedos are allowed to over read but are not allowed to under read. The maximum over read allowed is 10%. Speedos can never be 100% accurate.

On a car its easy to see why. A brand new tyre on the car has around 8mm of tread. A worn out one has 1.6mm. The difference in the rolling distance of the two is about 2%. This means physically travelling next to each other, two identical new cars with the new and worn out tyres will show different speeds of about 2%. Add in other factors like going round corners which makes one wheel turn faster than the other and it gets very confusing.

Now look at bikes. Which point on the tyre will the speed be accurate. When you are totally upright going in a straight line, or leant over going round a bend where you reduce the rolling radius even more?

Sat navs are more accurate but only in a straight line, on level ground, at a constant speed. Change any of the points here and the SATNAV is play catchup as it only calculates your speed between two points and assumes you are going at a steady speed in a straight line etc.

[fazersharp]

OK.

The law is that speedos are allowed to over read but are not allowed to under read. The maximum over read allowed is 10%. Speedos can never be 100% accurate.

On a car its easy to see why. A brand new tyre on the car has around 8mm of tread. A worn out one has 1.6mm. The difference in the rolling distance of the two is about 2%. This means physically travelling next to each other, two identical new cars with the new and worn out tyres will show different speeds of about 2%. Add in other factors like going round corners which makes one wheel turn faster than the other and it gets very confusing.

Now look at bikes. Which point on the tyre will the speed be accurate. When you are totally upright going in a straight line, or leant over going round a bend where you reduce the rolling radius even more?

Sat navs are more accurate but only in a straight line, on level ground, at a constant speed. Change any of the points here and the SATNAV is play catchup as it only calculates your speed between two points and assumes you are going at a steady speed in a straight line etc.

So how does all that effect the mileage read out - total have I actually done more or less miles than when my clock says

[darrsi]

[quote author=BBROWN1664 link=topic=22662.msg261720#msg261720 date=1496220691]
OK.

The law is that speedos are allowed to over read but are not allowed to under read. The maximum over read allowed is 10%. Speedos can never be 100% accurate.

On a car its easy to see why. A brand new tyre on the car has around 8mm of tread. A worn out one has 1.6mm. The difference in the rolling distance of the two is about 2%. This means physically travelling next to each other, two identical new cars with the new and worn out tyres will show different speeds of about 2%. Add in other factors like going round corners which makes one wheel turn faster than the other and it gets very confusing.

Now look at bikes. Which point on the tyre will the speed be accurate. When you are totally upright going in a straight line, or leant over going round a bend where you reduce the rolling radius even more?

Sat navs are more accurate but only in a straight line, on level ground, at a constant speed. Change any of the points here and the SATNAV is play catchup as it only calculates your speed between two points and assumes you are going at a steady speed in a straight line etc.

So how does all that effect the mileage read out - total have I actually done more or less miles than when my clock says
[/quote]


You've only actually done 100 miles in 19 years  :lol

[darrsi]

[quote author=darrsi link=topic=22662.msg261713#msg261713 date=1496205176]
[quote author=YamFazFan link=topic=22662.msg261703#msg261703 date=1496171928]
[quote author=darrsi link=topic=22662.msg261685#msg261685 date=1496148625]
Is a sat nav more reliable than a speedo though?

I reckon it is.

I've read before that it is against laws/regulations for speedos to read less than the actual speed and therefore manufacturers 'play it safe'.

When my car speedo reads 30mph the sat-nav reads 28mph.

At 40 on the speedo it is 37mph on the sat-nav.

At 70 on the speedo it is 65mph on the sat-nav.
[/quote]


Just been having a look about and sure enough it mentions everywhere that manufacturers deliberately alter the speedo by "approximately" 8% to allow for certain things, ie: tyre wear, using tyres that started with quite high tread, which would eventually result in the wheel spinning quicker when just above the legal limit as the reading would change from when the tyre was new.
It's done to keep you under the limit by default because of the percentage discrepancy.


So on those maths, we should be getting 150mph, at a push, if the bike was new. I'd imagine that ship has sailed now, due to the age of them though, and wear and tear.
[/quote]
So David Ike is right when he says we are all living in an altered reality, what else is not real.
[/quote]


No, he's just a nutter!

[BBROWN1664]

So how does all that effect the mileage read out - total have I actually done more or less miles than when my clock says

In reality, you have probably done 5-10% less than shown in the odometer. The odo gets its feed from the speedo.

[Bretty]

So what should the service interval be then?!  :\ :\

[darrsi]

So what should the service interval be then?!  :\ :\

For what?

[BBROWN1664]

So what should the service interval be then?!  :\ :\

As far as everyone cares, the odometer is correct and servicing is based on the reading there :pokefun . Reality is a bit different as most bikers don't do manufacturer mileage based servicing, they do it more often so the odo reading is pointless.

[fazersharp]

[quote author=fazersharp link=topic=22662.msg261723#msg261723 date=1496222711]
So how does all that effect the mileage read out - total have I actually done more or less miles than when my clock says

In reality, you have probably done 5-10% less than shown in the odometer. The odo gets its feed from the speedo.
[/quote]
Great - I dont do enough and now your telling me I have done even less !

[Bretty]

So what should the service interval be then?!  :\ :\

That was a silly irrelevant joke and reference to the fact if the speedo is out 10%, you might be doing a 3000mile service, when you had only done 2700. 


Anyway, I service my motorbike every 15,000 miles whether it needs it or not! :-p