Speedo Readings

[webbyc]

So how accurate are Ducati clocks?

To give some examples - riding down to the ferry I kept a steady 90 indicated - Robin behind me on a Busa said that he never showed under a ton (now I know that we shouldn't be doing these speeds but it was early and we were chasing a ferry - no excuse though).

Another example - following an SP2 and Gixxer750 in Germany, both of them had an indicated 160, whilst my 996R never indicated more than 145.

So who is right? I have heard that Suzuki clocks do overread.

[dickieducati]

the clocks on my 999s overread by about 8% i would guess other ducati's are roughly the same.

[m1keyp]

I have a sat nav mount for trips to Europe and the speedo v the sat nav is scary.

The speedo over reads badly (2002 748)

If time allows I will do a 30 50 70 100 speedo v sat nav check this weekend and let you know

Mike

[rockhopper]

I dont think speedos are allowed to under read - all the ones i have tested with my GPS over read, it usually gets worse the faster you go.

[Clippy]

Mine read 90 when the digital speedo on the new Merc following me read 81/82 all the way along a 15 mile run.

The most accurate speedo I've found on a bike was on the RSV Mille - that was reading 143 when my mates SP1 was telling him 165 and we were acctually doing about 140 (on a closed road/autobahn/racetrack of course!). No wonder Honda riders have a few tall stories to tell!

Giles

[baylissboy]

The speedo on my Foggy rep under red by 10MPH,when compairing it to other bikes on a ride out!

[Mr_S]

When I first picked up my 748 I didn't believe the speedo, thinking it was reading way too high (20-30mph)

I did a GPS comparison on a straight (and flat) piece of road, and the result was consistent in that the speedo read about 10% over, all the way up.

Rockhopper's right that they can't under read, only over read as EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers.

These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied.

The requirements are also that the indicated speed must never be less than the true speed.

[rockhopper]

Of course if you change tyre sizes then the speedo calibration will be messed up as well unless you keep the same rolling radius.

[weeveetwin]

I guess this also means that when your clock says your bike's covered 10,000mls, its really only covered about 9,000!

[AK]

Webby - this could account for the day you & Alan came back from Kent together - and he was having to consistently travel at 100 - 110 to ride with you (not too much fun on a monster on the motorway for quite a few miles, and his arms had been stretched like a monkeys by the time he got home) - you said you hadnt been over 90 that day.
Alans Lawson consistently reads 17% less than the speed he is actually doing.

We usually use my bike as the 'speed guide' when each creation gets put on the road.

C

[Steve M]

Originally posted by weeveetwin
I guess this also means that when your clock says your bike's covered 10,000mls, its really only covered about 9,000!

Good point this, as more miles = lower value and sooner servicing (if you do it by miles rather than anually) Though the milometer and speedometer are not necessarily both reading wrong or by the same amount.

[webbyc]

I'm baffled by this - the only thing I've done from standard is to raise the rear sprocket to 38 instead of 36. Would that make any difference?

Or is just that rice burner clocks way overread to make their riders feel better?:lol:

[Edited on 24-6-2004 by webbyc]

[MJS]

Originally posted by STEVE M
Originally posted by weeveetwin
I guess this also means that when your clock says your bike's covered 10,000mls, its really only covered about 9,000!

Good point this, as more miles = lower value and sooner servicing (if you do it by miles rather than anually) Though the milometer and speedometer are not necessarily both reading wrong or by the same amount.

I've done the same journed from Northampton to Camberley, around 90 miles, and clocked a good mile and half difference between my 996 and zx6r - can't remember which one clocked which, but I was surprised by the difference at the time.

[Edited on 24-6-2004 by Urban996]

[mike916]

Cant make a differance the speedo dries on the front whek init



Originally posted by webbyc
I'm baffled by this - the only thing I've done from standard is to raise the rear sprocket to 38 instead of 36. Would that make any difference?

Or is just that rice burner clocks way overread to make their riders feel better?:lol:

[Edited on 24-6-2004 by webbyc] :sing::sing::sing::sing:

[Ray]

On a 748/916/99* the speedo is driven by the front wheel so gearing changes don't affect the speedo. Most if not all monsters and most other Ducs do as well. Don't know where these new fangles Multistranglers or 999 types take the speedo feed from.
Using the front wheel pickup there will be slight differences between tyre makes and as the tyre wears due to differences in the circumference/rolling diameter.

Jap bikes tend to use a speedo drive from the gearbox so gearing changes do affect speed readings.

As for the over reading causing more services, quicker drop invalue etc isn' that why some helpful individuals offer "mileage correction":lol:

Ray

[Garibaldi]

Bike magazine reports speedo accuracy in its tests. July's test of nthe 749S, 999, RSV-R and Benelli Tornado Tre were as follows:

749S 70mph ind = 66 real , 100mph ind = 95 real
999 70mph ind = 65 real, 100 mph ind = 92 real
RSV-R 70mph ind = 66 real, 100mph ind = 93 real
Benelli 70mph ind = 63 real, 100mph ind = 90 real

So indicated is typically 5-7% lower than real on the dukes and up to 10% lower on the Benelli.

Don't have any Jap bikes to compare against but I'll keep 'em peeled next month.

[Steve M]

I've done the same journed from Northampton to Camberley, around 90 miles, and clocked a good mile and half difference between my 996 and zx6r - can't remember which one clocked which, but I was surprised by the difference at the time.

[Edited on 24-6-2004 by Urban996]

same journey to north Wales done many times - my wife's VW Polo read 75 miles, my bike always reads 71 miles.
Wonder what her new car would say.

[Shazaam!]

The 998 and 748 hub speedometer gears are the same. The speedometer error for a 998 with a 70-section was measured against a GPS standard by one owner to be:

40 998 = 37 GPS
50 998 = 46 GPS
60 998 = 56 GPS
70 998 = 65 GPS
80 998 = 73 GPS
90 998 = 82 GPS
100 998 = 89 GPS

If you switch to a 60-section tire (that comes standard on a 748,) the circumference is smaller than a 70, so the wheel sees more revolutions per mile and the speedometer reads higher. Consequently, the speedometer reads closer to the true speed (still low,) and it’s more accurate on a bike with a 60-section tire.

[BDG]

I ran a tuned Blackbird at Bruntingthorpe and the speedo would show 205 to 210mph but through the timing lights the best was a genuine 186mph.

Same story with Kwak ZX9R, ZZR1100 and even a Honda VFR800 indicated nearly 170mph! which was a true 156mph.

All the speedo's that day were roughly 10% over.

Just to compound matters i had an ST4 that rarely showed more than 130 when other people would be showing upto 160mph. Speedo's on ST4S and 996SPS always seem to read less than friends bikes so maybe Ducati speedo tell fewer lies.

[rockhopper]

If anyone is in the Midlands and wants to borrow my GPS so they can check their speedo they are more than welcome.

[bostrom998]

Ducati are much more honest about ALL their figures aren't they?

Certainly their power outputs are measured much more honestly than some Jap manufacturers, indeed they used to quote rear wheel figures rather than crank.....?