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From: Thomas on 22 Jul 2010 21:49 On Jul 22, 2:27 pm, Mark Olson <ols...(a)tiny.invalid> wrote: > The Older Gentleman wrote: > > We hear a lot about speedo error, but not about odometer error, yet it > > affects one's perception of fuel consumption, for one thing. > > > I suppose nobody's ever really been arsed enough to measure it. > > Oh? > > There used to be a 10 mile stretch of road marked as an odometer > calibration route not far from me, the signage is not there anymore > but the mileposts are still where they have been for many years. > > Typically I find odometers to be within a percent or two, it's > quite rare to find one off by more than that. On the other hand, > speedometers are usually much more optimistic, I've seen them > read as much as 11% over true. Obviously this is deliberate, as > the odometer calibration is nearly always perfect yet the speedo > never is, and IME speedos never under-read unless they're broken. There are still a few "Mile 0" "Mile 1", etc, markers around that I see. IME, odos are usually pretty close, too. The street wisdom on speedo error is that manufacturers don't want to be liable for speeding tickets (or some such) and deliberately set speedos to over-read. Dunno if it's true, but I wouldn't doubt it. My Hondas are around 7% off.
From: Mark Olson on 22 Jul 2010 23:08 Thomas wrote: > On Jul 22, 2:27 pm, Mark Olson <ols...(a)tiny.invalid> wrote: >> The Older Gentleman wrote: >>> We hear a lot about speedo error, but not about odometer error, yet it >>> affects one's perception of fuel consumption, for one thing. >>> I suppose nobody's ever really been arsed enough to measure it. >> Oh? >> >> There used to be a 10 mile stretch of road marked as an odometer >> calibration route not far from me, the signage is not there anymore >> but the mileposts are still where they have been for many years. >> >> Typically I find odometers to be within a percent or two, it's >> quite rare to find one off by more than that. On the other hand, >> speedometers are usually much more optimistic, I've seen them >> read as much as 11% over true. Obviously this is deliberate, as >> the odometer calibration is nearly always perfect yet the speedo >> never is, and IME speedos never under-read unless they're broken. > > There are still a few "Mile 0" "Mile 1", etc, markers around that I > see. IME, odos are usually pretty close, too. > > The street wisdom on speedo error is that manufacturers don't want to > be liable for speeding tickets (or some such) and deliberately set > speedos to over-read. Dunno if it's true, but I wouldn't doubt it. My > Hondas are around 7% off. You're right about speedo error. You have to be careful about assuming that mile markers are exactly a mile apart. I know of two locations where they are off considerably over a significant number of miles. You'd think the highway dept folks would not do this, but think about it- when a road that is hundreds of miles long through a state has a new piece constructed nearby but not exactly following the previous route, they re-distribute the existing mileposts either farther apart or closer together over that new section, they don't rip up every single milepost starting at one border and replace them all the way across the state. I know this is the case on US 169 and on US 10 in two specific places in MN.
From: The Older Gentleman on 23 Jul 2010 07:40 Thomas <keensurf(a)gmail.com> wrote: > There are still a few "Mile 0" "Mile 1", etc, markers around that I > see. IME, odos are usually pretty close, too. > > The street wisdom on speedo error is that manufacturers don't want to > be liable for speeding tickets (or some such) and deliberately set > speedos to over-read. Dunno if it's true, but I wouldn't doubt it. My > Hondas are around 7% off. They do vary. I remember Yamaha RD350 and power-valve ones were tested by the magazines and turned out to be astonishingly accurate - like bang on at 60 and maybe 1 mile an hour out at 70. ShiteOldGuzzi ones varied, as you'd expect. A friend's V50 actually under-read badly: showed 60 at 70 (according to Plod) while my Spada, as, er, kindly calibrated by French Plod, was showing 85mph at a speed-trapped 135kph. -- BMW K1100LT Ducati 750SS Triumph Street Triple Honda CB400F Suzuki TS250 Suzuki GN250 chateaudotmurrayatidnetdotcom Nothing damages a machine more than an ignoramus with a manual, a can-do attitude and a set of cheap tools
From: The Older Gentleman on 23 Jul 2010 07:40 boots <boots(a)despammed.com> wrote: > On Thu, 22 Jul 2010 18:49:30 -0700 (PDT) in uk.rec.motorcycles, Thomas > says: > > >The street wisdom on speedo error is that manufacturers don't want to > >be liable for speeding tickets (or some such) and deliberately set > >speedos to over-read. Dunno if it's true, but I wouldn't doubt it. My > >Hondas are around 7% off. > > Here at least it's a requirement that a speedo does not under read, of > course that's certain when it leaves the factory. More than that. It's also a legal requirement that they have kph markings as well as mph, and my Ducati just has mph. There was a bit of a stink in the press a few years ago, because some over-zealous MOT testers were refusing to issue MOT certificates to Ducatis so equipped. -- BMW K1100LT Ducati 750SS Triumph Street Triple Honda CB400F Suzuki TS250 Suzuki GN250 chateaudotmurrayatidnetdotcom Nothing damages a machine more than an ignoramus with a manual, a can-do attitude and a set of cheap tools
From: The Older Gentleman on 23 Jul 2010 10:06
boots <boots(a)despammed.com> wrote: > On Fri, 23 Jul 2010 12:40:12 +0100 in uk.rec.motorcycles, The Older > Gentleman says: > > >boots <boots(a)despammed.com> wrote: > > > > > >More than that. It's also a legal requirement that they have kph > >markings as well as mph, and my Ducati just has mph. > > Presumably to placate the johnny foreigners in the EU? > > >There was a bit of a stink in the press a few years ago, because some > >over-zealous MOT testers were refusing to issue MOT certificates to > >Ducatis so equipped. > > Did it fail on that's what it left the factory with test? Well, mine has never been failed, but apparently the fact that "it came like that" is immaterial. Under EU rules, all mph speedos made since (whatever date, but quite a few years back) should also have kph graduations, and Ducati sort of forgot :-)) -- BMW K1100LT Ducati 750SS Triumph Street Triple Honda CB400F Suzuki TS250 Suzuki GN250 chateaudotmurrayatidnetdotcom Nothing damages a machine more than an ignoramus with a manual, a can-do attitude and a set of cheap tools |