My speedometer is 2 MPH optimistic...

[sonicsix]

I always check my speedometers against 2 different GPS units to see how accurate they are. My 2012 Kymco Like 200i scooter is dead on at every speed, but the Spyder is 2 MPH optimistic. Not bad, but it is good info to know. So I can be doing 60 MPH in a 55 MPH zone and I feel like I am speeding along, when I am really just doing 58 MPH and the police won't give me a second look.

 

[flamingobabe]

most motorcyles are a bit Optimistic...my husbands Valk is about 5 mph....my Spyder that I sold was at or 1 off...we'll see what the new will be...maybe next weekend

 

[TuckMiddle]

My RT is2 mph over. I've even checked it with 2 GPSs at once. So when I went screaming by a county enforcer today at 58 as he sat along the. 2 lane, I was in great shape.
I looked in the mirrors and he pulled out just behind me with lights flashing. He must have been at 100 when he went by me. I almost gave him the finger, but chickened out.
Guess he realized his shift was over or the local superstate had free left over donuts at 4:00
Great ride today in 50s and Ron's new bar is still workin great

 

[gnirtsnod]

I always check my speedometers against 2 different GPS units to see how accurate they are. My 2012 Kymco Like 200i scooter is dead on at every speed, but the Spyder is 2 MPH optimistic. Not bad, but it is good info to know. So I can be doing 60 MPH in a 55 MPH zone and I feel like I am speeding along, when I am really just doing 58 MPH and the police won't give me a second look.

Yeah, Honda was sued over this issue because it added miles to the odometer and ...you guessed it, the warranty ran out sooner. They were 3% off.

 

[MrLooney]

SPEEDOMETER 2+ over

I always check my speedometers against 2 different GPS units to see how accurate they are. My 2012 Kymco Like 200i scooter is dead on at every speed, but the Spyder is 2 MPH optimistic. Not bad, but it is good info to know. So I can be doing 60 MPH in a 55 MPH zone and I feel like I am speeding along, when I am really just doing 58 MPH and the police won't give me a second look.

When I bought my 2011 RS~S :spyder2: in Dec 2012 from a great guy near Park City Utah and rode it on a 5,000 mile ride to Dallas Fort Worth, then to Cal (+10) and up to Oregon (+5) I noticed my SPEEDO was faster than it should have been. Case in point, a local Texas (+5) Constable clocked me at 68 in a 60 zone (Let go with a warrning only). Come to find out Texas and many other states are now allowing ONLY 5 MPH over posted speed.

YES, this is a Warrenty issue BUT I don't mind loosing a few miles on the Speedo for the safety of getting a FINE of hundres of $ $ $ for each infraction. Even still if we all just roll back on the grip and cruise the sunny highways enjoying the scenery, we can all be happy.

Dan
P.S. Missing my :f_spider:

 

[SllimG]

Interesting. Mine is exactly 2 miles an hour fast too.

 

[NancysToy]

As was said, most motorcycles are a bit optimistic. Part of the reason is that they are calibrated for the unladen tire diameter, but when the vehicle sits on the ground the effective diameter is less (rolling diameter), so the vehicle doesn't roll as far per revolution. The Spyder isn't too bad. The average for the older BMWs was about 12% optimistic. More vhicles, including cars, are optimistic than otherwise. Only large commercial vehicles and law enforcement vehicles have standards for speedometer accuracy, as far as I know

 

[Wiredux]

Mine is 2 behind but I am ok with that.

 

[harrypottar]

I ride with mine in kilometer mode, helps in keeping me young to see how fast I can ride still.

Harry

 

[bhfromme]

My 2011 reads 2 mph over actual speed also. No big deal there but what dtives me nuts is the temp reads anywhere from 6 to 8 degrees warmer than the actual outdoor ambient temperature. Is everyone else having that problem?

Bill

 

[missouriboy]

As was said, most motorcycles are a bit optimistic. Part of the reason is that they are calibrated for the unladen tire diameter, but when the vehicle sits on the ground the effective diameter is less (rolling diameter), so the vehicle doesn't roll as far per revolution. The Spyder isn't too bad. The average for the older BMWs was about 12% optimistic. More vhicles, including cars, are optimistic than otherwise. Only large commercial vehicles and law enforcement vehicles have standards for speedometer accuracy, as far as I know

I've always wondered about this (and the effect of underinflation, too). The theory here is that the inches traveled per wheel revolution varies with these factors. Right? But... if you put a tape measure around any tire tread, you get X number of inches. Now, tread material is pretty tough stuff, and it seems to me it would never vary in length of circumference no matter what. If a tire is low and bulging, that of course gives it a longer footprint, but it doesn't alter the number of inches of hard-rubber tread-length around the tire. Does it? My feeble mind tells me "No, it cannot alter the physical length of the tread." Yet, it apparently does alter the distance traveled per revolution. Can someone explain this? :dontknow:

My Spyder is 2mph optimistic also, according to my GPS.

 

[Chupaca]

I see..!!

Well the masses have spoken and the results are in...2... I actually have no idea about my own speedo seldom have my gps on but will have to check it out. Is the speed read from the wheel or the tranny..? If the wheel, at what speed does the wheel height max out..? :dontknow:

 

[docdoru]

With a rear tire 225/55/15 the display speed in now identical with the GPS speed.:thumbup:
http://www.spyderlovers.com/forums/showthread.php?23582-Another-myth-debunked

 

[SpyRyd]

My RT is2 mph over. I've even checked it with 2 GPSs at once. So when I went screaming by a county enforcer today at 58 as he sat along the. 2 lane, I was in great shape.
I looked in the mirrors and he pulled out just behind me with lights flashing. He must have been at 100 when he went by me. I almost gave him the finger, but chickened out.
Guess he realized his shift was over or the local superstate had free left over donuts at 4:00
Great ride today in 50s and Ron's new bar is still workin great

...or maybe he could have been responding to a situation in which a fellow citizen's life was in jeopardy and for whom he was willing to put his life on the line...just saying! Not sure I understand your need to give him the finger or your demeaning comment about the possible reason for him to pull out behind you with lights flashing and going by you at 100. Just wish all citizens would appreciate the really dangerous job the police do for us. Again, just saying.

 

[Bob Denman]

I've seen a consistent 1 mph high reading at 40 mph...
So I'm also falling within that 2 mph window that most of you are seeing. :thumbup:
No big deal...

 

[NancysToy]

I've always wondered about this (and the effect of underinflation, too). The theory here is that the inches traveled per wheel revolution varies with these factors. Right? But... if you put a tape measure around any tire tread, you get X number of inches. Now, tread material is pretty tough stuff, and it seems to me it would never vary in length of circumference no matter what. If a tire is low and bulging, that of course gives it a longer footprint, but it doesn't alter the number of inches of hard-rubber tread-length around the tire. Does it? My feeble mind tells me "No, it cannot alter the physical length of the tread." Yet, it apparently does alter the distance traveled per revolution. Can someone explain this? :dontknow:

My Spyder is 2mph optimistic also, according to my GPS.

I can understand your confusion, but it has nothing to do with the actual circumference, since the entire circumference is not in contact with the ground at one time. The best way to verify this (and determine the rolling diameter) is to mark the tire at the center where it contacts the ground, and mark the ground at this point. Then roll the vehicle exactly one tire revolution, mark the ground again, and measure the distance between the marks. You will find that it is less than the circumference measured around the tire. The reason is that the effective radius of the loaded vehicle is less. 2*radius*pi=circumference. The closer to the ground the axle is, the less the radius, so the less the effective circumference. Class dismissed.

 

[2Paw]

My Burgman is 10% off at every speed, 50 = 45, 60 = 54 and Suzuki designed it that way we were always told. People complained about having to do the math in their heads all the time but, over time it becomes automatic to compensate. I was once involved in a "discussion" with a fellow that was concerned he might be rear ended in heavy traffic because of it. Couldn't convince him that if he was not going with the flow that he was the problem not the mechanicl device on the machine. I think he may have quit riding all together because he couldn't wrap his head around that or maybe he was rear ended out on the freeway, all I know is I haven't seen him around for quite awhile.

 

[bobnaquin]

Mine is 2 MPH also. It would be very easy to allow this to be user adjustable so that we could make it read correctly. I had that feature on a boat and boats are notoriously bad when it come to displaying speed on a speedometer.

But my gas mileage is 1 mpg gallon higher than it would be if correct, and I need all of the range that I can get.

 

[Bob Denman]

I can understand your confusion, but it has nothing to do with the actual circumference, since the entire circumference is not in contact with the ground at one time. The best way to verify this (and determine the rolling diameter) is to mark the tire at the center where it contacts the ground, and mark the ground at this point. Then roll the vehicle exactly one tire revolution, mark the ground again, and measure the distance between the marks. You will find that it is less than the circumference measured around the tire. The reason is that the effective radius of the loaded vehicle is less. 2*radius*pi=circumference. The closer to the ground the axle is, the less the radius, so the less the effective circumference. Class dismissed.

:shocked:

 

[Can-Am Poogs]

Why would you think your GPS speed is accurate.

Could just be me, but why give so much credit to your GPS to be 100 % accurate. I would say it is reliable, but I wouldn't say it is 100% accurate. I have tested the accuracy of speedometers for years. The best way is to use a hand held radar gun that has itself been tested for accuracy. When the radar gun is in the moving vehicle in stationary mode, the reflected beam from stationary objects and the terrain will display a reading on the radar gun. Since these objects have a speed of 0 kmph or mph, and you are the only thing moving then this is your speed. The speed on the radar is compared to the speed on the vehicle speedometer. This should be done at a speed below 50km/h, a speed between 50 and 100 km/h, and a speed above 100 km/h. A certified radar gun has an error plus/minus 1 km/h. Which is a refined way of saying 2 km/h. Any speedometer in this range of error is a certified speedometer. Sorry for the metric. I can't speak to how GPS gets a speed reading. RADAR is instantaneous speed using waves that travel at the speed of light. Not sure if GPS gives a reading based on average speed based on velocity over distance, and makes instantaneous calculations based on average speed over terrain. This could account for the different readings than speedometer.