My speedometer is 2 MPH optimistic...

[ARtraveler]

I look at it as speeding ticket insurance. I usually ride at posted plus five maximum. I have never had an officer pull me over for speeding in AK. In the scheme of things, getting somewhere 2 mph slower, does not have much of an effect on my trip.

As an owner of a few Kawasaki's--most of them were 5 mph less than actual.

 

[NancysToy]

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.

You are right...radar is more accurate than a gps. GPS speeds can vary due to a couple of factors. First,, the accuracy of typical over-the-counter gps units is only about 15-25 feet. That relative inaccuracy in pinpointing the position can lead to errors in the speed calculation...but they usually cancel themselves out if you are traveling at highway speeds in open country with several satellites available. Second, a gps measures distances that are assumed to be horizontal. Steep hills cause you to travel farther than the gps thinks you do, so you can be moving faster than it calculates. Again, this effect is limited to the mountains and steep hills, and is relatively minor. By all means, check your speedo against radar or time it between mileposts if you can, but most gps units are quite accurate, and provide an excellent comparison.

BTW the gps calculates speed based on how far it senses you have moved in a certain time.

 

[Can-Am Poogs]

You are right...radar is more accurate than a gps. GPS speeds can vary due to a couple of factors. First,, the accuracy of typical over-the-counter gps units is only about 15-25 feet. That relative innacuray in pinpointing the position can lead to error s in the speed calculation...but they usually cancel themselves out if you are travelling at highway speeds in open country with several satellites available. Second, a gps measures distances that are assumed to be horizontal. Steep hills cause you to travel farther than the gps thinks you do, so you can be moving faster than it calculates. Again, this effect is limited to the mountains and steep hills, and is relatively minor. By all means, check your speedo against radar or time it between mileposts if you can, but most gps units are quite accurate, and provide an excellant comparison.

BTW the gps calculates speed based on how far it senses you have moved in a certain time.

Thanks for the response. Makes sense to me.

 

[jwmcclellan]

Just checked my speed today against the radar where I work, and I matched the speed shown exactly. 2012 RT Limited.

 

[Huddleston]

2013 Spyder RT-SE5 speedometer

My GPS reads 2 miles per hour less than the Digital Speedometer. So, at 55, I am going only 53 on the GPS. This means that the warranty will expire 3.6% earlier than it should. There has been litigation on other vehicles for the same issue. I had a Subaru that the warranty was extended by Subaru in settlement of a lawsuit. I am not advocating such for the Spyder, but I think everyone should be aware of the issue before your warranty expires. I purchased the extended warranty, so it is not an issue for me for quite a while.

 

[NancysToy]

My GPS reads 2 miles per hour less than the Digital Speedometer. So, at 55, I am going only 53 on the GPS. This means that the warranty will expire 3.6% earlier than it should. There has been litigation on other vehicles for the same issue. I had a Subaru that the warranty was extended by Subaru in settlement of a lawsuit. I am not advocating such for the Spyder, but I think everyone should be aware of the issue before your warranty expires. I purchased the extended warranty, so it is not an issue for me for quite a while.

Since the Spyder warranty is strictly time related, not mileage, it doesn't affect your warranty at all. :lecturef_smilie:

 

[ulflyer]

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

I've run two rears of 205/60 and the General Altimax was 1 mph over, the current Pirelli P4 is about 1 1/2 over.

As to temp readout: mine seems to be closer to 5 over.

 

[bobnaquin]

While pretty much any speedo will read high, in this digital world I am not sure why we don't have a function that allows us to calibrate it to a better known source like a gps, or radar gun, or mile post. It certainly would not be any harder to do then setting the time on a Spyder. I had this feature on a ski boat and it worked very well. Speedboat speedos are inaccurate due to their design. We had a saying in the boating world that all reported speeds were ten mph high: Five from speedo error and five from the owner lying. As far as warranty or service, an hour meter would make a much better gauge. Or better yet an RPM counter. My 2cents.

 

[Bazeel]

I've noticed that my RTS is right at 2MPH 'fast' on the speedometer, as well, confirmed by GPS. I've also noticed the temp bit as well, though it seems that mine will show anything from standard outside temp to about +8 or so, depending!