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Speedometer Accuracy?

G

gvmerle

Bicycle
I am sure someone has checked the accuracy or lack of on the C-14 speedometers.  Can anyone tell me about how much over the actual speed they read?  I don't have a GPS yet and fortunately, haven't been stopped for speeding.

Thanks.
 
Mine was probably about 5%fast. As speed went up, the faster it would read. So when I was doing 75 on the speedometer, I was really doing about 71-72. 80 mph was really about 76. So a quick figure is about 5mph at highway speed. But if you use the speedometer as being correct, you have a window of margin as a cushion!  :D
 
I realize this is a C14 thread, but on my C10 I also find my speedo and my odo are not in sync. Meaning different error factors.  While using the GPS to track speed, and with the current tires, I find the speedo to be quite close. Maybe 1% at best. 76 on the speedo is 75 on the GPS. However when I track ODO readings though I have used the GPS mileage feature, Streets and Trips plotting as anal as can be about every little turn, etc I find the ODO is more like 3.5% off.

Most C10 owners the speedo is a little fast. And Wing Tars make them more accurate. I am one of the few where I get a accurate speedo with the stock tires. And the Wing Tars made my speedo run slow. But my ODO was pretty much spot on. I once rode a SS100 with a fellow COG riders, one had a GPS. My ODO was to the mile with the GPS. Everyone else was high 30-40 miles. I was right to the mile at 1044 mi. HOWEVER while I was thinking that 67.5 on my speedo was 70 in actual  ( slow ) on that same SS100 Wash State Patrol confirmed for me that 67.5 was 71 on the radar gun.

So the point being only that the speedo and the odo dont necessarily track the same error factor. Well at least in my case anyway.
 
My 09 is about the same as the others, about 3 MPH fast at 60 up. But my odometer is only off by about by 1.4 miles very 100. A lot better than my Gold Wing , it was off about the same on MPH but added 4 miles to the odometer every 100.
 
Thanks for the responses.  I will go with 5% error.  On the Goldwing, I always run with the speedometer reading 5 MPH faster than the speed limit and that leaves me 1-2 MPH error as too fast.  Back in the day, I never cited anyone unless they were doing 10 MPH or more over the speed limit.  I'm sure that is not a standard but always feel pretty safe if I am within 5 MPH.

Thanks again.
 
GVmerle said:
Back in the day, I never cited anyone unless they were doing 10 MPH or more over the speed limit.  I'm sure that is not a standard but always feel pretty safe if I am within 5 MPH.
Click to expand...

I assume this means you were/are in law enforcement. I know of a guy in one city police department who gives up to 10 over in many situations. But in a school zone 20 is 20. He has been known to write people for 22, 2 over ( not me ).
 
I agree, there are places and times where speed limits should be strictly obeyed or speeds should even be lower than the posted speed limit.  And, at times 10-15 over is not dangerous.  Depends on conditions and surroundings.  This is a personal opinion of course.
Yes, I was an officer in So. Cal. for 29 years.  Good job but glad to be retired and riding the Concours.
 
I put a SpeedoHealer on my bike to fix the speedo error. If I remember right, I have it programmed to apply a 4% correction factor, and now its dead on at all speeds.

http://www.pbase.com/fredharmon/speedohealer
 
When i did the gauges light color change i did a little adjustment to the speedo neddle at the moment of put it back and now it read same as the GPS
 
3 MPH diff between the GPS and the speedo ...consistent at all speeds .so for me that is 0-120
 
I finally got a GPS mounted on my Concours and found that the speedo is off 3 MPH at all speeds that I have driven.
 
I would think that the error would not be a linear x mph.  Mine is off 3.5 to 4 percent.  Meaning at 50 indicated I am only going 48ish.  At 75 indicated, gps has it at 72ish.  I wonder if there were code changes in reading the speed sensor.
 
with the new Michelin P3 tire size 190x55 (all that was available a month ago when I got it thru the dealer), the speedo error is only 1 mph from 60-80  approx, at 100 its off 2, 98 according to gps.
 
Every bike I have ever owned was off by about 5% (speedo ALWAYS reads higher than actual).  I am not sure why every manufacturer does this.
 
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