Radar says: 33mph, my speedo says: 35mph

Now that I've put on new tires, I gotta go find another portable radar and recheck as the diameter of the tires is a bit different.

 

I don't trust radar...at all...especially on a bike. Somehow I remember a simialr article (and I may actually still have that magazine laying around) where they tested bikes on police radar. If I remember correctly, bikes never seemed to give an accurate reading..compared with a car. Something about the size/angle of the bike...tell you the truth, I don't remember. But same with those roadside speed check things...they never give me a reading that's accurate in any vehicle I'm in/on...car or bike.

Really, I will only trust GPS. I don't really know much about it because I don't own one. But I've ridden with enough people...and ridden alongside a car with a nav system..and always, my bike's speedometer isn't accurate with the GPS/nav. It always seems to be reading about 5 mph faster than I'm actually going.

If I could do a more thorough test with a bunch of GPS/nav equipped vehicles, and then come out with an average, then I'd be happy. To be honest, it doesn't really bother me if my speedometer is reading 5mph higher than actual speed. If anything, it means I can safely go 5 miles per hour faster But I won't be happy until I can do more tests....or get more replies from other harley owners. From the varied replies here, I can see that this isn't going to be easy to get a truly accurate answer.

Todd

 

My Ultra is spot on up to about 65, then it gets a tiny bit optimistic. According to the stopwatch/milepost method, it reads 78 mph at 75 mph calculated, a 4% error. Close enough for me.

 

According to several of the mobile radar speed signs my RK is right on....Now my old Yamaha Warrior....Now it was way optimistic....60mph on the display was really about 54.... Really made you feel cool though when you looked down and the display was registering 115.....Once I had it to 150....but then I realized I had set the display to KPH by mistake....always meant to try to take a picture of that!

 

This last weekend I took a long ride and happened to see one of those areas where you can test your mileage by the markers along side the road. I kept my bike at 60 and at the end of the 5 mile test area, my bike was only 2/10ths off from the start of the test. I don't know how accurate that test is, but I satisfied my curiosity anyway.

p.s. I also got stopped by a LEO and he said that he clocked me going 74 in a 55. He was right because I was speeding. Lucky for me, I talked my way out of the ticket. WHEW

 

Most automotive and motorcycle GPS defaults to MPH....aviation and marine units are usually nautical miles.

 

I have done the same and my speedo on my FXDI seems to be off by about 1 mph too.

My Sportster used to be off by about 5 mph.

 

agree mine at 70 is =/- 1 mph by gps reading

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Mine is spot on , I've measured it a few times

 

when i went through my last police motorcycle operators course- there is a maneuver that requires you to enter a chute at 40mph and brake (hard) and at the end of the chute, make a hard right turn to avoid an obstacle (brake and escape).

our entry speed was checked with radar.

my particular motorcycle read about 2mph higher than indicated on radar.

however, it IS a police motorcycle which has been dropped MANY MANY times by varying riders....

my King is right on though