Whizzer Speedo inaccurate?

[jbcruisin]

Are Whizzer speedometers accurate?? My wife happened to get behind me today & when I got home I asked her "how fast was I going, 35?". She says "35, you were going 45. You better be careful you don't get a ticket!!"
I've been thinking since I installed Quenton's NE upgrade that I'm going faster than my speedo says.
Ain't it great,
Jay

 

[Quenton Guenther]

Hi Jay, I am not sure if the following comments are true, but here are my results. I live in a small fishing village on the east coast and the local law enforcement places a radar unit near one of the bridges about a mile from my shop several times a year. I have checked Whizzer's speedometers against the radar unit at least 50 times in the last few years [I have to pass it on the way to my special test road], and here are the results, the speedometer with the black face [50 MPH version] is approx 1 mile off at 50 MPH [radar reads 51], and 4 MPH off with the later white face speedometer [at 50 MPH the radar shows 54 MPH]. The black face version is almost 100% at 35 MPH, whereas the white face version is indicating 35 MPH when the radar shows 37 MPH. I thought both speedometers are the same, but for some reason they always check differently from the earlier version. On the Whizzer I was testing for the "Dirt Drags" at Dawson Springs, KY had one electronic tachometer, one electronic speedometer, and a Whizzer [black face] speedometer, and the elctronic speedometer and the Whizzer speedometer always checked the same. Hope this answers your questions, but don't forget it is possible for some cable driven speedometers to vary depending mainly on the condition of the cable, speedometer drive gear, and the amount of lube inside the cable.
Have fun, but don't get a speeding ticket!

Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton

 

[JemmaUK]

If there is that much of a difference in the standard whizzer instrument it might be worth getting a secondary digital one...

If thats set up as exactly as possible by physically measuring and inputting the wheel radius manually - then it will tell you what your actual speed is.

Jemma xx

 

[JE]

On my 08 Whizzer when I pass the local radar trailer doing 28mph my speedo is reading 30mph.

 

[Quenton Guenther]

Duh! I just realized some of the bikes I compaired to the radar were 24" and some were 26". I often ride with a friend and he has a 24" and most of the time I ride my 1999 26", he has a white face speedometer and I have a black face. I guess that would explain the different numbers.

Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton

 

[del]

OK, now you've got me curious. As soon as there's a break in the wicked weather around here I'm gonna do a temporary mount of a GPS...

--del

 

[Zev0]

I have a white faced whizzer speedo and a digital speedo. They are within 1 mph of each other. Haven't been able to find a radar setup yet. Don't think they have them within the Phoenix City Limits.

 

[del]

The GPS is temporarily mounted. Tomorrow I'll do a test run to see if I can come up with an indicated v.s. calibrated ground speed chart.

--del

 

[del]

First speedometer test results.

Today I took the bike out and tried to compare the speedometer with the GPS reported speed. There were some problems which I'll type about further down this article. But the initial results are:


Speedometer GPS Difference.

20 16.7 3.3 Mph

30 26.7 3.3 Mph

35 32 3 Mph


The two major problems were holding the bike at a constant indicated speed. (Slight hills would slow down or speed up the bike.) And the lag time in the GPS. (It takes a second or two to get the measured speed to settle down.)

Another problem came when I tried the 35 Mph run. Around here, speeds like that or faster are hard to hold for very long. Folks in SUV's, talking on cell phones, are likely to back out in front of you at any moment. So I'm not that sure about the accuracy of the 35 Mph measurement.

However I do find the first test interesting. The error seems to be fairly constant. Now I have to try to get some accurate measurements at slower speeds.

And, FYI, I'm riding a 2007 NE5 with 24" wheels and a white faced spedo..

As with all things mechanical, your results might be different....

--del

 

[KilroyCD]

Del, I would guess that the 3mph difference is likely to be due to the fact it's a 24" bike. The speedos are likely calibrated for 26" bikes. Looking on Whizzer's website, I don't see any speedometers listed as being for 24" bikes. As a 24" tire is smaller in circumference than the 26" tire, you will be covering less ground for every rotation of the tire. As a result, you're traveling a bit slower than one would on a 26". This is probably why your actual speed is less than the indicated speed.