Author Topic: Speedo Error (Read 3526 times)

chevsuz12 · « **on:** September 12, 2005, 09:58:11 AM »

I have just used my GPS on my bike for the first time. Holy crap is my speedometer off!!

At lower speeds it seems fairly accurate, 43.5 at 45. But at high speeds it is greatly off! 91.2 at an indicated 110!!!!! That's roughly 15% off. This is just crazy. Now I must drive faster to make up for going so slow all this time!

I will verify the odometer on the way home.

Desolation Angel · « **Reply #1 on:** September 12, 2005, 10:43:23 AM »

What's with all this speedometer error I keep hearing about? Are cars just as bad? I wonder how much my 1200S is off at various speeds?

At say, 70 MPH, how much faster should I go to REALLY be going 70?

00Bandit Rider · « **Reply #2 on:** September 12, 2005, 10:51:26 AM »

They may get even worse with age, mine is wose than that(40k).
My answer is a SIGMA 800 bicycle speedo. you enter the wheel size so
it's adjustable. only problem I see with it --no light. it has tripmeter, clock, trip time,trip average speed included. the readout goes to 183mph
costs 25$=- Best I could do thru Deals gap was 31 mph av ,getting old.

ray nielsen · « **Reply #3 on:** September 12, 2005, 11:46:52 PM »

I installed a 16 tooth countershaft sprocket and changed rear tire size to a 170/60-17 with an eye toward lower cruising RPM and better turn in when cornering.

The side effect is a much more accurate speedometer, but about 6/5% error in the odometer.

The 2nd gen. Bandit 1200s get the speed signal from a sensor mounted outboard of the front sprocket and tire size and/or gearing changes will cause a shift either for the better worse.

chevsuz12 · « **Reply #4 on:** September 13, 2005, 12:36:07 AM »

I simply took a sharpie and wrote on the glass of the speedo where actual speeds are, 75 by the way is at roughly 87 indicated!

This really screws up the way I ride. I thought that I had a good sense of speed without looking at the speedo, but now my mind is completely screwed up. Especially while traversing city streets with lower speed limits.

Interestingly, the Odometer is fairly accurate, with 30 miles of riding it was only .5 miles off!

Red01 · « **Reply #5 on:** September 13, 2005, 04:31:06 AM »

The 2G odometers are typically pretty accurate and .5 miles out of 30 is probably the worst I've heard. The speedos, OTOH, are notoriously optomistic. (Generally, most m/c speedos are from the tests I've read that include this data - something Motorcycle Consumer News reports.) Folks that have bounced their 2G speedo off GPS or radar usually find the error is exponential. I know my B12's error percentage gets higher the faster it goes.

billster · « **Reply #6 on:** September 13, 2005, 05:04:19 AM »

Every day I pass a radar display setup the PD parks at this school zone....displays your speed in big numbers. I'm usually right on in the lower end. But I often wonder how it is that all these minivan soccermoms and Vulvo drivers are pacing me at 85mph on the expressway.

Should fire up the GPS and check the real speed out.

B6mick · « **Reply #7 on:** September 13, 2005, 06:40:05 AM »

People here in Oz are using GPS tracking to fight speeding notices, and winning. A Month or so back a young bloke driving a WRX, got nabbed by one of our finest, for speeding. The young bloke asked the officer if he was sure if the reading on his radar gun was correct. The officer dismissed the young bloke as a smart ass. Well the young bloke didn't pay the fine or hand in his license ( required here, if P plate drivers are caught for any offence) he requested his day in court. On the day armed with a graph readout and an expert in gps tracking tech, proved beyond reasonable doubt, that the officer was lying about the speed reading, or the speed reading was not accurate.
Young bloke wins, case dismissed, plus awarded costs.
Our finest, some quick explaining to do, and radar gun back to be recalibrated, AGAIN

A very well used, in fact over used excuse.

jfudo · « **Reply #8 on:** September 13, 2005, 10:30:15 AM »

My 1G bandit, as verified with my GPS, has almost a perfect 5% error. Speedo says 40, I'm going 38. Says 80, going 76.

As a side note, I love my GPS. It is one of the cheap units meant for hiking or whatever, it doesn't have any roads on it. It does have the locations of every little town. I like to pick a small town, do a search for it on the unit, it will display the town and make a straight line between me an it. Then I just ride and take whatever roads look fun and I don't have to worry about getting too far off course. I'm a big fan of getting lost, and this allows me to get even more adventurous.

B12Teuton · « **Reply #9 on:** September 13, 2005, 11:31:17 AM »

...just another reason I never looked at my speedo!!

With my 48t rear spreocket it was about 14% or more!