Speedomoter Wrong?
I've never seen an accurate bike speedo. Mine's always been +3 or so on the read out. I like it cuz I always know I'm traveling a bit slower than indicated. Still got a ticket on the way to Daytona though
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
My bike is about 5% and my car 6% fast compared to the GPS, and you can bet the GPS is right. Most (all?) modern speedometers are optimistic, I presume for legal reasons. For example, ponder this scenario: Some schmuck is riding at an indicated 60mph in a 60mph zone, but because his speedo is 1mph slow he's actually going 61mph. If he gets in a wreck it would be a glorious opportunity for some ambulance-chaser to sue the manufacturer. The argument might be that he was going "faster than what is safe" because his speedometer was inaccurate. My 2˘.
Last edited by iclick; May 23, 2010 at 12:07 PM.
Cruiser
Joined: Jul 2007
Posts: 179
Likes: 3
From: Ocean View, DE
In two cars I have driven the speedo was dead on with the GPS. On my 2009 FLHTC the speedo reads 3mph faster at highway speeds. This is not sounding like a random error due to the lack of precision of the instruments. This sounds like an accross the board error in the calibration.
Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
For those who don't have a GPS to check your speedometers, you can do it the old fashioned way--with your watch. This chart is from the Mn Highway Patrol. Set your cruise, or hold a steady speed, and check your speedometer from mile post to mile post, and compare on this chart.
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Outstanding HDF Member
Joined: Apr 2006
Posts: 2,395
Likes: 25
From: St George, UT
On a trip to Texas
my GPS recorded a total of 2297 miles rountrip, while the odometer showed 2356 miles, a difference of 3.5%. I experience the same variations others have commented. 78 mph indicated is 75 GPS mph, etc. The only speed that agrees totally with the GPS is 50 mph.
Outstanding HDF Member
Joined: Apr 2010
Posts: 3,373
Likes: 4
Once again a GPS doesn't (obviously) read speed the same way as your speedo. You get speed from a GPS by looking at where you are at one time, and
where you are at another, and dividing distance by time. You speedo is based on revolutions of your wheel. Put simply.
where you are at another, and dividing distance by time. You speedo is based on revolutions of your wheel. Put simply.