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ZUMO vs. Speedo

HFD190

HFD190

New member
I have recently installed a ZUMO 550 on my RT. One of the first things I noticed was a discrepancy between the speedometer and the speed on the ZUMO. When the ZUMO indicates 60 mph, the speedo shows about 63-65. I have noticed about the same difference in mileage. I rode 107 miles (ZUMO) a few a days ago and the speedo indicated 112 miles for the day.

So, what is accurate? Holy Cow, how many miles do I really have on my bike?
 
K100LT and a Garmin C330 gps @ 60mph speedo 57mph gps/ 70 mph speedo 65 gps. around 40 and under dead on. At 95 mph speedo 86 gps. The strange thing is the odometer is with the GPS.

Ralph Sims
 
BuddingGeezer said:
K100LT and a Garmin C330 gps @ 60mph speedo 57mph gps/ 70 mph speedo 65 gps. around 40 and under dead on. At 95 mph speedo 86 gps. The strange thing is the odometer is with the GPS.

Ralph Sims
Click to expand...

The speedometers accuracy gets progressively worse the faster you go.
 
Odometers generally have <1% error, but it's not uncommon for speedometers to have 10%+ error, particularly at higher speeds. My '98 F150 pickup, though, at 202,000 miles, still has the most accurate speedometer of any vehicle I've ever owned. It's always been spot-on, either checked with a stopwatch or compared to GPS. My '77 R75/7, though, is a different story. All one can glean from the speedometer is that you are likely traveling between, say, 35 and 50 MPH. I really need to get that fixed... :doh
 
K1200GT and Zumo

I've noticed the same thing on my 2007 K1200GT. At 60 MPH on the Zumo, the speedo on the bike is at 62-63.
 
My Garmin confirms that the speedometer is showing 2 MPH too fast.

As for the odometer, off by 3.1%.

When I turn 36,000 miles and go off warranty, I will actually have enjoyed 37,116 miles of riding (Don't tell BMW!).
 
WildBlue said:
The Zumo is most likely more accurate.
Click to expand...
The Zumo is ABSOLUTELY accurate (I believe Garmin claims less than 1% - way less than 1% error).. BMW speedos are traditionally 5-8% fast, only one I've ever owned (and that's lots of BMW bikes and cars) was on my R1150RS - where it came very close to agreeing with my Garmin.
 
Greenwald said:
My Garmin confirms that the speedometer is showing 2 MPH too fast.

As for the odometer, off by 3.1%.

When I turn 36,000 miles and go off warranty, I will actually have enjoyed 37,116 miles of riding (Don't tell BMW!).
Click to expand...
No - when the speedo indicates 36,000 miles you will have actually gone 34,884.0 miles. Your speedo is indicating MORE miles per mile.. If you want - you can tell BMW about it (although they typically do cover warranty items for a bit past the magic 36k..)
 
deilenberger said:
No - when the speedo indicates 36,000 miles you will have actually gone 34,884.0 miles. Your speedo is indicating MORE miles per mile.. If you want - you can tell BMW about it (although they typically do cover warranty items for a bit past the magic 36k..)
Click to expand...

Dear Don....your expertise in the past has impressed me, so please do not interpret this as 'arguing with you,' but I beg to differ.

My speedometer and odometer enjoy something of an oxymoronic relationship.

Thru testing with LEO radar (courtesy of former buddies of mine still active in enforcement), the speedometer truly is indicating 2 MPH more than I am actually traveling.

However, mile markers and other means of verification (GPS) over lengthy road trips support my conclusion that I have more miles (3.1% more) than the odometer has recorded.

Therefore, I have no reason to contest my mileage with BMW, when I cross the 36,000 mile threshold. I am content.
 
Last edited:
The solution for the R1150GS is to change the drive hub from the stock 3.0:1 to 2.87:1 (621 223 065 32) from the R1150RS That took me from 4.5% too high to exactly matching the 550 as well as road mileage markers.

Your RT shows 2 drives available (item # 6) http://www.webparts.com/diagram.php?btnr=62_0249&mospid=47981&hg=62&fg=05
Depending which ratio you have (marked on bottom of your drive) you can browse all the oilhead models and ratios to find out what works best in your application. Be sure and get an exact difference before shopping.

Or you can just live with it (cheapest option)
 
BMW speedo not accurate

Mr r1200's speedo gets more unaccurate the faster the speed according to the ZUMO....I'm fairly confident that the ZUMO is correct
 
Glad to see that I am not the only one that has noticed this

Yesterday I met up with a friend of mine who is a deputy sheriff (while he was working) and we did a couple of speed tests. He had a certified laser unit (not sure what that means, but sounds accurate) and we did two tests. First with the ZUMO reading 45mph and the other at 60mph. Both times his equipment verified that the ZUMO was exactly correct, which means that the speedo is incorrectly reading high numbers.

And I always thought I was going soooo fast!!!!
 
On my ST the speedo shows 65 and the gps is 61 on the GS it was worse at 75 indicated the gps was 66 this was with three different sets of different make tires the gps was spot on with radar and laser "tests" My buddies LT is 4mph off at 50mph indicated.
 
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