Is the speedometer way off on the '04 RT?

[Pier]

Hello everyone. I was riding today on my new ( for me ) 04 RT and while riding on the highway I thought the speedometer was wrong. By the way, I have three other bikes so I'm used to detecting speed from a motorcycle, but I thought that my new RT was just showing off herself a little. Usually on the same road I notice the speedometer pointing at 70-75 on my other bikes, but the RT tells me I'm at 80-85.

 

If this help by comparing my RT to yours I can say that at 70 MPH the RPM were at 3500 on the 6 gear. At 60 MPH the RPM were at 3000. All this may sound very familiar to all of you but I'm still trying to learn about my new bike.

 

Thank you for your replies.

 

Pier

[TMH]

One of the best ways to determine speedometer accuracy is to take a GPS out for a little while, and compare its speed to the speedo's.

 

I have heard that most German automotive and bike speedometers are, for lack of another word, "optimistic". My understanding is that this relates to a German law which is very stringent (and can result in large fines to the Manufacturers) if their speedometers are found to read too low. Therefore, they err on the side of optimism. Truth or Urban Legend? Don't know, but it sounds like it could be true.

 

Tom

[Jerry Johnston]

10mph seems a bit much. When this question came up a year or so earlier the average was 5mph optimistic. Using the GPS I found my old 86 Nissan pickup is Opt. by 5mph, the 95 Ponitac is under by 5mph and the 93 Pathfinder is right on the money. My Rt is 5mph opt. also.

[HexST]

BMW's are notorioulsy off by as much as 10%. Thats why some people use their GPS's for speed. My GS was off 10% at all speeds threee dealers said it was in tolerances and that the Company does that for your own good. Even though you are out of waranty 10% sooner. My ST is anywhere from 5 to 8 mph high at all speeds above 60.

[jacko]

I have a 02 1150rtp,its a aussie model so the speedo is in kilometers. Its about 3kmh out compared to my gps.

On a ride of 7315 KM the gps showed 7299 km

pretty close

regards Jacko

[Ken/OC]

Based on many past posts and my own experience, most 1150RTs read 5-10% high on speed. The odometers are, however, quite accurate, so this doesn't affect the warranty limits. Just maybe get you a ticket or two fewer.

[bmweerman]

Can't make an exact comparison because I ride an 1100 with 5 gears, but checking against GPS showed about 10% discrepancy...speedo reads faster than actual speed.

[AnRSguy]

I agree and think my '04 RT is also optimistic. A guy at Bob's said that if I would buy the speedo drive that is on the front wheel from one of the earlier bikes it would fix it, all for only about $85. I passed.

 

On a short trip a week ago on I-95 in VA, I was going 85 and cars were passing me regularly.

 

On the other hand at lower speeds it seems accurate. I want a GPS but right now it tough to justify just to check my speedometer.

[Beemeroil]

Welcome to the joys of being a beemerhead. For a more accurate speedo, and without the cost of GPS, go to your local bike dealer and buy a bicycle speedometer which will be far more accurate and show speeds as high as you can go.

[BruceWA]

My 04 RT has exactly a 4% error on the odometer and about 8-10% on the speedometer.

[BobFV1]

TADT - mine is 8-10 percent high

[PETDOC]

Unless the RT is significantly different than my 04 GS I'd find another dealer for a quote on the different ratio speedo hub. Most GSs read 7-10% faster than real speed. I purchased lower ratio speedo hub from Chicago BMW for about $35. Installation took about 10 minutes. Checked with GPS and I'm now within 1-2% of real speed.

I don't understand how a speedometer can read 10% faster and the odometer be accurate since they both depend on the same drive unit. Anyone care to explain this enigma to me?

[lithoman]

I've heard that too, mine i don't think is that far off, I don't have a GPS to check, but I have tested it against my wife's land cruiser and if she was doing 70, my bike read 73

not too bad?

[KMG_365]

My 2003 RT's speedo reads 9.5% high, but the odometer only reads almost exactly 3% high. The odo is driven directly by a cog, but the speedo is driven by magnetic eddies between the metal cup attached to the needle (held back to zero by a coiled watch spring) and the magnetic disk attached to the end of the cable which spins inside the metal cup. You can adjust the accuracy of the speedo by affecting the strength of the magnetic field (about USD $250.00 shipping it to Palo Alto Speedometer), or fix both by replacing the driving gear on the front wheel with the one for the R11xxRT-P for your model bike. Or--buy a GPS and have accurate speed, maps of the whole world (including gas stops and lodging) and a couple of different trip meters!

[PETDOC]

Thanks Jamie, I never knew that about how speedometer works. On GPS I'm waiting for real time satelite weather(which is here with Garmin) and a rear view camera so I can be stopped in traffic and see what's coming up behind me. Obviously rear view is available in many car units, don't know why someone hasn't put it in one for bikes.

[TonyS]

Before you get too comfortable thinking you're going a lot slower than the speedometer indicates (but Officer, everyone tells me my speedometer reads way high), my 04 RT reads at least 77 mph when my Garmin 2610 shows 80 mph. I check this all the time and find the speedometer is at most 2.5-3 mph off. My friend's 1150 GS reads 5 mph faster than my RT.

[ShovelStrokeEd]

1100S is 9.4% optimistic. Blackbird 8.4%, my GS was 8.8%, it all varies with wheel diameter. Your GPS can vary as well depending on your vertical speed so don't always take it as gospel.

[harpoon47]

My '04 RT reads about 4mph faster than the GPS. This is BMW's intentional design to reduce speeding tickets so we'd have enough money to pay for service and parts.

[bmweerman]

My '04 RT reads about 4mph faster than the GPS. This is BMW's intentional design to reduce speeding tickets so we'd have enough money to pay for service and parts.

 

Now THAT'S funny!!

[sisu]

Both of my oilheads were optimistic on the speedo by about 7/8%, the odo by about 2%. The speedo on my new R1200RT is about 2/3% fast, the odo is about 1/2% pessimistic. I had several Audis in a row that had the speedo right on the money, same as my GMC pickup.

[ogjimbob]

in the UK it is accepted that vehicle speedo's will read up to 10% high this is to protect the manufacturers from the accusation that their vehicles allow people to speed inadvertantly.

God alone knows what the Japanese sports bikes are for :-)

[GlennW]

Both my bikes (an '03 RT and an 'O1 Kawasaki ZRX) read about 9% high as compared to a GPS. I installed a $20 bicycle computer on the Kawasaki and calibrated it to read within about 1%. I have not done so on the RT, but there should be no major installation problems. Asside from getting accurate speed, you also get average speed, max speed, a ride timer, a clock, and an extra resettable odometer (very usefull for tracking oil changes).

 

The only catch is that many cycle computers won't read speeds above 70-80 mph. The Sigma Sport BC800 and BC1200 both will read well over 100 mph (I've used mine up to 110). If possible, buy the model specifically made for a rear wheel installation on a bicycle; it has a longer sensor cord. My BC800 had the shorter front wheel mount cord and required splicing to fit the motorcycle. You'll also have to buy a stronger magnet to mount on the brake rotor carier, as the small stock magnets are inadequate.

 

One last note. The wireless bicycle computers probably will not work. The bike's ignition circuits generate quite a bit of radio interference. My brother tried a wireless unit on his Harley with no success.

 

Hope this helps,

 

GW

[bimmers]

interesting issue on a whole. Have some friends who bought a dealer demo car with larger rims / wheels mounted. Could not understand why the mileage was so poor compared to promised values. Realized that traveled distance was showing less as the revolutions per distance were less. Realized the car had more actual miles on it and demanded a discount to reflect that. End reslut after numerous discussions was that they replaced the tires / rims with original size ones and he got some other benefits. He was happy etc.

THis is something that is rarely thought of but of course as tires wear the circumference changes and that would require calib. of odo and speedo. On cars the flat tire alarm does get recalibrated at times.

When meeting LEO the speedo is always showing OF COURSE showing less, believe me or NOT!!!!!!!!!!!!