ncsonderman Posted February 19, 2014 Share Posted February 19, 2014 I haven't hooked up a GPS to the GSA yet and wonder if someone can share what my actual speed is at different speeds vs. my speedo? I know on my RT that I am only travelling 72 when my speedo lies and says I'm doing 80. Thanks for the help. Better safe than pulled over Link to comment
Tri750 Posted February 20, 2014 Share Posted February 20, 2014 I forget the formula that BMW used to use. It was something like 3 or 5 percent plus 2 miles an hour. If you say 7 mph optimistic, your likely right there. Link to comment
dirtrider Posted February 20, 2014 Share Posted February 20, 2014 I haven't hooked up a GPS to the GSA yet and wonder if someone can share what my actual speed is at different speeds vs. my speedo? I know on my RT that I am only travelling 72 when my speedo lies and says I'm doing 80. Morning Joe Motorcycle speedometer indicated speed is a difficult thing to pin down. The basic US & European rule is that the vehicle's (actual) travel speed should never be higher than the (speedometer) indicated speed. That is a tough thing to always assure as tire diameter, tire type, tire wear, tire temperature, tire pressure, load on the tire, & tire construction all play a role in how the speedometer reads the tire distance traveled per revolution. Then on the GS, GS-A there are so many tire types & lug depths that trying to predict the speedometer accuracy is a guess at best. Assuming the BMW GS, GS-A doesn't get a different speedometer calibration for US import it probably runs under the (UNECE) regulations of indicated speed should not be more than 110% of actual speed + 4 km/h. Most late model BMW GS,GS-A speedometers that I have had my GPS on run about 5+mph fast @50mph & a little over 10+mph fast at 100 mph. My Hexhead GS-A OEM speedometer runs about 7mph fast at 60mph & close to 15mph fast at 100 mph with worn TKC80's on it. To really know what your bike is doing you need to run a timed mile, or use a (good) GPS on a flat level road running with the tire type/brand , air pressure, & load you want to calibrate to. Link to comment
Haynes Posted February 21, 2014 Share Posted February 21, 2014 It's not a linear error. Speedo 60km/hr, GPS 56km/hr. Speedo 100km/hr, GPS 94km/hr. Speedo 120km/hr, GPS 114km/hr. Link to comment
Huzband Posted February 21, 2014 Share Posted February 21, 2014 My '08 RT was slightly worse than my current '07 GSA. This is a shot of my speedo in west Tx on my 50cc. Cruise was set at 88mph by GPS. I don't have a corresponding shot of the GSA speedo, but I have noticed it's much closer to the GPS than the RT was. I found last Thu on I=95 coming home from Kissimmee an indicated 82 gave me a dead on 80 GPS reading. Link to comment
ncsonderman Posted February 22, 2014 Author Share Posted February 22, 2014 Thanks gentlemen! This bike is smoother than the RT but catches the wind more. I look forward to many adventures on it. I've got to convince some friends that it isn't too pretty to take off road Link to comment
ThomasJ Posted February 23, 2014 Share Posted February 23, 2014 "This is a shot of my speedo in west Tx on my 50cc. Cruise was set at 88mph by GPS." 80 mph on a 50cc? that's something I would like to see! Link to comment
Huzband Posted February 23, 2014 Share Posted February 23, 2014 "This is a shot of my speedo in west Tx on my 50cc. Cruise was set at 88mph by GPS." 80 mph on a 50cc? that's something I would like to see! Link to comment
dirtrider Posted February 23, 2014 Share Posted February 23, 2014 "This is a shot of my speedo in west Tx on my 50cc. Cruise was set at 88mph by GPS." 80 mph on a 50cc? that's something I would like to see! Afternoon Huzband That would be the Iron Butt 50CC Quest not a 50cc motorcycle. http://www.ironbutt.com/ridecerts/getdocument.cfm?DocID=4 Link to comment
Huzband Posted February 23, 2014 Share Posted February 23, 2014 "This is a shot of my speedo in west Tx on my 50cc. Cruise was set at 88mph by GPS." 80 mph on a 50cc? that's something I would like to see! Afternoon Huzband That would be the Iron Butt 50CC Quest not a 50cc motorcycle. http://www.ironbutt.com/ridecerts/getdocument.cfm?DocID=4 Yeah, yeah. Splitting grammatical hairs. ThomasJ was obviously cracking wise at my expense, & I'm still laughing about it. Link to comment
lkchris Posted February 24, 2014 Share Posted February 24, 2014 For sure in the Airheads and early K eras, BMW produced Service Bulletins describing "Speedometer Advance." In both versions I have, they hasten to note that the odometer is accurate. Link to comment
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