How fast am I really going? | GTAMotorcycle.com

How fast am I really going?

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crackerjack

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This might be a dumb question, but I'm gonna ask it anyway. Am I going as fast on my bike as my speedometer says I'm going? If my speedometer says i'm going 80km/h am I going 80km/h or am I going slower than that. I told a guy who rides that I like to cruise at 100km/h on the highway. He said that even though I thought I was going 100, I was probably only going about 90. I just assumed he's an idiot and didn't really think much of it until I read about it in a post yesterday. I believe a guy said his speedometer said 80km/h but he was really doing about 72km/h. So whats up with that? Why would your speedometer say one thing, but your actual speed is different? I'm not convinced its true. What do you guys think?
 
Speedometer on bikes are slightly off. Strap a gps and see what it actually says?
 
This is true. I've been parallel to some cars with digital speedo's and while mine is saying 51 his is saying 45. Same with those radar boxes that tell you how fast your going, my numbers never seem to match
 
My V-strom is around 7-8kph higher than GPS verified actual speed although I haven't verified that at very low speeds (i.e. if the speedometer reads 6kph, I am surely not going backwards).
 
stock is about 10 percent less speed, so if you are going 60 on the speedometer you are going 54 on the GPS, 100 you are going 90, 140 you are going 126 aprox etc etc
 
some bikes like those from BMW are actually 100% bang on accurate. Also, some people add "speedo-healers" to their bikes to fix the speedo error.
 
kiwi said:
some bikes like those from BMW are actually 100% bang on accurate. Also, some people add "speedo-healers" to their bikes to fix the speedo error.
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Not always though. I've got an old BMW and I can confirm that mines a good 5-8 kmh off.
 
Oh, and here's a bigger conundrum, even though the speedo is off, and both the speedo and the odometer read off the same sensor, the odometer will be correct even though the speedo is out....This doesnt talk about changing sprockets, just the factory built in error.

All the bikes i've had read on the low side. Honda, Suzuki, KTM, Kawi.
 
Yeah, it's a deliberate thing. Engineering an accurate speedo isn't exactly a big problem. I remember reading that the tolerance they can get for an average car or bike is within 0.02 or better (sorry, don't have a link for that because it's been a while), but that they make it read low on purpose to help prevent speeding tickets, keep people out of trouble, etc. etc.

Kind of like if your clock was 5 minutes fast and you never figured it out.

The main problem is that it's more severe for bikes, so if you don't know it you might be in a situation where some guy in a car is tailgating you and here you're thinking "Man, I'm already 10/20/whatever over the limit!" not realizing that his speedo shows you only doing the limit.

Of course if you DON'T know exactly how far your speedo is off, it's not a good idea to guess!
 
always amusing when a newbie or friend of newbies brags their stock (insert 600cc sportbike here) does 280km/h
 
Yup the GPS can be depressing or reassuring - but figure 10 percent low as rough guide.
 
crackerjack said:
This might be a dumb question, but I'm gonna ask it anyway. Am I going as fast on my bike as my speedometer says I'm going? If my speedometer says i'm going 80km/h am I going 80km/h or am I going slower than that. I told a guy who rides that I like to cruise at 100km/h on the highway. He said that even though I thought I was going 100, I was probably only going about 90. I just assumed he's an idiot and didn't really think much of it until I read about it in a post yesterday. I believe a guy said his speedometer said 80km/h but he was really doing about 72km/h. So whats up with that? Why would your speedometer say one thing, but your actual speed is different? I'm not convinced its true. What do you guys think?
Click to expand...

OP so if that guy was right, that means he's not an idiot. Who is then huh?
lol
 
What type of bike do you ride? My 250 is definitely 10% high from actual speed. I checked it with a GPS and : 80 is 72, 100 is 90, 120 is 108...
 
My owners manual even says the speedometer is 8 percent higher than actual. I don't understand why they do this on motorcycles.
 
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My cars have almost all read high, too, but I'm told that is now not common.
 
well if its true then i think my 09 600rr is off by 5km. my contour camera has the gps feature and i figured the gps was just crappy and slow on the camera because theres a couple vids you can see the speedo and the gps speed. i have the gs set to ping 5x per second which is the highest rate te contour will do.
 
The speedo discrepency is a built-in safey feature from the manufacturers. Best to let everything think they are going faster than they are - especially on a motorcycle.
 
FActories do this so you can't blame them if you have an accident at an off ramp that has a sign suggesting 60 kmh....and you go in at 60 kmh and crash. Should you discover the factory allowed the bike to leave their factory actually going higher than that spoeed, while indicating 60 kmh to the rider on the speedo, they fear you may have some grounds for a law suit. This way, they have actually given dummy riders room for error of judgement. They can't outlaw stupidity, so they bubble wrap it instead.
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