All,
After seeing all the threads about correcting the speedo error, top speed, tires, and how fast will an FZ go, I had to look a bit deeper. With that here is a formula that should give you the corrected speed based upon gear selection, sprocket choice, and tire diameter.
Obviously tire pressure and speed will change the rear tires rolling distance but I'm not going to get into that! In short if you have Stock Gearing and the manufactures recommended rear tire; If you hold your RPM's at 6,000 you should get the Speeds listed in Bold in all Six Gears (27, 40, 50, 59, 66 and 72mph)! There are other variables, but this should be pretty close. If you change sprockets or Tire diameter, use the formula to punch in the correct values so you can see how far off your speed is.
Formula is:
RPM * PIE * Tire Diameter (inches)
---------------------------------- = Speed in MPH
1056 (constant) * Actual Drive Ratio
So now we add in all the variables:
TIRE:
Stock Tire: 180, 55 ZR17 73W
Hint: Z rating is rated at 149mph with a max speed of (W) = 168mph
Tire Diameter: 24.8"
Circumference: 77.9"
Revs Per Mile: 813.39
RATIOS:
Primary Ratio: Engine to Trans (PR): 86/44 = 1.9555
Secondary Ratio: Sprockets (SR): 46/16 = 2.8751
- - - - - - - - - - - - - - - - - - -
TRANSMISSION RATIOS:
G1 = 37/13 = 2.846
G2 = 37/19 = 1.947
G3 = 28/18 = 1.556
G4 = 32/24 = 1.333
G5 = 25/21 = 1.190
G6 = 26/24 = 1.083
- - - - - - - - - - - - - - - - - - -
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
RPM * PIE * Tire Diameter (inches)
---------------------------------- = Speed in MPH
1056 * PR * SR * G#
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
1st Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 27.6MPH
1056 * 1.9555 * 2.8751 * (G1) 2.846
2nd Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 40.4MPH
1056 * 1.9555 * 2.8751 * (G2) 1.947
3rd Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 50.6MPH
1056 * 1.9555 * 2.8751 * (G3) 1.556
4th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 59.0MPH
1056 * 1.9555 * 2.8751 * (G4) 1.333
5th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 66.2MPH
1056 * 1.9555 * 2.8751 * (G5) 1.190
6th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 72.7MPH
1056 * 1.9555 * 2.8751 * (G6) 1.083
haha! Confirmed! :thumbup: Speedo was correct!
2nd Gear @ 14,000 RPM:
14,000 * 3.1415 * 24.8
---------------------------------- = 94.3MPH
1056 * 1.9555 * 2.8751 * (G2) 1.947
Plug in the numbers for the variables on your bike and watch the tach! This should tell you pretty close to what your actual speed is!
To get the tires diameter use this!
Remember there are many variables so this is to get us "close"!
********************************************
Using a stock Tire Size of: 180/55 R17
The first number is the Tire's indicated section width in millimeters, measured from sidewall to sidewall. {180}/55R17
Section Width: 180 is converted to inches!
180mm / 25.4 = 7.0866"
Profile or Aspect Ratio: 55
The second number 180/{55}R17 is the tire's aspect ratio or profile.
55% or add a decimal point 0.55
Sidewall Height (SH):
SH = 7.0866" X 0.55 = 3.897"
Wheel Diameter (WD): 180/55R{17"}
WD = 17"
Tire Diameter in Inches:
SH + SH + WD = Tire Diameter
3.897" + 3.897" + 17" = 24.8"
********************************************
********************************************
I Hope you find this useful! If anyone sees any errors, let me know and I'll correct them!
Regards,
FI
JJD952 - Speed
EDIT: 2015-05-22, added real data from new and used tire
After seeing all the threads about correcting the speedo error, top speed, tires, and how fast will an FZ go, I had to look a bit deeper. With that here is a formula that should give you the corrected speed based upon gear selection, sprocket choice, and tire diameter.
Obviously tire pressure and speed will change the rear tires rolling distance but I'm not going to get into that! In short if you have Stock Gearing and the manufactures recommended rear tire; If you hold your RPM's at 6,000 you should get the Speeds listed in Bold in all Six Gears (27, 40, 50, 59, 66 and 72mph)! There are other variables, but this should be pretty close. If you change sprockets or Tire diameter, use the formula to punch in the correct values so you can see how far off your speed is.
Formula is:
RPM * PIE * Tire Diameter (inches)
---------------------------------- = Speed in MPH
1056 (constant) * Actual Drive Ratio
So now we add in all the variables:
TIRE:
Stock Tire: 180, 55 ZR17 73W
Hint: Z rating is rated at 149mph with a max speed of (W) = 168mph
Tire Diameter: 24.8"
Circumference: 77.9"
Revs Per Mile: 813.39
- - - - - - - - - - - - - - - - - - -Adding ACTUAL TIRE ROLL OUT DATA.....
Used mounted 37PSI:
Roll out: 75.5", wear passed tread bars
Tire OD: 24.03"
NEW mounted 37PSI:
Roll out: 77.375"
Tire OD: 24.63"
Tread bar depth near center: 0.22"
From: Old to New Tire Roll out vs Speedo Error = 2.5%
RATIOS:
Primary Ratio: Engine to Trans (PR): 86/44 = 1.9555
Secondary Ratio: Sprockets (SR): 46/16 = 2.8751
- - - - - - - - - - - - - - - - - - -
TRANSMISSION RATIOS:
G1 = 37/13 = 2.846
G2 = 37/19 = 1.947
G3 = 28/18 = 1.556
G4 = 32/24 = 1.333
G5 = 25/21 = 1.190
G6 = 26/24 = 1.083
- - - - - - - - - - - - - - - - - - -
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
RPM * PIE * Tire Diameter (inches)
---------------------------------- = Speed in MPH
1056 * PR * SR * G#
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
1st Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 27.6MPH
1056 * 1.9555 * 2.8751 * (G1) 2.846
2nd Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 40.4MPH
1056 * 1.9555 * 2.8751 * (G2) 1.947
3rd Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 50.6MPH
1056 * 1.9555 * 2.8751 * (G3) 1.556
4th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 59.0MPH
1056 * 1.9555 * 2.8751 * (G4) 1.333
5th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 66.2MPH
1056 * 1.9555 * 2.8751 * (G5) 1.190
6th Gear @ 6000 RPM:
6000 * 3.1415 * 24.8
---------------------------------- = 72.7MPH
1056 * 1.9555 * 2.8751 * (G6) 1.083
haha! Confirmed! :thumbup: Speedo was correct!
2nd Gear @ 14,000 RPM:
14,000 * 3.1415 * 24.8
---------------------------------- = 94.3MPH
1056 * 1.9555 * 2.8751 * (G2) 1.947
Plug in the numbers for the variables on your bike and watch the tach! This should tell you pretty close to what your actual speed is!
To get the tires diameter use this!
Remember there are many variables so this is to get us "close"!
********************************************
Using a stock Tire Size of: 180/55 R17
The first number is the Tire's indicated section width in millimeters, measured from sidewall to sidewall. {180}/55R17
Section Width: 180 is converted to inches!
180mm / 25.4 = 7.0866"
Profile or Aspect Ratio: 55
The second number 180/{55}R17 is the tire's aspect ratio or profile.
55% or add a decimal point 0.55
Sidewall Height (SH):
SH = 7.0866" X 0.55 = 3.897"
Wheel Diameter (WD): 180/55R{17"}
WD = 17"
Tire Diameter in Inches:
SH + SH + WD = Tire Diameter
3.897" + 3.897" + 17" = 24.8"
********************************************
********************************************
I Hope you find this useful! If anyone sees any errors, let me know and I'll correct them!
Regards,
FI
JJD952 - Speed
EDIT: 2015-05-22, added real data from new and used tire
Last edited: