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Gearing/Speed Calculator for all bikes

36K views 33 replies 23 participants last post by  legiteuphoria 
#1 · (Edited)
Ok guys. I know a lot of us have been wanting a speed calculator since the switch over to the new forum software. So today I happen to be over at 600RR.com and found one for the 600RR. I took that and did some tweaking so you can use it for any bike. All you have to do is get the gearing ratio and tire size from the manufacturer.

Enjoy!




*Requires MS Excel.

**EDIT - Metric conversions added
 

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#3 ·
whats the difference between the bluye and yellow?
 
#7 ·
yYea its nice!!
 
#9 ·
flamedRRider said:
Is that spreadsheet based on actual calculations or the speedometer readings. What I mean is does the spreadsheet give what speed the speedo is supposed to read (without error)?
Yes. The calculations are based on the actual gearing ratios in the tranny, the tire profiles, and the sprockets. True speed.
 
#10 ·
cool sheet - how can i change to kms - i see it's protected fields :(
 
#12 ·
NewRedRider said:
Yes. The calculations are based on the actual gearing ratios in the tranny, the tire profiles, and the sprockets. True speed.
What tire did you use in the assumption? New, used etc.? Because different manufacturers will use different profiles and will change the equation slightly. I.E. GPA's are taller than Powers, etc.
 
#15 · (Edited)
tiltedworld said:
What tire did you use in the assumption? New, used etc.? Because different manufacturers will use different profiles and will change the equation slightly. I.E. GPA's are taller than Powers, etc.
Good question. Because each manufacturer's idea of what tire profile sizes really are, the calculations are based on standard measurements (mm). If you want to be exact on your calculations break out your micrometer and measure your tire profile. Let's say you measure 180 (mm) width and 105 (mm) hieght/depth. Divide 105 by 180 and you get .583333. Multiply by 100 and you get 58%. So your ACTUAL tire profile would be a 180/58/17. Put these numbers into the sheet and you get your corrected speed for your tire.

However, this would only equate to a 1.6% difference in speed at 15K rpm. Your talking about 3 mph. Not enough for the common rider to worry about.
 
#16 ·
coolaid said:
is this the same calculations to tweek the speedo healer? if so how do you apply that to the speedo healer?
I haven't used the speedo healer so I don't know how to calibrate it. Now that you have the spreadsheet to verify, maybe someone with the knowledge will post up. You could always send the manufacturer an email and ask them how to calibrate it.
 
#26 ·
sorry for my ignorance, i've figured out that the final drive is nothing more than the rear sprocket teeth / front sprocket teeth and knowing that i've duplicated your spreadsheet, the math is really simple. Thanks for the idea, it's cool to look at this data for different bikes and comparing sprockets for different tracks.
 
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