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Set the yellow boxes to your stock settings, Set the red boxes to new or desired settings.
Calculated boxes will refresh when cells are updated (and the enter key is pressed) but to force a refresh, use the "Refresh All Calculated Values" button.
Tab (and shift-tab) can be used to easily move between form boxes.

Have some stock values for a bike? Send them to me and I'll add it to the list.
Stock Gearing New Gearing
Counter Shaft
Rear Sprocket
Engine Max RPM
Torque Percent Change

Stock Gearing New Gearing
Primary Reduction
Final Reduction
Overall Ratio In 6th

Rear Tire
Stock Gearing New Gearing
Tire Width (mm)
Aspect Ratio
Wheel Radius (in)
Wheel Size (mm)
Top Speed MPH
Top Speed KMH

Stock Gearing Top Speeds
Overall Ratio Top Speed MPH Top Speed KMH

New Gearing Top Speeds
Overall Ratio Top Speed MPH Top Speed KMH
Thanks to N20CBR for providing the original Excel file.
Thanks to North Rider F4i forwarding the original and requesting an update.
Thanks to UrTerminal for converting to a web-based form.

* All equations are taken from Motorcyclist Magazine.

Stock Specs 2002 CBR 600 F4i


WheelBase 1384 mm / 54.5 in
Length 2010 mm / 79.1 in
Height 1080 mm / 42.5 in
Seat Height 800 mm / 31.5 in
Width 670 mm / 26.4 in
Dry Weight 168 kg / 370 lbs
Rake 24.0 degrees
Trail 96.0mm (3.8 inches)
Fuel Capacity 4.8 gallons, including 0.9-gallon reserve


Configuration Liquid-Cooled, In-Line 4
Valvetrain DOHC 4 valves / cylinder
Displacement 599 cc / 36.6 cu in
Power 61.9 kw / 96.1 bhp @ 12,500 rpm
Torque 53.3 nm / 42.8 ft lbs @ 10,200 rpm
Bore 67 mm / 2.64 in
Stroke 42.5 mm / 1.67 in
Compression Ratio 12.0:1
BHP / Liter 167.0 bhp
Redline 14,500 rpm
Carburetion Programmed Fuel Injection (PGM-FI) with automatic choke; 38mm throttle bodies


Type 6-Speed Constant Mesh
Final Drive 3.018
1st Gear Ratio 2.930
2nd Gear Ratio 2.102
3rd Gear Ratio 1.592
4th Gear Ratio 1.377
5th Gear Ratio 1.190
6th Gear Ratio 1.075

Chassis & Body

Front Suspension Fully Adjustable 43mm HMAS™ cartridge fork
Rear Suspension Fully Adjustable Pro-Link® HMAS Aluminum swingarm
Tire Sizes F 120/70-ZR17
R 180-55-ZR17
Brake Types Cross drilled discs
Brake Size F Dual 296 mm / 11.6 in
R 220 mm / 8.6 in
Available ABS Not Available
Body Material Aluminum alloy - twin-spar


Top Speed 156.0 mph / 251 kph

0 - 30 mph 1.5 seconds
0 - 60 mph 2.8 seconds
0 - 100 mph 6.4 seconds
0 - ¼ mile 10.82 @ 126.93 mph

EPA City / Hwy 34/40 mpg

Let's say your bike now has a 15-tooth front and 45-tooth rear, and you want to drop 1 in front and add 2 in the rear. To do the calculation easily, highlight the expression below, up to and including the "=", copy it, and paste it into Microsoft's Windows Calculator.)

((47 / 14) * (15 / 45) – 1) * 100 = 11.9%

Thus, changing to 14/47 will increase torque in a given gear at given revs by about 12%. And, in a given gear at a given speed, revs will increase by the same 12%. If your bike now turns 6000 RPM in 6th gear at 70 mph, the sprocket change will increase revs by 12% to about 6700.