CRF's Only Gear - RPM - Speed Calculator

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CRF's Only Motorcylce Gearing, RPM, MPH calculator for Honda CRF450R, CRF450X, CRF250R, CRF250X, CRF150R. Read a step-by-step tutorial on using this calculator.

Please read disclaimer:
The information provided by this gearing calculator is provided "as-is" and without any claim for its accuracy. CRF's Only or YelTrik Motorsports, Inc. is in no way responsible for the accuracy or use of this information. By using this gearing calculator you accept these terms and the responsibility for the use of this information.
All credit for original programming goes to Rob Woods.
Copyright CRF's Only

Need Sprockets?
CRF's Only offers sprockets and chains for the Honda CRF450X, CRF450R, CRF250X, CRF250R, CRF150R.

CRF450R Wide Ratio Transmission:
CRF's Only offers wide-ratio transmissions for the CRF450R.

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Select Honda CRF Model: (choose a CRF model and click 'Load')


Idle RPM:
Max RPM:
Max Torque RPM:
Max Power RPM:
Shift Down RPM:
Shift Up RPM:
Tire Size:	/ /
Tire Size (compare)	/ /
Units:	MPH KPH

Ratios	Driving		Driven	Ratio
Primary Drive:		/			(between crank & clutch)
1st Gear:		/
2nd Gear:		/
3rd Gear:		/
4th Gear:		/
5th Gear:		/
6th Gear:		/
Jackshaft:		/			(not applicable to Honda CRF's)
Final Drive:		/			(stock)
Final (compare)		/

Data by Gear

RPM at xxx by Gear (increment by xxx)

Calculations
Tire Circumference		( Width / 25.4 * Aspect Ratio / 100 + Rim Size / 2 ) * 2 * PI
Tire2 Circumference
overallRatio	=	PrimaryDriveRatio * JackshaftRatio * GearXRatio * FinalDriveRatio
Calculate MPH from EngineRPM
MPH	=	EngineRPM / overallRatio * (TireCircumference/12) * 60/5280
MPH (simplified)	=	EngineRPM / overallRatio * TireCircumference * 0.000946969697
KPH	=	MPH * 1.6
Calculate EngineRPM from knownMPH
EngineRPM	=	KnownMPH * ((5280/60) / (TireCircumference/12)) * overallRatio
EngineRPM (simplified)	=	KnownMPH * 1056 / TireCircumference * overallRatio
EngineRPM for KPH	=	EngineRPM / 1.6

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