1. Choose Your Bike: The gearing fields will automatically change for you
  2. Enter RPM or speed into green cells.
  3. View results.
800 Drifter   1500 Drifter  
Note, there are additional changeable cells (bottom left) for those who measure speed in KPH and for those whose speedometers are not correct. Vulcan digital speedometers are typically 10% fast from the factory.

Let Engine RPM =


Let Vehicle Speed =

  Primary Reduction (for motorcycles only; use 1.0 for cars)                
      Overall Reduction

Vehicle Speed

  % of max RPM

Engine speed


  Transmission 1st    
  Gear 3rd    
  Ratios 5th    
  Final Drive Reduction              
  Tire Diameter (inches)     Circumference =      
  Engine Redline (RPM)              
  Speedometer Error     (+) If speedo reads fast and (-) if the speedo reads slow  
          Enter (0) to see actual vehicle speeds  
  Units (MPH or KPH)              

Automatic recalculation 

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