Super Bike Suspension Geometry

 Front suspension geometry is defined by the following six variables which are defined as:

    • Offset-- Centerline of top of steering neck to centerline of top of fork tubes.
    • Rake (Castor) -- The angle in degrees of the steering neck from the vertical.
    • Fork Length-- The distance between the top of the fork tubes to the centerline of the axle.
    • Diameter of the front tire.
    • Diameter of the rear tire.
    • Trail: Distance defined by vertical line from axle to ground and intersect of centerline of steering neck and ground.
    • Raked Triple Trees-- In order to bring trail figures back into line, triple trees with raked steering stems can be used. Expressed in degrees. Usually adjustable in degrees of rake (castor).
 

Rake and Trail Front Geometry Calculator

Wheelbase inches Wheelbase. Conservative settings for stability 55.9 inches (1420mm) Weight @ 52/48%
Rear Tire Diameter inches Diameter of rear tire. (Use rolling radius times 2)
Front Tire Diameter inches Diameter of front tire. (Use rolling radius times 2)
Beginning Castor degrees Steering Rake (Castor).
Conservative settings - Castor @ 24 deg .
Triple Clamp Offset inches Distance from center of top of steering neck to centerline of top of fork tubes. Typically 1.023 to 1.102 (26-28mm)
 Fork Length inches Length from to top of the fork tubes to the centerline of the axle.
Ohlins FG370 - 28.740 inches (730mm)  Ohlins FG670 - 28.120 - 29.1 (714 - 740) Special Order
Triple Tree Rake degrees For standard triple trees enter 0 degrees. - Special use raked trees. 
Offset Std.__________________________
Special Offsets_______________________
New Fork Length inches Length from to top of triple tree to the centerline of the axle.
Enter the new length in inches.
Note: Trail cannot be a negative number.
Unless you are building an 180 MPH, Ohlins Equip, shopping cart. Typical Sport Bike trail figures
are between 3.5 and 4.2 inches. 
 (95.30 - 104.0mm)
Fork Angle (Castor) in degrees
Trail in inches
Rear axle centerline to centerline top of fork tubes, inches
Rear axle centerline to front axle centerline, inches
Top of fork tube centerline to ground, inches
New Geometry Figures From New Fork length
New Fork Angle (Castor) in degrees
New Steering Neck Angle in degrees - if change in Triple Tree Rake
Trail in inches
Wheelbase in inches
Rear axle centerline to top of  forks centerline, inches
Rear axle centerline to front axle, inches
Top of fork tube centerline to ground, inches