CAPTURING A REBEL : A HARLEY DAVIDSON SHAPE GRAMMAR

OBJECTIVE
Develop a shape grammar capable of producing 2-D motorcycle representations that achieve the Harley Davidson look.

ESSENCE AND CHARACTERISTICS OF THE HARLEY DAVIDSON MOTORCYCLE

1. NO COWLING – engine must be fully visible from a side view
2. 45-degree V-engine
3. Large, prominent, finned engine cylinders
4. Low, “Hardtail” frame look
5. Teardrop Gas Tank (regular, Fat Bob, or Peanut)
6. Gas Tank angle shadows angle of the frame’s top tube
7. Have a Primary Drive Transmission component (usually chain-driven)
8. Use chains (or belts) for Final Drive Transmission
9. Have headlight with round/domed profiles when viewed from the front/side
10. Thick, powerful-looking front forks (of various styles: inverted, springer, etc)
11. Generally without Radiators (air-cooled instead)

Additional, “Classic Touches”

1. Thick front fender, with square inner angle
2. Dash Panel mounted atop the fuel tank for speedometer
3. Thick, heavy casting around headlight
4. High-profile, fat tires

SHAPE GRAMMAR EXAMPLES:

There are 48 shape grammar rules in total, below are the first 12.

No input is required. Axr is defined along the Y-axis.

Input: Axf=X coordinate of front axle, this defines the wheelbase

Input: FTid=Front Tire Inner Diameter, FTod=Front Tire Outer Diameter, RTid=Rear Tire Inner Diameter, RTod=Rear Tire Outer Diameter. All values must be greater than zero and od > id. 

Input: T1=upper fork thickness, T2=lower fork thickness, TE=ratio of upper to lower fork segment length, S=height of handles, and R=Rake angle. Only R and TE may equal zero.


Input: X1=left end, X2=right end, G=Ground clearance, T=Thickness. All values must be nonzero. Segment must lie between the tires; (Axr + 0.5?ERTod) < X1 < X2 < (Axf – 0.5?EFTod). 


No input is required.

Tbase=Thickness of Base tube, as defined by designer in rule 5

No input is required.

Alternate to step #6. Assign: S=label for swing arm.

Tbase=Thickness of Base tube, as defined by designer in rule 5


Tbase=Thickness of Base tube, as defined by designer in rule 5



Tbase=Thickness of Base tube, as defined by designer in rule 5