It's a matter of leverage

Tip for August 2008:
How to Make Gearshift/Brake/Directional Levers

The various levers found in most kit interiors are often pretty bad. They're often oversized, with out-of-round cross sections and heavy mold lines. Instead of trying to fix them, you're better off replacing them altogether. Use straight pins for brakes and gearshifts, and wire for directionals. The handles can be created by using round-headed pins, beads, wire insulation, dots of white glue, or multiple layers of paint.