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Short Summary
Main recommendation: To maximize a pinewood derby car's speed, max out its weight at five ounces and place that mass about one inch in front of the rear axle, then use a streamlined shape, ride on three wheels, lighten the wheels, and use bent, polished axles with graphite. Mark Rober's "rail rider technique" (steering the car so it maintains light contact with the center guide rail) and canted wheels were also presented as winning traits, based on his research and conversations with adult pinewood derby league experts. Rober's 45-minute car built on these principles beat a 12-hour expert-built car in a test run.
Key Points
- Weight placement matters most: maxing weight at five ounces and placing it toward the rear contributed about 36% of the speed advantage in Scott Acton's testing; the worst placement (at the very front) lost to the best by almost five car lengths.
- Light wheels rank next, worth about two car lengths, with weight removed especially from the outer edges of the wheels.
- Polished axles beat normal axles by about 1.3 car lengths, while grooved axles were a waste of time and money.
- Reducing the car to three wheels beats four wheels by about 1.1 car lengths, and graphite adds about 0.9 car lengths against an ungraphited car.
- Rail riding and canted (bent) axles were not tested by Acton; Rober researched and implemented them himself after adult pinewood derby league organizers told him that winning and competitive cars commonly rode on three wheels, rail rode, and had canted wheels.
Details Worth Noting
- Concrete instructions:
- Keep total weight at the five-ounce maximum.
- Place the center of mass about 0.9 to 1.5 inches in front of the rear axle, and about one inch in front of the rear axle in Rober's build. Balance it by using duct tape on the line drawn at that spot.
- Make one cut in the block to reduce its profile for a simple streamlined shape; don't overdo aerodynamics.
- Polish axles by chucking each nail in a drill press or hand drill, duct-taping the trigger down, and working through sandpaper grits (from about 600 grit) with water, finishing with a polishing compound.
- Mark the 12 o'clock position on the nail head before polishing.
- Bend axles to about 2.5 degrees using a bending tool, or buy pre-bent, pre-polished axles online.
- Lift one wheel off the ground by deepening one side of the front axle groove so the car rides on three wheels.
- Apply graphite generously to wheels and axles; over-application is not a concern.
- For rail riding, use a flat board four to six feet long; set the car so it leans about one inch toward the raised-wheel side, then twist the nail head to fine-tune. Check that rear wheels migrate outward, leaving a little daylight between wheel and body, and twist the axle head with pliers if needed.
- Rober said that prized "graphite" brands showed no meaningful difference from one another in his independent tests.
- Grooved axles provided no measurable benefit because friction depends on the materials and the weight pressing on the surface, not surface area.
- Acton's full testing is in a separate roughly two-hour video with further detail on fabrication.
- Rober's full build took about 45 minutes; in an informal post-race test, his 45-minute car beat Mason's 12-hour expert-built car in a head-to-head run.
Bottom Line
Mass placement and weight account for the biggest speed gains, while low-cost measures like polished axles, graphite, and three-wheel riding add meaningful advantages without much time investment.
