Forget the pencil or ruler; use our Center Of Gravity (COG) Stand to accurately measure and adjust the balance point of your pinewood derby car (derby car not included). The built in ruler simplifies the process of finding the exact balance point of your car. Usage With the wheels and axles on the car, balance the car with the rear wheels positioned over the built in ruler. Once the car is balanced on the balance beam read the measurement directly below the rear axles. This measurement is the COG of the car. COG Recommendation Our recommendation for the COG is as follows: Wood Track, no alignment consideration: 1-1/4 inches Wood Track, Rail-Riding: 1 inch Aluminum track, no alignment consideration: 7/8 inch Aluminum track, Rail-Riding: 3/4 inch – Better performance may be attained with a COG closer to the rear axle (5/8 inch or so). However, this reduces front wheel tracking which can result in poor performance near the finish line. So, generally a more aggressive balance point is used when a test track is available to make sure the car will perform properly. To achieve the desired COG, ballast weight must be added behind, and in front of the rear axle. A good starting point for weight placement is 1/3 of the added weight behind the rear axle, and 2/3 of the added weight in front of the rear axle. If needed, weight can also be placed above the rear axle or across the rear axle (using an underbody weight plate). Assembly Required The COG stand comes disassembled. Use a small amount of glue (super glue or epoxy) to attach the balance beam and support members.