Cutting this groove is difficult to do by hand, but it can be done with an axle file. Our grooved Speed Axles and Pro Super Speed axles have this groove, exclusive to Pinewood Pro, cut directly under the axle head.Pinewood DerbyTips & HintsThe best part of pinewood derby is designing a unique, cool car that you can call your own. Don't worry about aerodynamics because it is almost insignificant. We identify dozens of other speed tips in Winning Pinewood Derby Secrets that rank far above aerodynamics.Pinewood Derbydesign TipLooking for more cool car design ideas? Our free Pinewood Derby Car Design Guide has over 100 cool pinewood derby car design ideas.Pinewood Derbyrules HintBSA Rules are different from Awana Rules, which are different from Adult Race Rules, etc. Check our Pinewood Derby Rules page to download Pinewood Derby rules for different kinds of races.It was my son's first Kubcar race...approx 60 cars, and he took 1st place! He was so excited... Thanks again. Your Winning Pinewood Derby Secrets book really helped more... See more text