24" Huffy built western flyer Gravity bike rules used for inspiration http://wgsa.weebly.com/gravity-bike.html general rules all classes 1. Max Weight: 34 Kg / 75 lb.s Max weight is for bike ONLY. 2. Max Wheelbase: 127 cm / 50 in. (front axle center to aft axle center) Stock Speed Bike. No restrictions in Unlimited classes 3. Wheels max Diameter: 51 cm / 20 in. in Stock Speed Bike classes No restrictions in Unlimited Speed Bike classes Design: 3 spoke minimum Wheel Covering: Disk wheel covers are allowed on rear wheels ONLY in stock classes. Both in Unlimited classes allowed. 4. Tyre's: No restrictions MUST be in good condition. 5. Handlebars: Design is open to the builder/rider. Design must prove no danger to rider. 6. Seat: Design and position is open to builder/rider. Design must prove no danger to rider. 7. Foot Pegs: Minimum diameter 3 cm / 1 3/16 in. 8. Ballast: Solid weight ballast is permitted. MUST be secured to the gravity bike frame via structural fasteners or welding. No ballast is permitted to be carried on riders body 9. Frames: Stock Speed Bike classes, only 20" BMX frames are allowed. Unlimited Speed Bike has no restrictions All chassis' and frames must be structurally sound and free of rust and defects. Frames may be either "box" or "round" in design. See bike classes for further verification here. 10. Brakes: All style/design Gravity Bikes must have working front and rear brakes. Disc brakes are HIGHLY recommended, however not mandatory. The basic requirement for any braking system is that the rider MUST be able to bring the Gravity Bike to a full stop, from a speed of 100kph/60mph, within 100m/300ft. Custom braking systems are permitted, however it is up to the rider to prove the braking ability of the custom braking.