BMX Parts sells BMX Parts of almost every brand. ACE has Frames, Forks, Headsets, Stems, Brakes, Cranks, Sprockets, Pedals, Chains, Freewheels, Wheels, Tires, Tubes, Pivotal Seats, Railed Seats, Old School Seats,  Pivotal Seatposts, Railed Seatposts, Seatpost Clamps. In fact there are about 23 different parts that make a complete a bike. It takes special bicycle tools and mechanical skills to assemble one from scratch. You will need to learn about the different sizes and which parts are designed to fit with other bike types. Check this webpage that is a search for popular BMX products.

Old School BMX Bike Example 1

The main difference between old school bikes and new ones it the headset and cranks BB sizing.
Old school bikes use a 1″ threaded fork with a 1″ threaded headset. Old school bikes have a 2″ bottom bracket shell so they take an American size Bottom bracket bearing and cup combination. The common gear ration on a old school 20″ wheeled bike is 44T:16T. If you want to get out of the gate faster you run a 43T for example. View the Specs of this Hutch bike

BMX Parts on Old School Retro Hutch
Owners Hutch BMX Custom Bike

New School BMX Bike Example 2

Kink 2019 Gap XL Gloss Trans Deep Purple Edge Fade
Kink Gap XL

New school BMX bikes use a 1 1/8″ threadless fork with a 1 1/8″ threadless headset. New school bikes have a slightly small mid bottom bracket shell so they take a Mid size Bottom bracket bearing and cup combination. The Mid BB is equal to the American BB size without the Cup that holds the bearing. New school bikes use a 25T:9T gearing and often have a 14mm rear axle and a 3/8″ front axle. With riders running their bikes a little harder and adding pegs the thicker stronger 14mm rear axle became the adopted axle specification. The pedaling ratio is the same when pedaling but appears much different.  These New School bikes have the same size rims but riders are preferring much wider freestyle Tires.

Can you help us make some videos? Checkout this BMX Videos on Youtube