ShawnF has some great advice! I’m with him on everything he said, especially the websites and helmets.
My back story: I began racing BMX in 1981 in Australia, fell in love with it, and have never stopped loving it.
State-of-the-art is a right-size aluminum frame, right-size handlebars, 20 x 1 1/8 or 1 3/8" wheels and tires, three-piece cranks, and a uni seat or pivotal seat post with a small plastic seat. Carbon fiber is just creeping into BMX. Titanium still exists for young riders whose parents are willing to pay for it. For tires, you don’t run Comp IIIs anymore. Nowadays, tires are almost like slicks. Tioga and Vee are what you see most.
I concur with bike and safety gear costs. It’s 10% what it costs for triathlon and a welcome change! Some tracks have sell and swap nights. Otherwise, see where they recommend you buy a second-hand bike. GT and SE Racing are two other longstanding brands that still offer new completes for good prices.
Don’t skimp on the full-face helmet. Tracks have changed a lot. They are filled with big jumps and rhythm sections – that younger riders just roll over – and almost all have tarmac turns.
There are rules for number plates – white background and black numbers, for example. Read the USA BMX rulebook. There’s also a shift to flat pedals for not just beginners, but younger racers. I think that in 2021, everyone 12 and under will run flats.
Club days and nights are still great fun. There is a beautiful family atmosphere. With BMX, you spend a lot of time hanging out.
USA BMX does a good job licensing riders, coordinating with track operators, tallying points, and offering prizes at local, regional, and national levels. Their magazine, which comes free with a membership, is a bible for young racers. There are a lot of adults who volunteer a lot of time to make tracks smooth-running and, at a higher level, fund and run racing teams.
Online, you’ll see many complaints about USA BMX. The only thing you hear at your local track is parents suggesting competent riders step up and race regionals and nationals.
I hope this helps. I’m stoked if I can help someone whose posts on aerodynamics and bike fit have been valuable to me.