Can anyone school me on BMX bikes?

What does he want the BMX for? Offroad or tricks? Worry about the frame. It should be light but strong, graphite being top of the line. Everything else, the brakes, pads, seat, handlebars, peddles, wheels and tires are replaceable.
I would ask Mo about brands, he's probably got idea of what he wants already.

BMX are designed for tricks and stunts - such as jumps, hops, doing wheelies, as shown in the video clip: http://www.youtube.com/watch?feature=endscreen&v=S8kAvITmIek&NR=1

Avoid cheap bikes. Besides the obvious poor performance issues, safety from breakage can put child at risk as failures can cause physical harm.

Helmets ($25-$55), shin guards, gloves and other safety equipt (too often ignored) should be worn. Damage to your skull and/or brain is not happy thing nor is it fashionable.

Some Brands that're Good:
Diamondback

We The People (WTP): models Envy, Zodiac

Eastern (Boss, Reaper)

Cult

Some Brands to Avoid:
Mongoose is to be avoided as they're cheaply made. There are many more...generally they're one that sell for under $300 (new).

Here's an online BMX magazine:
http://www.bmxultra.com/

Here an online BMX forum:
http://www.bmx-forum.com/t/256078/brands-to-avoid-which-ones

More info at this link:

"When you first get into BMX, choosing the right type of BMX bike can be a bit frustrating when you don't know much about what makes a good bike for the money.

Getting into BMX you probably want to search for a bike between the $250-$450 (new) range. $450 USD is a lot of money but it's probably worth it in the long run."

Thank you both!

I ended up winging it since we saw a used one that looked pretty good by a name that had turned up over and over in my research -- Haro.

We had to take it up to the bike shop for a screw to hold the pedal to the crank and they guy said it looked like a great bike and that we'd gotten a great deal on it.

I know that Mo is wanting to learn to work on it and he'll probably want to replace parts and monkey around with it so I'll keep your advice in mind.

Most of the kids use them for street bikes here, which surprised me, since they don't have gears and we have hills -- major hills.

Go figure.

I've seen them used as straight transportation, but I'm not sure they are really suited. It just looks like there is always too big a bend in the knee at the bottom of the stroke, which probably isn't good for the joint.

I know!

They look so uncomfortable. I was worried about joints. I couldn't ride one.

But Mo (and many others) insist they're all the rage.

Older, saner people tell me that a kid gets twice the exercise riding one -- which sounds good to me.

I was really worried about safety with riding such a small bike on city streets but again, I was assured that visibility wasn't a big problem.

Mo rides his bike for transportation about 5 miles a day and an unlimited amount of time for recreation. We live in a very bike friendly city and drivers are very aware of bikes. Plus, I've been careful to map out his route, using safe routes for the busy part and giving him free reign for the calm parts of it.

He's done great on his regular street bike so I'm trusting he'll be equally careful on his BMX.

BMX bikes were originally designed for racing on short, technical dirt circuit inspired by motocross racing, hence the MX in BMX. The racing is dwonright explosive, and the only time the racers sit on their saddles is at the end of the race. The racing is a lot like an out of saddle sprint through out the whole race.

I wasn't sure about BMX on a paved course, but the racing at the Olympics, which in 2012 was the first time for BMX, sold me on it. It was exciting to watch.

https://www.youtube.com/watch?v=_PD6pFByqjs

Freestyle BMX developed when guys like Bob Haro took their BMX bikes and rode them at skateparks. Freestyle is pretty diverse and includes the trick riding shown in the vids that Ragman posted.

Kids don't ride BMX bikes for their appropriatness for commuting, they ride them because, as bomerang said, they're the rage.

The pressure on the knees is ridiculous after a short while riding.

Haro is a venerable brand.

"Can anyone school me on BMX bikes?"

Yo, just say when and where...

Hello Friends,

BMX bikes started it all, back in the late sixties. They were knockoffs of motocross motorcycles and were designed for racing over jumps and around berms in the dirt. Pretty soon kids everywhere had them, racers or not. BMX bikes are still designed for racing, although you don't have to race to enjoy the light weight, speed and dirt worthiness of these machines. They usually have 20-inch wheels (24-inch-wheel "cruisers" are the exception), knobby tires, upright handlebars with crossbars, small saddles, long cranks and rear hand brakes. The frames are light and sturdy, and the higher the price, the lighter they get.
BMX bikes are generally made of chromoly steel or aluminum. Chromoly frames are a bit heavier and more economical. Aluminum frames are lighter and are often made of oversize or exotically shaped tubing. Besides weighing less, aluminum is also rustproof. So, if you scratch your frame, there's no need to rush to touch it up.

Thanks and Regards,
Umang Kumar