On Sun, 8 Dec 2019 19:22:23 -0500, Frank Krygowski
wrote:

Seeing Jeff's link
https://www.thegeekycyclist.com/wp-c...e-1024x865.jpg
reminded me:

I spent a lot of time building up a really lovely antique (1960s?)
Italian made mixte for a young lad. He loves it and loves riding. It's a
super-cool bike.

I suspect that "cool" means that none of the other kids have bicycles
that are similar. While conformity to convention is a feature of
growing up, rebellion and going the opposite direction is also
present. I suggest you decide if the recipient is a conformist or a
rebel before building another super-cool bicycle.

But the boy is growing. I've got a couple years to figure it out, but
I'm wondering about what's [going to be?] available that's not a
mountain bike, is reasonably light weight, has multiple speeds, is
fairly kid-proof, and has wheels maybe 24" diameter.

20" BMX is allegedly for 7 to 10 year olds. A longer seat post and
tilting oversized handlebars can make it work for older kids. For a
few years, we had some high skool seniors (17 to 18 years old), riding
around on modified BMX bicycles. The main draw was that they were
suitable for riding in the local skate and bik parks:
https://www.skatein.com/skateparks/united-states/scotts-valley/scotts-valley-skatepark/
http://www.cityofsantacruz.com/government/city-departments/parks-recreation/facilities/bicycle-trip-bike-park

How old is he now?

BMX is available in 24".
https://www.google.com/search?q=bmx+bicycle+24+inch&tbm=isch
You can also get 26" BMX bikes that somewhat resemble mountain bikes,
but retain the hub gearing, coaster brakes, and the inverted kickstand
that doubles as handlebars.

Any recommendations?

Yep. Ask him what he wants to do with the bicycle.
Launch, fly, and crash = 24" BMX
Ride in the dirt and downhill = Mtn bike
Racing = road bike
Traveling = folding bike
Riding to skool = any of the aforementioned

Don't worry about weight. Kids don't care about weight until they
start to sweat.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558