I started the kids on a Peugeot we picked up on a tandem tour in Luxembourg many years ago. Drop bars, calipers, one speed fr. Wheels are about 14" Age 4-5 Next was a Motobecane with 2x3 gearing, drop bars age 5-7 At 8 we found several interesting 24" wheel bikes but most had high bb's and the frames were no lower standover (something that we never considered but customers do quite a bit)than many 650and even many 700c bikes. Twas a time when all Jr racers under 15 (then called Midgets and Intermediates) had to ride 24" wheels. There were some sTrAnGebikes- way high with teensy looking wheels. A Denti we brought back from Italy was close to 40 cm and a very nice Zinn from out west closer to 39. We outfitted bthe Zinn with an allrounder (kinda like a straight with some pull back) and used a dt smooth-shifter (this sounds somuch more positive than friction) on the left and a ratcheted SunTour barconon the right. This bike was the most popular and we eventuallyweened it to drops with bar ends These were the best for the kids- they made it through their entire youth without any STI or Ergo. They've outgrown bikes for the moment and untilthe chil;d brains grow out completely and the adult brains grow in in a few years (20,18,15 now) cycling is relegated to campus cummuting or in the case of the non driver, getting to from lacrosse refereeing( which pays many times what I pay my 15 year olds at the shop.)
When our 'velokids' coach and director took his life many years ago, he left a dozen junior road and track bikes in his estate which we bought from the executor, even though we donated them to him and the program originally.
His own son's bike was in thgere- a gorgeous Guerciotti that was proportionally correct and with the smaller frame. There was a Paris Sport track bike with a 33 cm seat tube that was a favorite and we used for our 5 year old daughter at the time to ride the banks at TTown in the 'egg beater special' event.
The bikes are still in the barn and we loan them on short and long term for the fee of fixing them up and maintaining them before returning for the next kid.
There are also many of the Garden Variety 24's with 45 and above seat tubes that are virtually worthless except for novelty- but with the 650's being built doen to 40cm commercially, what's the big whoop?
The small ones with 'married' head lugs would be the most interesting for collecting.
Larry Black Mt Airy, Md