In the early 90s, Schwinn made Paramounts in both 700c and 650c versions produced by both Waterford and Panasonic.
Also, some smaller frames use 650c to minimize toe-lap problems encountered with 700c.
I think one reason they never caught on is that on a larger frame they make the bike look like a circus clown should be riding it.
Originally Posted by Schwinn 1992 Paramount catalog
The Case for 26” Wheels
Ask Product Manager and Cat II racer Dennis Lane why you should consider switching to 26” wheels and he’ll tell you the real question is why anyone still rides 700C in the first place.
“I’ve ridden a Series 7 prototype for the past two seasons,” he explains, “and the 26” wheels are faster in every respect.”
“Of course there’s less wind resistance with 26. And they’re lighter and stronger because the spokes are shorter. And the reduced gyroscopic force lets the bike change lines quicker, making it more maneuverable. And because they’re smaller and weigh less, they accelerate faster. Those are all points people pick up on right away in a test ride.”
“But what really sells them is the first time they ride in a pack. They can’t believe it! They’re motoring along at 25 or 30 mph, and realize they’re doing a lot less work – every time they jump it’s an instant bike length on the nearest rider. By the end of the race, they’re lifetime converts.”