I have a Vista 10 speed conversion, circa late 70s early 80s. The bottom bracket has a threadless spindle design: two cups that hold the bearings in, spindle "pegs" that attach to the cranks. Fair enough. The problem here is that they keep gradually loosening over time. I took it apart, regreased everything, put it back together. It ran fine for a ride or two but it's loose again. There is no lock ring

I'm a bit confused by the lack of a lock ring, nothing was lost in the conversion. Which means: the bike either didn't have a lock ring when I got it (it was lost) or the bottom bracket never had a lock ring. The former seems more likely (I didn't loose anything).

Anyway, I have a new chainring/crankset I wanted to put on there anyway but the bottom bracket on the frame isn't threaded. Are there any new square taper bottom brackets that this frame type will accept?