Originally Posted by
repechage
The plastic "bells" were for the CPSC bicycle safety standards introduced in 1976.
They were not mandates per se, the changes made were done to achieve the standards.
Good info. I'd read several references to the 1978 CPSC regulation and did not realize that it was first "promulgated in its entirety" in January 1976 (confirmed at CPSC website). Thanks.
Maybe, as
rootboy points out, since they cause the screw to rust, they are intended to be an indicator of how well the bike is maintained - how often the owner removes and cleans the screw. You know our Federal Gov't is very concerned about maintenance. Maybe I'll bread-wrapper-tie a bag over mine - keep the rain out.