Your definition of 'fringe' is obviously slightly more 'fringe' than mine is. The 7-Eleven team was riding the TdF from 1986 and had a good profile in the US, as did cycling in general through the 80s/90s. Nine American cycling medals at the LA Olympics in 84. Like I said, it might not have been the NFL or NBA, but it simply wasn't 'fringe' in the way you are describing it.
Not sure how olympic medals in a single one off games (five of them were on the track in particular) shows a big interest in cycling. The US won no olympic medals in 1980 (obviously) and 1976 and 1972 and infact you have to go back to the very early days of the olympics in 1912 before you find another US olympic cycling medal winner. Nor did they follow the success of their home games up with just 1 medal in 1988. Of course your argument in a sense is dishonest as I suspect you know perfectly well that the countries that boycotted the 1984 games were traditionally decent cycling countries in the 70s at the olympics. Funnily enough by amazing coincidence the US's number of medals shrank back down in 1988, I wonder why . Then in 1992 at the olympics the medals have followed a different pattern. Apart from that the 1984 US cycling team is famous for doping.
Apart from that the idea that olympic medals means interest in (track) cycling is not something I see. If that had applied here in the past we'd be sorted.