I don't know the exact year that mountain bikes became popular, but the first mountain bike I ever saw (and owned) was a Western Flyer Grizzly. It was the epitome of generic, but back then I didn't know what generic was. Evidently Western Flyer bought up other bikes and put their name on them- at least that's what one expert told me. I can't even find a picture of it online to confirm its existence, but you can believe me that it existed. After ramping so many times, the handle bars caved in (That was probably the last time I ramped anything). It was then that I bought a Trek. But The black and green Western Flyer had served its purpose. It got me into biking and survived the Katy Trail in Missouri.
What was your first mountain bike?