not too hard to get too
With some some patience you can get there on public transit. Take muni bus 19 from downtown/civic center (8th & market) heading south. It will take 30-40 min to get to the stop right in front of the brewery (Evans Ave & Keith St). I would recommend asking the driver to stop there when you get on or after you cross 3rd St.
The bus does go through some of SF's more colorful neighborhoods, and passes by the county jail, SF general hospital, and loops through a housing project on potrero hill, but being on the bus is safe. Avoid looking too touristy and playing with expensive electronics or cameras while on the ride and you should be fine.
I've been out to Speakeasy on Fridays afternoons when they have tastings. For $3 you get a pint, they often have new beers you can't yet buy, and local families come in with tasty food to sell. A SF must in my book!