Originally Posted by TerryK
There is no shower at SFO RCC either.
There was a thread where someone claimed to be able to access Koru Club while connecting to UA by sweet talking through security. There are nice showers in Koru Club. The trouble is that it is in T2, you need to go to the opposite sides of the airport and go through security twice, in addition to sweet talking TSA to let you through without proper boarding pass.
...and also sweet-talk your way past the lounge receptionist (who hopefully won't call security on you).
The only showers available in SFO are in the SQ SKL. However, that is in the International Terminal, which you won't be able to access. So the short answer is no. You won't be getting much either from SFO.