Carlos and I celebrated the summer-like weather (75 F) with a short Conzelman loop. We met at the Strauss statue at 3pm and crossed the GGB, fighting lots of tourists. We crossed over Sausalito Lateral and started climbing up Conzelman. I was glad for my fenders because there was lots of run-off on the road's surface. We got to the top, snapped a few pencam photos, and decended down the other side, passing the other old WWII bunkers and the missle base. Continued on through the tunnel, then down Sausalito Lateral, turning back before Sausalito onto Ft. Baker Road to head towards the Discovery Museum. Carlos started having problems with his bike, and we stopped to check, discovering that his cassette was loose on the freehub. Taking things apart revealed that the lockring actually had snapped the threads off of the freehub body. Carlos removed a cassette spacer and reassembled, hoping that the lockring would screw in further and find a better purchase. That lasted for a bout the next 1/2 mile, unfortunately. However, he pedaled gingerly and we made it back across the bridge w/o any more problems.