Collier Street? Right on my doorstep!
I like the light in these but the focus is a little off - seems the background is more in focus than the riders.
Not too familiar with Sony, but bascially if you can select the centre focus point only (I don't think the Sony's have fast non-centre focus points, but I could be wrong), stick it into continuous focus mode (no idea what Sony call that) and track your subjects in whilst half pressing the shutter release, pushing it all the way down when you want to take the shot.
It looks to me like you've used an area focus mode and its picked up the static things and not the bikes.