When I'm riding my "good" bike, I lock the frame and a wheel (usually rear) to something very fixed. I then *separately* lock both wheels and the frame to the same thing. I do this because, based on what I've heard, most bike thieves carry either the tool to cut a U-Lock or the tool to cut a cable, but not both. I wouldn't do what the pic shows b/c if the U-Lock is compromised, the bike is gone.

I've not tried locking the U-Lock through the rear wheel, but here's a (trusted by me) source which suggests its safe: http://www.sheldonbrown.com/lock-strategy.html.

As far as cable combo v cable key, I have a cable combo for short trips (e.g. bike in high traffic area for 10 minutes or less). I understand that there really isn't any difference in security between the 2.

Carrie Anne