I'm curious, how does adding the extension lock to the D-lock make it twice as effective as once you have broken the D lock, the extension will just fall off... The best piece of advice in the video was insurance. The only reason why you lock your bike up then is to fulfil the insurance companies expectations, as you'll never stop a determined thief without a better justice system.

I've had 8 bikes stolen over the last 48 months. Two thefts of 4 bikes each time. GUTTING.

Nicked bikes:

Knolly Delirium T w/Rohloff

Evil Sovereign in Kelly Green with red Rohloff

Verenti Rhigos.01

Charge Juicer Hi

Intense Tazer HT in Red

Cannondale F5000

Scott Aspect 45

Also lost a Foes FXR a few years earlier.

The cable extension is just to secure something like the front wheel to the rest of the frame. It stop someone undoing the quick release and walking off with your £100+ front wheel...

Wow... so much to say here. First, most people don't have mountain bikes with full shocks-- especially in the city, so I don't think that choice of bikes was prime for this demo. A hybrid or road bike with a standard diamond frame would have been much more beneficial. Also, I'll question both the type of lock and locking method.

First, that looked like a very thin U-Lock paired with a very short leash. With a properly thick U-lock, one should lock through the rear triangle of bike thus securing both the frame and most expensive of the two wheels. If you want to use a leash, pop it on the front wheel and connect it to the U-lock as the video shows. That way, both wheels and the frame are locked up. Nothing would be easy pickings. (And if you think that the rear wheel is sufficiently complex to deter its theft, then you haven't changed enough rear-wheel flats on the side of the road nor are you a successful theif.)

The best locking method uses two or more separate locks of differing construction so that a thief would be required to carry a large tool kit to ride of with your bike. I ride with a Kryptonite New York Standard U-lock (used for locking up my rear wheel and frame to the bike rack) and a small Abus chain (for locking my front wheel to my frame and bike rack). Check out this blog page for more information: http://sites.uci.edu/bikeuci/security/parking/

Lastly, if you want real-world parking tips, look up Hal Ruzal and his multiple bike locking evaluations on Youtube (http://www.youtube.com/watch?v=aTA3JsZWiec).