I've began looking into this. It's weird how they use a magnet. Yes it sticks to your frame but like nimhbus says, why not find something cheaper?
I've now discovered the magnet is a lockpicking tool!
I was wondering....

How many bikes have been stolen where there's proof the lock has been broken?
Is the lock left behind?
Are they being picked?

You can use magnets to open car locks so thieves carry them. They maybe marking the bike but it's also one of their tools. Can they use it on bike locks? It can also be used to assist a technique called bumping. A key is slightly modified and can be tapped lightly into the lock to open it!

I don't know what bike locks are safe. I've been looking at my Abus and Krypto keys and bet a lockpicker could get into the locks!

http://www.lockpicking101.com/viewtopic.php?p=222444

Maybe I'm off on a tangent, but something's going on. There's still professional thieves around. :-/

Being environmentally conscious - saving paper ;)

that's interesting...
it would be cheaper for them to use stickers (although they'll get the magnet back when they nick your bike)
i think we might just be being paranoid though. there's a few times i've found little magnets stuck to my stuff, especially my bike. i think it could just be that they're one of the thousands of little metal things that fall off vehicles, etc. and land on the road. however, this time it happened to be a magnetic metal thing and your bike happened to be the only steel thing that it hit on it's way to the floor.
although thieves marking targets is also quite likely. i just don't think you can tell without actually seeing someone do it.
let's fingerprint them and see i they match!! ;-)

Its so funny that the thieves think steel bikes are cool and worth nicking! Ha ha ha. Durrrrr.

Let's face it, this summer there'll be so many clueless cnuts riding round London on 'fixies' that bike thieves will be more than occupied nicking the ones locked through one wheel / around the seatpost etc. to be worried about nicking our properly secured bikes.

This, in tow, will lead to such an oversupply of Charge Plugs / Condor Pistas onto the black market that the arse will fall out of the fixed gear market. Chavs will be hanging around phone boxes and corner shops on said 'fixies' - heck, even Halfords might start selling Condor Bikes in their 'Bike Huts' - and we'll all be posting on Londoncarbonroadies&commuterhybrids.com.

Or something like that...

Is that lifted from your forthcoming editorial for Young Conservatives magazine?

Yeah and I ain't asking you to sub it :p

Just make sure it's all aligned to the right, and they'll love it.

the eco-thief!
the demand for green goods has even stretched as far as the black market these days!

I had a rental car broken into in the US about 10 years ago and that had been tagged with chalk on the bonnet... Police said it was a gang thing, whichever gang tagged it had dibs... Really well organised...
This magnet thing's kinda spooky tho'... I'm locking with two Kryptonites all the time now, right royal PITA carrying those things around... :(

what's a good lock set up then? someone told me to use both a d-lock and a chain lock cuz thieves never carry around tools to unlock both. have we been through this aleady?

I'm thinking about carrying two Krypto mini D's with me, one in each back pocket. I normally carry one and a Krypto cable looped around my waist, with the end stuck into the D-Lock pocket. I can't see another one adding too much weight. And, it'll save faffing with the cable.

But then, sometimes you need a cable with you...

Gah, decisions decisions.

I used to be the proud owner of 5 heavy(ish) duty locks (maybe 6, can't remember) spread around London, I left them places I went so I didn't have to carry them.

I very rarely lock my bike up out of sight anymore.

I lock mine up out of spite.

I use a big Krypto New York through the front wheel/downtube/railing or lamp post and then a Mini-Evo through the back wheel/seat tube... Would be great to be able to lock with two Minis but big clearance/big rims on my front wheel means I have to go large... Bah! :/

There's a big old thread about lock configurations here:
http://londonfgss.com/thread278.html

3rd now...

I think us folks should remember not post links to lock pickers/techniques for stealing. Don't turn this site in to a cycle theft wiki by accident.

If one person knows or cracks the magnet thing don't post exactly how it works :)

I'll ask my 'dodgy' mate next time I see him, he knows about all this kinda stuff...

Security through obscurity never works.

The thieves know these techniques, and the only people who could possibly gain by learning them are those who are attempting to secure their bikes as they will be made aware of the weaknesses of each security device chosen.

Do spread the information on how this stuff is done. As it helps all of us produce counter-measures to try and stay up with or once step ahead of the thieves.

my bike is locked to my heart, those thieves will need a scalpel to steal it.

my bad.but in my defence i was mearly stating in a visual way that D-locks are not the way to go.99% of us on this forum prize our rides,why not splash out nice expensive lock.

2nd now!
behind velorution.

My paranoia extends to a Krypto fagedablahblah mini on frame/rear wheel and a mini evo on front wheel. Whilst in an underground swipe card accessed security guard patrolled car park.

The bumping thing works only on Yale type barrel locks that I've seen demonstrated on Youtube etc. You ram a blank key into the lock at same time as twisting and you possibly can get the lock to rotate if for a fraction of a second the spring loaded bits of the lock are all forced outside the barrel that turns. Much more relevant for home security really.

I've been to Velorution and I doubt we are ever going to beat them.

I suppose I agree with you now. It is an arms race out there and intelligence can help win a war.

or 'bridgestone'

or failing that;

'hipster bike, worth serious moolah, chainset alone lots of ££££££££'

yeah john you hipster cnut! buy a shit bike like the rest of us! :P