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The standard bike lock is a simple U-shaped piece of
hardened steel with a locking cross piece. Hardened
is tough to cut, but modern tools make this much less of
chore than it used to be. For example, a Chinesium angle
grinder complete with cut off disk will get you through a
in less than 5 minutes for <$40. If you want to avoid
sparks and the need for mains electricity, then an
electrohydraulic rebar cutter will chop through in 1
with nothing more than a "thunk". Alternatively, a good
cordless drill can make short work of the lock face-plate
with judicious use of a tungsten carbide bit... the only
downside there is the ferocious self-feed once you break
through to the brass. There's other methods, the
car jack etc. but all the quick methods require
of parts of the lock.
To discourage this, let's make the lock double-walled.
shackle is now steel-void-steel with the walls still being
relatively robust >1mm thick to avoid accidents.
the walls, we fill the void with a liquid. The liquid should
be under significant pressure such that cutting through
outer layer causes a spray through the newly-made hole.
The liquid should get all over the place, especially on the
The choice of liquid is the fun part. Shops have been
clothes with dye-labeled tags for decades, but this isn't a
huge deterrent to the average late-night scumbag so I
propose the addition of a really nasty smelling
putrescine or thioacetone for example. Efforts should be
made to make the liquid sticky and persistent so it hangs
around on any tools/clothes for as long as possible.
If this proves effective then the hardened steel can be
replaced by a tough aluminum since the cut resistance of
steel is no longer required.
[bs0u0155, Oct 22 2018]
[xenzag, Oct 22 2018]
Turns out it's baked : skunk lock
1 bike so equipped stolen : "To avoid the lock, the criminals destroyed the entire bike rack instead." [Loris, Nov 10 2020, last modified Nov 11 2020]
Baked about four years ago...
Write-up from 2016... [kdf, Nov 10 2020]
||Most clever! The thioacetone is a nice touch. You
might even use acid but a spill
would etch the pavement and perhaps harm the
||//spill would etch the pavement and perhaps harm the
||Common bike materials are pretty acid-stable. Phosphoric
acid is a good way of removing rust from steel for example.
Aluminium is easily degraded by common strong acids AND
alkalis in addition to being fatigue prone, so probably not a
good idea to go with pH as your weapon. Incidentally, steel,
titanium, aluminium and even bamboo frames are
completely unaffected by HCN.
||"..and destroying all residues by running them into the
center of a wood fire in a brazier.
||Aha, this explains the spate of brassier-burning on
||[+] I've seen someone cut a U-lock, twice, in less than a minute. But he had the muscles for it, so I wouldn't call it easy.
||My hunch is that, even now, thieves resort to less brute strength methods, such as picking or freezing, which would still go around your clever endeavor.
||I still think my original (of 2008) is a better deterrant than the copy which is a mere smell that's easily avoided with a mask. Try getting away from a swarm of wasps while covered in the substance they love most! (see link)
||Those chancers over at "Skunklock" have robbed my idea
they have! I might chance an email to see what they've got
to say for themselves regarding the originality of their
||"Those chancers over at 'Skunklock' have robbed my idea they
-bs0u0155, Nov 10 2020
||Skunklock has been available since 2016, two years before
your posting here.
||I posted my bleeding lock idea in 2008. Original is
||Yes, I was going to mention that after checking for other prior
art. Xenzag seems to have priority here ... though there might
be earlier references to similarly booby-trapped bike locks that
I haven't come across yet
||Bugger, getting there first is actually the most offensive
kind of theft. My only innovation then, is putting
thioacetone inside, which frankly is a workplace accident
lawsuit waiting to happen.
||For every lock, there's a workable flaw. But with any gaining of knowledge, let others* make the initial smelly mistakes.