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Why are bike locks so fancy, so specialised?

Would a small padlock, e.g. original Abloy make a good bike lock when connected to a chain?

http://simple.wikipedia.org/wiki/Abloy (first image)

Are there some common attacks that this combination protects particularly poorly from?

Chain may have to be of toughened (motorcycle) variety.

P.S.

Video from Germany testing similar concept with a much heavier lock:

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    Safety is all relative, and depends on where you live. At my office, I see plenty of people with cable locks, even though they are known to be easy to cut, and yet still no bikes have been stolen. Some other places you wouldn't be safe leaving your bike unattended no matter which lock you choose. – Kibbee May 13 '14 at 17:59
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    I think one of the reasons why padlocks are not commonly used is that they are quite heavy and thus may damage the frame/paint job if handled carelessly. – arne May 14 '14 at 6:25
  • Well, they're usually typically significantly weaker than the mini U-locks provided with say, Kryptonite chains, and the weakest part of the system determines the strength of the system. Not to mention chains are often a poor choice due to their massive weight (and 1 or 2 U-locks used properly holds the frame and rim tight to the locking post, when possible). – Batman May 15 '14 at 6:28
  • Chains are resistant to automobile jack attacks -- which if the remainders of bent U-locks and disposed car jacks in my city are any clue -- are one of the primary attack methods here. – RoboKaren Feb 6 '17 at 22:47
  • @RoboKaren that would suggest that one of the best defenses is a strong lock that is uncommon in the particular area. Eg. if U-locks are commonly broken, but there are no chains, take the chain. It is easier to use a second lock of course. – gschenk Feb 7 '17 at 14:42
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+50

The facts are that it is impossible to keep a bike from being stolen by a skilled and/or a determined thief.

I was fairly excited when I saw a bicycle design that actually used the frame as the locking mechanism some time ago. If destroying the locking mechanism means destroying the frame, there is little reward for stealing the bike. However, a friend who is a hobbyist lock pick pointed out to me that few locks are immune to picking or some other method of unintended opening.

Long story short, no method of securing a bike will work against a skilled and determined thief. Most people settle on a method that requires some inconvenience on their part that imparts some amount of security. The methods that are more secure are generally less convenient and vice versa. However, I have yet to see a method of complete security, although I could think of several which would completely eliminate convenience.

The method you describe would still be vulnerable to having the chain cut. With the proliferation of cheap, mostly portable power tools, almost any chain can be cut anywhere in a very short amount of time. Buying a carrying a ridiculously heavy chain might possibly double the amount of time for it to be cut (30 seconds instead of 15!). The weight difference you would have to carry around for that extra 15 seconds should make it beneficial to very few people.

The video you linked makes a big show of using huge bolt cutters. It doesn't bother (deliberately) to bring out a much smaller, more portable and more useful grinder. The below video should give you a better idea.

  • "Buying a carrying a ridiculously heavy chain might possibly double the amount of time for it to be cut (30 seconds instead of 15!)" typically the structures the bike is chained to isn't as tough, and might be cut through in 15 s still. – gschenk Feb 9 '17 at 23:29
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10 seconds with boltcutters- either on the chain or on the padlock, and the thief will have stolen your bike. There are reasons why bike locks are designed the way they are- to stop/prevent this from happening.

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    Not to mention the weight, which is much less of an issue on a motorbike. – alex May 14 '14 at 5:51
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    +1 to the weight of a chain+padlock, difficult to carry just on the bike as well. – AliGibbs May 15 '14 at 7:20
  • I can't vouch for original Abloy brass or brass-covered body (newer padlocks have differen body) surely hard steel shackle cannot be too easy for bolt cutters. Toughened chain should be too, well it's a question of what it was made for. – Dima Tisnek May 15 '14 at 8:05
  • added video link in the question where much heavier lock is tested; lock gets broken by massive boltcutters, chain survives. – Dima Tisnek May 15 '14 at 8:10
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    @qarma, why don't they make locks out of the same material as the chain? – Kibbee May 15 '14 at 13:58

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