I’m looking to make my own bike chain lock after seeing some of the ridiculous prices that are being charged for chain locks (upwards of 100 dollars!!).
What I have in mind is using some grade 70 towing chain and something maybe 3/8th to 5/16th of an inch thick. Such chain can withstand tensile forces of over 5000 pounds … which is great if someone were so inclined to pull my bike *and *the rack out the concrete by hitching the chain to their truck or something.
My main concern is the resistance of such chain to bolt cutters. Would such chain be easy to cut with a pair of 48 inch bolt cutters?
Something like this with a nice Master Lock to bring it all together was what I had in mind.
I’ve only ever used a pair of 30" bolt cutters, but it cut through a 3/16" lock like it was butter. I thought the blades must’ve slipped because I hardly felt any resistance at all.
Also, any lock can be cut through with a hacksaw (or a reciprocating saw if they have a bit of money, or an angle grinder, or a drill if the lock is cheap, or…) if the person is dedicated enough. It’s really just opportunistic deterrence, making yours look less appealing than that one over there.
Oh, and lock up your back wheel. There’s nothing stupider than a person with a 10lb kryptonite lock on a bike and the back wheel totally exposed, a couple seconds away from theft.
I had a set of 30" cutters, this dummy locked his work box with a high security lock. We tried my cutters; the shackle was big enough that it wouldn’t fit well in the jaws. Dummy honked down hard and managed to snap off the front third of the jaw. I’m guessing that the shackle on the lock was close to 1/4".
Is this just for at home, or are you going to be dragging many pounds of chain around with you like Marley’s ghost? I doubt bike locks deter any but the most casual of thieves, but if thieves have figured out how to deal with the hardened steel of most bike locks, then towing chain won’t present any additional obstacles.
I recall that I bought some very similar chain recently. You know how they cut it off the bulk reels? They use a big bolt cutter. It didn’t have any trouble with this chain.
It doesn’t do any good to have the chain stronger than the lock or vice versa. A Dremel tool will cost less than 48" bold cutters, and a hacksaw will be pretty cheap also and take only slightly longer to get through.
A big heavy lock and chain might work like The Club if you park with a bunch of other bikes. The crooks will go for the ones with the weakest locks first.