TIP: make your own security chain for cheap

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TIP: make your own security chain for cheap
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Posted: May 3, 2010 at 0:18 Quote
I can't take complete credit for this as I saw it suggested somewhere else, but I'd like to share what I learned. Apologies to non-USA readers for the archaic US measurement system.

I started out using a cable and regular 3/8" Master Lock for bike security during food stops on the road and even an occasional overnight motel stay. That didn't make me very comfortable, especially after watching videos of bolt cutters going through the same size Master Lock with ease, and that doesn't even address the cable weakness. I did some research and found that even the most expensive hex or square link Kryptonite chain can be defeated with the right bolt cutters. One video showed a guy with 6 foot bolt cutters (!!!) cutting the top-end Kryptonite chain using his weight and the concrete floor as a backing. A determined thief, especially one with exotic tools, will not be stopped. So what is the highest probable (and reasonable) threat you will face? The answer I came up with for myself was a hacksaw or 36" bolt cutters in "field conditions." Field conditions means your bike is locked up in a way that prevents bolt cutters or a hacksaw from being used in optimum position.

A good chain should meet the above standard, but Kryptonite chain is VERY expensive for just a short section, as are the rest of the marketed security chains. Grade 70 transport chain is a high strength alloy and is very close in toughness, but much cheaper. This chain is common in the US and can be identified by the term "Grade 70" and the typical gold color. The 5/16" size can BARELY be cut by 36" bolt cutters with a 180lb guy bouncing all his weight on the handle for about 20-30 seconds, including 1 or 2 chain repositions. Take away these ideal conditions and it becomes much tougher, if not impossible. The 3/8" chain size should be impossible to cut with all bolt cutters of common sizes no matter what the conditions. Hacksaws can cut this chain, but it requires the chain to be in a vise, and you to have a lot of patience. This is how they cut it at hardware stores, and the employees are not happy afterwards. The easiest way to cut this chain is with a grinder or torch, which is what I recommend if you want to split up a longer section.

To cover the chain, simply pull an old tube over it. You will need at least a 2.1" tube for the 5/16" chain and a 2.3" or bigger tube for the 3/8" chain. I wrapped black duct tape over the ends to secure the tube and cover the last exposed link. I also used tape to anchor two tubes together on a long section of chain.

How much does it cost? Here in the US, you can get the 5/16" version in a 20 foot length for about $35 at Harbor Freight, Tractor Supply, or Northern Tool. Hardware stores usually carry it by the foot, but expect to pay a little more. The 3/8" version is harder to find and will cost you double. Tractor Supply had a 20 foot section for $70. That may sound expensive until you price out any comparable "security chain" of that size and length. You can save money by splitting one of the long chains with friends.

Don't forget the lock! Standard 3/8" locks are POOR performers. I recommend getting a lock with at least a 7/16" shackle or a 3/8" lock that has been verified to be a high performer.

I wish I had done this first as I could have had a tough chain for the same price that I paid for a couple cables!


Posted: May 3, 2010 at 0:46 Quote
coil-n-oil wrote:
I can't take complete credit for this as I saw it suggested somewhere else, but I'd like to share what I learned. Apologies to non-USA readers for the archaic US measurement system.

I started out using a cable and regular 3/8" Master Lock for bike security during food stops on the road and even an occasional overnight motel stay. That didn't make me very comfortable, especially after watching videos of bolt cutters going through the same size Master Lock with ease, and that doesn't even address the cable weakness. I did some research and found that even the most expensive hex or square link Kryptonite chain can be defeated with the right bolt cutters. One video showed a guy with 6 foot bolt cutters (!!!) cutting the top-end Kryptonite chain using his weight and the concrete floor as a backing. A determined thief, especially one with exotic tools, will not be stopped. So what is the highest probable (and reasonable) threat you will face? The answer I came up with for myself was a hacksaw or 36" bolt cutters in "field conditions." Field conditions means your bike is locked up in a way that prevents bolt cutters or a hacksaw from being used in optimum position.

A good chain should meet the above standard, but Kryptonite chain is VERY expensive for just a short section, as are the rest of the marketed security chains. Grade 70 transport chain is a high strength alloy and is very close in toughness, but much cheaper. This chain is common in the US and can be identified by the term "Grade 70" and the typical gold color. The 5/16" size can BARELY be cut by 36" bolt cutters with a 180lb guy bouncing all his weight on the handle for about 20-30 seconds, including 1 or 2 chain repositions. Take away these ideal conditions and it becomes much tougher, if not impossible. The 3/8" chain size should be impossible to cut with all bolt cutters of common sizes no matter what the conditions. Hacksaws can cut this chain, but it requires the chain to be in a vise, and you to have a lot of patience. This is how they cut it at hardware stores, and the employees are not happy afterwards. The easiest way to cut this chain is with a grinder or torch, which is what I recommend if you want to split up a longer section.

To cover the chain, simply pull an old tube over it. You will need at least a 2.1" tube for the 5/16" chain and a 2.3" or bigger tube for the 3/8" chain. I wrapped black duct tape over the ends to secure the tube and cover the last exposed link. I also used tape to anchor two tubes together on a long section of chain.

How much does it cost? Here in the US, you can get the 5/16" version in a 20 foot length for about $35 at Harbor Freight, Tractor Supply, or Northern Tool. Hardware stores usually carry it by the foot, but expect to pay a little more. The 3/8" version is harder to find and will cost you double. Tractor Supply had a 20 foot section for $70. That may sound expensive until you price out any comparable "security chain" of that size and length. You can save money by splitting one of the long chains with friends.

Don't forget the lock! Standard 3/8" locks are POOR performers. I recommend getting a lock with at least a 7/16" shackle or a 3/8" lock that has been verified to be a high performer.

I wish I had done this first as I could have had a tough chain for the same price that I paid for a couple cables!


That's a nice little idea. I was actually thinking of sending to Britain for an Almax chain and a CISA or Squire padlock. Super expensive but looks like it's impossible to cut with a bolt cutter. Being a former locksmith I can say that it's not just the chain you have to worry about. What's really needed is a lock with a shrouded shackle or the baddies will just target that.

I used to laugh when people had me out on a service call to undo a chain. It was always some big ugly chain secured with a $5.00 padlock that could be opened with a sharp rap from a small hammer or rock.

Also, as a locksmith, time was money and many times it was more cost effective to cut a lock off in a second or two and replace it then it was to pick it or use other methods. The scary thing is bolt cutters are fast, cheap and anyone can purchase them and keep them stashed and quickly retrieve them. A thief is much less likely to use a hacksaw or grinder as it's more noise and exposure over a longer period of time. It only takes a second to use a set of bolt cutters and toss the bike in the back of a truck and be off.

You don't have a bad idea there. Although, I will say that any chain that isn't properly hardened straight through will cut like butter. Even large diameter chains can be nibbled at with cutters in just a few seconds until broken through. I was impressed by that Almax chain though. It's pretty heavy for a 70cm length but I sure like that it can't be cut with bolt cutters.


http://www.youtube.com/v/VC3hFr8p2ck

Posted: May 3, 2010 at 1:03 Quote
rottenguy wrote:
The scary thing is bolt cutters are fast, cheap and anyone can purchase them and keep them stashed and quickly retrieve them. A thief is much less likely to use a hacksaw or grinder as it's more noise and exposure over a longer period of time. It only takes a second to use a set of bolt cutters and toss the bike in the back of a truck and be off.

That's exactly what I ended up realizing. I am looking to avoid the quick bolt cutter snatch. A grinder will get through anything so there's no need to cater to that concern.

Pick up a short test section of that 5/16" chain and have at it with your bolt cutters. See if it impresses you, or at least makes you break a sweat. I'd like to see the bolt cutters that can tackle the 3/8" chain.

Posted: May 3, 2010 at 18:49 Quote
coil-n-oil wrote:
rottenguy wrote:
The scary thing is bolt cutters are fast, cheap and anyone can purchase them and keep them stashed and quickly retrieve them. A thief is much less likely to use a hacksaw or grinder as it's more noise and exposure over a longer period of time. It only takes a second to use a set of bolt cutters and toss the bike in the back of a truck and be off.

That's exactly what I ended up realizing. I am looking to avoid the quick bolt cutter snatch. A grinder will get through anything so there's no need to cater to that concern.

Pick up a short test section of that 5/16" chain and have at it with your bolt cutters. See if it impresses you, or at least makes you break a sweat. I'd like to see the bolt cutters that can tackle the 3/8" chain.

Don't get me wrong. I think it's a reasonably good alternative. I like the idea of the tube as well for scratch protection. The cost of the hard to cut or impossible to cut chains is pretty high and somewhat prohibitive.

I think it's a matter of priorities and what you stand to lose as well. No one should be riding around on an expensive bike with high end components and leave it for very long. I think there is a happy medium there. You can have a decent bike with a very good chain but if you want to be reasonably secure you don't stop there.

Really you need locking skewers, seat post clamp, chain or cable around seat post rails secured to the frame or seat post clamp. You may also want to look in to locking bolts for your brakes and headset as well as these can be slipped off with an allen key in no time.

I'm in the process of setting my hard tail up as an urban bike like this so I can feel free to leave it for short periods of time when I go in to stores and such. I still don't think I would leave it for hours in the same location on a schedule as some parts might still get nicked or some petty thief might bugger the lock to be a dick if he can't steal it.

This may sound like an awful lot of effort and money. But I think I would rather go this route then walk out and find my poorly secured bike gone or have parts stripped off of it and have to shell money out for replacement. It would provide a little peace of mind. To me that's worth quite a bit as I tend to worry about things quite a bit.

Posted: Apr 24, 2013 at 11:38 Quote
I can see what your trying to get at , I don't want to sound negative as I can see you have put in allot of thought to the security chain but have you thought about hacksawing as this is another relatively quiet attack.

For an anti bolt cutter chain you don't have to go up to a massive chain, consider the squire 14mm chain as this is the smallest guaranteed not to be bolt cut and nice and portable @ 4Kgs for a 1.2m.

Worth a mention is to actually wrap the chain around something immovable as a chain just locked to a bike is as much use as a disk lock, seen this way to many times.

Id bung in a link to the squire but may get an admin prod lul.

Posted: Jun 10, 2013 at 8:22 Quote
I'd like to say, great article coil-n-oil!

coil-n-oil wrote:
...Grade 70 transport chain is a high strength alloy and is very close in toughness, but much cheaper.


I just wanted to make a correction here. After reading your article and doing a little research on the chain you recommended, I found that Grade 70 transport chain is a high strength, carbon chain; not an alloy chain.

Alloy chains have higher maximum working loads, higher melt points, and require a higher amount of force to break than equivalent thickness carbon chains. This isn't to say that Grade 70 Transport chain is bad to use; I simply wanted to clarify this so that people who are looking for maximum security aren't misinformed. Most high end padlocks and bike locks (e.g. Kryptonite) are made using alloy metals rather than carbon metals (mostly because the thickness of the shackle is often smaller than the thickness of the chain or anchor it is securing, and thus must make up for the loss in strength by using a material with a higher strength to weight ratio).

I found a document online (unsure of it's credibility):
https://law.resource.org/pub/us/cfr/ibr/004/nacm.steel.chain.2003.pdf

It states on page 3:
"Grade 80 Alloy Chain - Premium quality, high strength alloy chain, heat treated, used in a variety
of sling and tie down applications. For overhead lifting applications, only
Alloy Chain should be used.
Grade 70 Transport Chain - A high quality, high strength carbon steel chain used for load
securement. Not to be used in overhead lifting"


I also found a site which lists the maximum strengths of each chain grade.
Note: This site is somewhat poorly designed. You can find the links to each chain grade's specifications in the center of the page, at this link.
http://www.tulsachain.com/chain_WLL_chart.asp


A note of caution to anyone looking for a security chain: The specifications for chain grade's leave a good amount of control in the chain manufacturer's hands, as far as the materials to be used in the making of the steel used for the chain. Not all manufacturers use the same materials or the same process for making a chain (or any kind of metal object); which means, from what I understand, that it is very possible for two chains of the same grade (created by two different manufacturers) to have different maximum strengths, different melting points, different sheer strengths, different reactions to chemicals, etc. So make sure you buy from a trusted company or manufacturer (it may cost a little more, but if you're concerned about security, the ease of mind will be worth it).

The specifications for alloy and carbon chains, according the document in the first link I posted, are as follow:
"4.1 Material – Carbon Chain
The selection of the base steel is left to the judgment of the individual chain manufacturer provided the
steel meets the following criteria: Carbon, 0.35% max.; Phosphorous, 0.040% max.; and Sulfur, 0.050%
max.
4.2 Material – Alloy Chain
The selection and amounts of the alloying elements in the steel are left to the judgment of the individual
chain manufacturer provided the steel meets the following criteria: Carbon, 0.35% max.; Phosphorous,
0.035% max.; Sulfur, 0.040% max. Nickel must be present in an alloying amount (0.40% min.), and at
least one of the following elements must be present in an alloying amount: Chromium (0.40% min.) or
Molybdenum (0.15% min.)."


I hope this post was helpful to someone out there.

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