Backpack Zipper Security
From a security standpoint, second to leaving our backpack unattended and unsecured, the zipper is generally the weakest point. An unlocked zipper allows entry into your pack and access to it's contents, even when on your back.
Some mini cable locks can be threaded through the back of most backpack zippers where the zipper pulls are attached
This allows you to lock most reasonably sized zippers without modification
To make zipper entry less desirable to the opportunist thief, you have several options, such as padlocking, ziptieing (use of a cable tie) or even securing your zippers with a snap-link or clasp. It is important to note that these precautions are only meant to slow or deter a thief and do not guaranty theft protection.
Padlock Sliders with Multiple Locking Tabs
Snap links and clasps can be undone, zipties can be cut and locks can be picked, decoded, and even cut. And even if you you have what seems like a very secure zipper setup, a motivated thief can often open a zipper with a simple ball point pen.
Locking zipper pulls close to zipper slider allows less play than placing lock at ends of zipper pull
A metal ring or loop at the end of the zipper allows you to secure single and double pull zipper sliders
A locked zipper can often be opened without tools by pulling opposing edges apart where locked zipper sliders meet each other or the end of the zipper. The closer the slider ends are from opposing sliders or the end of the zipper, the more difficult it is to gain access to the pack. That said, locking the outer ends of a zipper pull is less secure than locking the inner holes of zipper pulls, which is less secure than locking zipper sliders designed for padlocks.
Pacsafe bag with snapping hooks for securing zipper pulls
S-Biner holding zipper pulls together
Zippers with only a single slider can be locked by adding a D-ring or fabric loop (with or without a metal core) at the closed end of the zipper and locking the slider to this. You can also use a snap-link or clasp of some design to allow for securing your slider to the end of the zipper without needing to fumble with a combo or key. A simple snap-link closure is easily defeated, but can deter against pickpockets - especially when using a link with a threaded lock and/or when the link is hidden out of site (under a flap).
GooglePatents US7073233 zipper buckle
Padlock Zipper Slider
with single locking tab
Hasp Padlock Zipper Slider
If you are using a backpack without lockable zipper sliders, you can retrofit your pack with updated sliders. Lockable zipper sliders can be purchased from luggage repair specialty shops (such as Ohio Travel Bag or hardwareelf), homemade or salvaged from luggage (try Goodwill or thrift shops). Replacing zipper sliders isn't that difficult, but it does require a little finesse and a little fiddling to get everything lined up just right.
Padlock Sliders with Single Locking Tab
Zipper separation with long shackled lock
A sleeve could be added to the shackle to allow for a tight fit
A Cable lock can allow for a lot of play between zipper slider
It would be easy to pull zipper apart and fit hand in this bag.
Note that when choosing a padlock sliders design that sliders with single tabs tend to be more durable than those with multiple tabs, but can allow for enough separation of the zipper to be a problem. It only takes a small opening between the sliders to allow sticky fingers access to your pack and allow them to make an opening where the sliders meet. Lengthy shackles as well as those with skinning shackles allow for greater zipper separation.
If you are crafty, you can make your own lockable zipper sliders. DIY zipper sliders include:
String stainless steel wire through and around the top of your slider to secure and form a metal ring. reinforce with glue, epoxy, solder or a good rap or wire
Braze on a piece of metal with a hole drilled in it.
Braze on metal wire bent in a loop
Make shackle with formed epoxy with hole drilled through
Build metal bracket to fit over slider - secure to slider with solder, mini bolt, epoxy or via zipper pull
If you decide on making your own lockable zipper, you will find that making a securable zipper pull is much easier than making a securable zipper slider. See below for ideas on how to make a lockable zipper slider.
Padlock Hasp Zipper Sliders
Padlock sliders with a hasp design tend to be pretty sturdy in design, but tend to jingle quite a bit when not locked. It is difficult to pad these zipper pulls and still allow for the hasp to function properly and may be better suited for packs that are to be locked when in transport. They may not be ideal for daypacks, unless they are always locked when worn or if the little jingle doesn't bother you.
Keyed Hasp Lockable Zipper Slider
Keyed Lockable Zipper Slider
Sliders with a built in locks can usually be easily picked with a paperclip and the keys may of course be easily lost. Ones with the lock built directly into the slider generally force a tooth into the zipper and prevents the zipper from being fed through the slider.
If you are not able to use or install a locking zipper slider, you can make a lockable zipper pull out of stainless cable (either coated in vinyl or small cord) and crimp it to your slider. If you make a long zipper pull, you can add an extra crimp in the middle of the pull to allow for a usable length pull and a tight lock. With a bit of work, metal cable can also be sew together to avoid need for a crimp.
Zipper pull made from Steel Cable
Lockable Zipper Pull options:
Plastic Zip Tie
Metal cable (connect at end or in middle to create double loops) -
use metal crimp (crimper, swager, Swage-It Tool):
Aluminum Crimp Sleeves
Mini Double Barrel Copper Sleeves - fancy tackle supply shop
Stainless Steel Crimp Sleeves
Metal sleeve filled with epoxy or soldered
Zipper Pull plastic cap filled with Epoxy/glue
StructSure Aerohead eu.itwnexus.com/content/structsure-aerohead-1
Eyehook clamp - carolinawildphoto.com footcable
Telephone Wire Connector instructables Wire-Zipper-Slider-Handle
Vktech Stainless Steel Wire Keychain Cable
secured with epoxy, tape, solder, etc
thread and slide cord or tube around keyring - glue, sew or ignore ends. Loose ends can be covered with cord pull tab sew or glued over them
Metal cable encased in hollow core nylon cord. Secure by:
sewing end with braided thread
using a zipper pull cap (with or without glue)
soldering end together
using metal sleeve - crimp or fill with epoxy/solder
pull tab end made from epoxy
Metal ring -
Secure with ziptie, chain link, cord, multiple wraps of thread.
Split ring - attach to slider and pinch back closed. Brazing end shut is advised. You can also camouflage a split ring with hollow cord which helps with jingle.
Carefully pry open back of zipper slider and hope it doesn't break. Then slide in ring and pinch slider closed without crimping the working part of slider. This technique is not advised unless you are prepared to replace the slider or entire pack should you goof up.
Mini Cable Lock - you can use a mini cable lock as a zipper pull. This lock can of course be used to secure the zipper slider its attached to another slider, "D" ring at end of zipper and/or even another bag.
Mini Quick Link
Sewlock zipper end prevents separation of zipper once locked
Even with padlock designed sliders, nimble fingers can easily separate the zipper unless the sides of the zipper are firm and prevent flexing of the unzipped zipper between double sliders. Semi hard luggage with plastic reinforced sides are difficult to tamper in this manner, but access into soft backpacks can often be done by just pulling on the fabric adjacent to the zipper sliders. Firm plastic or metal may be sewn or riveted to the sides of zippers to help prevent zipper separation when sliders are locked. Locking the sliders to a D ring sewn to the end of the zipper makes it a little more difficult to separate the zippers than if the sliders were fix or floating in the middle of the zipper. Again, the tighter the sliders are locked together, the more difficult it is to separate the zipper.
Zippers, especially the coil type, can be separated with a little bending or/and picking in a manner of seconds and rezipped with locked but free-floating sliders. Locking your sliders to a fixed position (such as to a D ring at the end of the zipper) will not prevent someone from prying open a zipper, but will make if very difficult for them to cover their tracks and hopefully deter them from doing so. Plastic and metal tooth zippers are more difficult to pry open than coil zippers, but a sharp blade can usually still open up most any bag without much resistance.
Eagle Creek Rincon zipper lock
Adding and anchor point for your zipper lock makes it very difficult to reclose a zipper which has been opened with a pen. It can also protects a zipper to some degree as a hard yank to a lock will be partially absorbed by the anchor point and not just the zipper and zipper slider. This is helpful against yank attacks and damage to zippers when locks get caught on other luggage or the many hazards encounters at the airport.
More information on security can be found on our Backpack Security page.
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