Panniers are a nice alternative to backpacks when you want to store your gear outside of your panniers. Unfortunately, they are also easy to steal when locked with a regular lock. The best solution is using hard-to-cut straps or chains attached directly to the bike.
This article will show how to use steel cables instead, which offer similar protection against thieves' tools and manual cutting while being much cheaper than strap locks and making it easier to remove the bags for airline travel or just for locking them down in parts of town where theft is more common.
We like to put our cables under the top tube because that's where they're well protected from thieves standing in front of your bike. Our usual setup is using one cable to pull out both panniers together, making it harder for the thief to get access to either bag without damaging them or his tools.
You can also use two separate cables for each bag if you prefer, but keep in mind that this will allow thieves more opportunities to break your locks without damaging your bags.
The carabiners are attached so they always stay at the bottom when you lift up the bags. This makes locking and unlocking easier while preventing scratching paint on your frame. If you're annoyed by rattling noises while riding then securing one end of each cable with a string or rubber band will silence it.
If you're only locking the bags to themselves then you can connect them by looping one end of each cable through the other. If you're using two separate cables for each pannier, then attach them together with zip ties before looping them around your frame.
What if you leave your bike unattended?
Panniers that are locked to the bike with separate locks like this are easy targets for thieves that can't find an opportunity to steal your bike itself. If you plan on leaving your bike unattended for extended periods of time then it's best to either remove the panniers or use a different lock.
Some people use cable locks as secondary deterrents but we like using them only when there is no safe place for us to leave our bikes (e.g., indoor train stations). Carrying cable locks also adds weight and bulk, so think carefully about whether they will be worth their additional cost in terms of hassle before getting one instead of a standard D-lock.
- Use a handlebar bag
If you need quick, easy access to small items that can't be safely stored inside a pannier you can use a handlebar bag instead of a set of panniers. Most handlebar bags attach securely to the bike using a wire or plastic bracket that can't be cut by hand tools, and many have simple zippered pockets for storing valuables.
- Inner bag or frame bag
Many handlebar bags are themselves locked to the bike with a zip-tie. Alternatively, you can get a larger and tougher inner bag or use a simple nylon strap around your seat post and saddle.
- Smaller items of clothing in cages between your wheels
Stuffing unimportant pieces of laundry into smaller plastic bags secured between the wheels of your bike is another common idea that we find too inconvenient to be an effective deterrent against determined thieves.
This approach is also more suitable for road bikes than mountain bikes because it's harder to get access to items located further from the ground on smaller frames, but some people use it successfully on small-wheeled bikes as well. We think there are better ways of organizing our stuff and don't see the need for this in most cases.
- U-lock on seat post or saddle
You can attach a U-lock to your seat post or saddle using one of these small metal hooks:
Your lock must be long enough to secure your frame too, typically around 30cm if you're locking just the wheels and you have quick-release skewers. To keep it from rattling when riding then loop some string or rubber bands around its body before securing them to the hook. This trick also helps prevent damage that could weaken the strength of your lock.
- Take panniers with you when leaving the bike
This is the most effective option in most situations, but it's also the most inconvenient. Removing your panniers and carrying them with you when you leave your bike means that they can't be stolen by anybody who tries to break and run (or ride) with them.
- Put your bike where you can see it or where people will notice it
This is another way to avoid a thief running off with your stuff. You can lock your bike up somewhere else and then sit near it or stand in the area so that you can see people going past, even if they turn their heads away from you. Thieves generally dislike being watched while they work so this is one of the most effective techniques for preventing snatch-and-grabs or quick thefts from racks.
- Make panniers unremovable
As a last resort, some people cut holes in the bottom of their panniers and then install plastic or metal bars inside the bags that go through these holes. This prevents thieves from cutting open your bags with hand tools because they will damage them when doing so (which is time-consuming and difficult). The bars also make it impossible to fit your pannier rack inside any other bag.
- Locking panniers with a steel cable
You will need a pair of panniers with loops for padlocks. Avoid zipper pulls and hard plastic hinges as they can damage the cables. Also, you will need two carabiners - two lengths of steel cable long enough to go all the way around your bike frame, or one length for each end if you're only locking the bags to themselves.
Carabiners are much cheaper than dedicated locks, but they're also easier to cut through so don't use them without additional protection. If your panniers have D-rings sewn into their fronts that provide some additional protection against cutting, then you can attach your zip ties to the rings instead of the loops provided by manufacturers.
However, the cables can be easily cut by bolt cutters so this might not be an ideal solution if you're traveling through high crime areas where even hand tools might be used by robbers.
Some people advocate using two locks of different types to prevent thieves from getting access to both ends of the cable, but we think that your average thief will have no problem using some kind of tool to open one end of the cable.
Locking panniers is a useful way of defending against bike thieves and we've seen many cyclists using this method successfully. However, we think that most riders can benefit more from taking other measures such as selecting good locks and locking their bikes appropriately. There is no point in locking your bags if your frame isn't secured with a quality lock at all times (whenever you leave it unattended).