One of the disadvantages of car bike racks is that your bicycle is highly visible and vulnerable to potential theft. Leaving the vehicle with mounted bikes unattended even for a short time can understandably leave you with an uneasy feeling.

While I personally never had any issue during all my years traveling with all kinds of expensive bikes, it was surely not because they were hidden well. For a couple of years, the mountain bikes on the roof of my car attracted a lot of attention, as they were worth up to three times as much as the old car underneath.

Even with such a disadvantage, I managed to keep my bikes safe despite attracting unwanted attention – by using simple tactics anyone can apply:

These can be categorized into passive and active, preventative measures to keep travel with car bike racks secure. I’m going into how you can secure any bike on any bike rack from prying eyes and theft. For protection from damage, I got another article on how to protect bikes on a car rack when driving.

Preventative Measures

Let’s Establish our baseline situation: A bicycle (or more) attached overtly to the outside of your vehicle – either on the roof or in the rear of the vehicle.

There is a certain amount of risk for theft or damage to that bicycle. We will later look at specific measures of how to protect against attempts. But before it even gets to an actual theft attempt, we can look at ways to reduce the overall likelihood of your car and bike being the target in the first place. We can do that by deterring potential thieves from even trying in the first place. Achieving that is better than the world’s best lock.

Park in a well-lit area, preferably with CCTV

Image credit: Shane Aldendorff

Before your vehicle even comes to a halt, you can make the first important decision regarding your bike rack safety. When searching for a parking location for a quick stop or for a place to stay overnight, choose a busy location. Busy as in lots of traffic passing by. In this case, foot traffic is the most valuable, as it’s the slowest one able to intervene with any dubious activity.

Busy places tend to be well-lit for those pedestrians. Sometimes there are CCTV cameras placed, some very overtly in order to deter any unlawful behavior. All three of those factors may not be possible for parking lots. Aim for at least two of those three: well-lit, busy, CCTV.

Parking in tight spaces

Sometimes none of the three are an option when parking inside a parking garage (where bikes on roof racks cannot go). Even if you are parking your car and bike overnight or for extended periods of leaving the car, there is a simple and effective tactic to apply when parking near structures.

It’s more than a delaying tactic to reverse the vehicle until it’s almost against a wall, fence, or hedge (even into the latter). My van is oversized for many parking garages, so I constantly use this whenever I don’t dismount my bike. In parking garages that I can enter, I do the exact same by reversing into the parking space. It also protects against people driving into bikes that are sticking out from behind.

Switch up parking patterns

Expensive bikes attract attention. Even more so when they appear repeatedly in a certain place, at a certain time. This applies to any situation where you park your bike, even when it’s on a car. For example, leaving it on after a ride, when arriving home.

Avoid leaving it in the same place on a regular basis. A determined thief might spot your pattern, and target that specific high-value item. The same goes with your parking spot choice. Don’t hesitate to switch it up.

Covers to hide the bike under

Again, this is a passive measure. Fabric and elastic straps are easily moved aside if someone was to walk up to it to get a glimpse of what’s behind. In doing that they are already behaving suspiciously to even get a look under the covers. Before they can even get to make the decision if the bounty is worth the risk.

An awesome benefit of having covers is to protect the bikes from wind, rain, or spray and keep accessories safe. 

Security marking

If you have a proper (police-backed) security marking scheme in your country, it’s worth taking advantage of it. Obvious markings are a further permanent deterrent. It’s one and done. With putting it in an obvious place on the frame, there is a huge disadvantage that you ruin the bike’s visuals. An understandable no-go for many enthusiasts (like me).

Proactive Measures

When using preventative measures effectively, the probability of any of the following techniques being your last line of defense is already drastically reduced. Additionally, bike locks also have a significant deterrence factor to them.

Lock the bike rack to the car

If your bike rack can be removed from your locked car by anyone, none of the following tips are fully able to secure bikes on it. It acts as its own security measure. Especially heavy-duty aluminum bike racks can’t be cut or disassembled easily. And if someone tried, it would attract a lot of unwanted attention due to noise.

Securing the bike rack to the car is the basis to secure anything mounted to it. If the rack itself can be removed by anyone, everything secured to it can be removed with it. Sure, it is awkward to remove and transport a fully loaded bike rack. Explaining the insurance that this could happen because it was not locked is even more so.

Tow hitch receiver lock and steel wire connecting the hitch rack to the car securely.
Tow hitch receiver lock and steel wire connecting the hitch rack to the car securely.
Thule bike rack safety lock strap wrapping around the car rack and into the car under the trunk door or side doors.
Thule’s universal bike rack safety lock strap wraps around the car rack and goes into the car under the trunk door or side doors.

It is extremely rare (especially for modern ones), but some roof- and trunk-mounted bike racks can be dismounted, even if all doors of the car are shut. This is because the mounting bolts are fully accessible and not locked in any way. When using older models or scanning the second-hand market it is still an important aspect to consider. For some models or rack types, there are aftermarket accessories to add locks like simple receiver locks for hitch racks (CURT got you covered) or lock straps like this one from Thule, for trunk racks primarily, but also universally usable with hitch and roof racks.

This obvious flaw is now completely eliminated from new models of the top bike rack brands like Thule, Yakima, 1UP, Saris, Rocky Mounts, or Kuat. So luckily there is no need to weld your rack and car together forever. Instead, roof-mounted and hitch-mounted racks now do come with their own locking mechanisms built-in.

They either directly lock the rack to the car itself (like the hitch) or lock access to the screws needed for removal. In the case of a roof rack, there are locks for every point of contact totaling up to four. Making it the best-secured type of rack.

roof mount 4 edited
Locked roof rack by Yakima.

A secure bike rack is only one (important) part of the equation. There is still valuable cargo to keep safe from prying hands. If there’s any kind of bolt, even a hand-operated screw, you could replace that with something more secure like a lock or at least anti-tamper Torx bolts.

Use common or integrated bike locks

With a secure bike rack, the most obvious and common security measure is to actually lock the bikes to the rack. In most cases, it will not be possible to lock them to the car itself.

This is where locking the rack to the vehicle pays dividends. If your rack comes equipped with its own bike locks, security is incredibly easy. Modern bike racks have so many smart and helpful features. One of them are inconspicuous bike locks tucked away within the actual rack. This way they are always on board and never forgotten.

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Integrated front wheel bike rack lock.
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Integrated rear wheel bike rack lock.

They are not necessarily better or worse than conventional bike locks, just more convenient and on-board at all times. A Common bike lock will work just as well. As my trunk rack came without integrated locks, I always carry my bike lock in the car trunk next to starter cables. In my eyes, there is never a reason to not carry any of those with you at all times.

In my opinion, the diameter of the chain is an important factor. With most integrated bike locks this is an issue. In the case of a thief actually going to town on it, a thin cable lock is about as good of security as a strong rope. Any goon can buy a pair of wire cutters and snap through those relatively quickly.

ABUS Citadel Chain Lock
Size matters in psychological warfare against thieves.

Folding plate locks are is a bit higher security. Primarily they are designed to be carried neatly on a bike making them a valid choice for commuters. Which cannot be said about U-locks, which generally do offer a bit more protection though.

For my own trunk rack security, I personally use a fairly long and definitely burly ABUS Citadel chain lock. It’s long enough to pass through the frame, front wheel, and rack of two bikes. On a single bike, I simply wrap it around two times. That thick chain lock is hardly intended for bike use simply because it is way too heavy to ride around with. Stowed away in my trunk that is no issue. As a huge benefit, the beefy look alone is a major deterring factor for any potential thief even glancing at it.

Without actual power tools, there is no way my bikes are coming off the rack. It gives me comfort to know I can more safely leave my bikes unattended for short periods while on road trips or during after-ride beer stops. 

Lock as close as possible to a sturdy structure

Apart from the actual dimensions, locking mechanisms, and quality of a lock, how you make use of it can increase its effectiveness even more – without additional cost. The trick is to give as little room to maneuver as possible when tieing bikes and rack together. This way it’s increasingly cumbersome to manipulate the lock in order to move it to a more advantageous place in order to damage it. The same goes for the bikes. Often they can be moved quite a bit as is and even more so when loosening the straps around wheels and frames.

By locking all of them tightly together you eliminate having one single point of failure that can be exploited easily.

Lock frame and both wheels

With a limited length of the actual lock, it’s understandable that both wheels are simply not possible or practical. In any case, I would recommend at least locking the front wheel and frame to a sturdy structural part of the rack using one lock. This is because the front wheel is the easiest to remove quickly, especially with those quick-release axles modern bikes are equipped with. A (carbon) front wheel by itself can be valuable booty for a thief. It has resale value because dimensions for front hubs and wheel dimensions are standardized.

mountain bike locked to a trunk bike rack
My mountain bike locked to my trunk bike rack. This is how I travel and park overnight.

In any case, DO NOT loop your lock through only the front wheel. On most bikes, it can be removed very easily.

Use two different locks

This is a method to completely go all in and eliminate any weak point. One lock can be used to tie the front end of the bike together, the second one for the seat (if the lock is slim enough), rear-wheel, and rear triangle. All in an effort to complement the front cable. Giving weight to two different locking mechanisms may not be the move, rather making sure both are of sufficient quality and thickness is.

Make use of the car’s alarm

Your car probably comes with its own alarm system. Why not use it? In order to do so, the car needs to support this proprietary feature. If it does, the way this works is hooking a cable look from the trunk to the outside and around any valuable cargo you might have on there. The same way the car detects break-in attempts by vibrations and movement, it does so using this method.

Another similar approach is to use a separate bike alarm. One of the first ones to do it was the ABUS Bordo folding lock. I had the chance to test it and let me tell you: That thing is stupidly loud (100dB) and audible for a long distance! It does also go off relatively easily by minor movement.

Anyway, bike lock alarms are done with specialized bike locks that come with acoustic alarms or notification apps for your phone. Both detect if your bike is being tampered with. Obviously, the additional alarm features are only useful when you keep the preemptive measures from the top of the article in mind: busy places where the alarm can actually be heard by someone. If you yourself are more than a few minutes away from your bikes app notification is not really helping. Down below I get into how you can GPS track if the worst case happened.

For anyone sleeping in their car, this can be a huge benefit though. Again, the more obvious you can present the alarm, the more you are deterring any potential thief. Potential hiccups: These things need batteries, that need to be checked and replaced accordingly.

Locks shouldn’t reach hard surfaces

The reason is that any treatment with a hammer is only possible when there is a hard surface in reach to hammer on. Hammering a lock is a valid technique to get some locks to unlock – or rather get damaged enough to break. An easy way to ensure this is to tighten everything up by wrapping the lock one extra time thus keeping the movement and sway to the absolute minimum.

So, for hitch racks and trunk racks make sure the lock cannot be moved in such a way that it hangs to the ground or can reach your trunk door. The same goes for roof racks, where the car’s roof is the nearest hard surface. With that being said, the actual rack is more than likely built tough and sturdy. For most bike racks the structures you want to avoid are the actual trays the bikes stand in.

This way it’s never hammer time.

Remove e-bike battery

The battery of an e-bike is arguably the single most valuable part. Removing it instantly makes the entire bike less desirable – if not slow and awkward when riding off on it. The most important part here is that the battery is in fact not visible. It can be nearby inside the car, but it might be just as well be in another country if there is no way to know for sure. The same goes for any key. None of that should be in reach or even visible at all.

Reactive Measures

The following steps are reactive in nature after the worst-case scenario happened. However, some do need to be prepared in advance.

Identify & document your bike

This is as easy as taking a couple of deliberate pictures of you and the bike. Make also sure you know the basic, recognizable characteristics of it. The most important data include make/manufacturer, model, frame number, color, and any particular features. Still, pictures are the most helpful here as they are extremely helpful for identification. This increases the chance that anybody (police, local community) can actually identify it and then return it back to you.

Hidden AirTag Airbell
Hidden bike GPS beacon by Airbell

GPS beacon

One way to not depend on others to find and locate your stolen bike is by doing that yourself. It is possible to do so by attaching your steel with a GPS tag. This allows for locating the beacon in real-time and in any location. And it doesn’t have to break the bank! One very accessible solution for under $30 is a single Apple Airtag (found on amazon).


Don’t forget to report the theft to your insurance company. For this to make any sense you need to have an insurance contract covering the bike – duh! Preferably coverage in any location, which makes sense when owning a bike rack.

Usually, you’ll need an official theft report to show to your insurance provider.

Report Theft

Here’s an easy one: Make it easy for people to return your bike to you. If nobody knows you are missing one, how can anybody help in getting it back?

Sometimes bikes are found after they’ve been stolen, but then the owner turns out to be untraceable. So always report the theft to the police. By specifying the clear characteristics of your ride, there is a greater chance that the police can actually return it to you once it reappears.

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  1. Thanks for a very comprehensive article. I’d love to know the make and model of your bike rack you pictured as it looks like what I am looking for myself. Thanks!

    1. Hi, Carol! You’re very welcome 😉
      That’s a Fiamma Carry Bike trunk rack for the VW T5 van. So it’s very specific and only fits that car model.

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