Are Roof Boxes Secure?

They stop the box opening at speed, which is genuinely their most important job and one they do well. Most box locking systems will not release the key until every latch is engaged, which is a real safety feature.

They stop casual curiosity. Someone walking past a loaded box in a car park cannot simply lift the lid and look.

They do not stop anyone determined. The shell is plastic and a box is at head height in an open car park. That is the honest position.

• Rest stops and fuel stations: fine. The box is visible, you are minutes away, and the contents are luggage.
• A day at a trailhead: acceptable for gear, not for anything you would mind losing. Park where the car is visible.
• Overnight at a hotel: empty it. Ten minutes of carrying bags is cheaper than anything else.
• Street parking overnight: empty it, and consider taking the box off if you are staying several days.

The rule that works: nothing goes in a roof box that you would not leave on the back seat in plain view.

A cargo box is an expensive item mounted on the outside of a car, and a loaded roof advertises that a vehicle is going somewhere with everything its owners need.

Two things help. Lock the box to the bars — most mounting systems have a lock for exactly this, and plenty of owners never use it. And lock the bars to the vehicle, which most foot packs also support.

Both of those are usually included and both are commonly left un-engaged.

If you have bars, a box and a bike carrier, you can end up with three or four different keys, which is how locks end up unused.

Both major brands sell matched lock cores that let every lock on the car share one key. It costs a little and it is the difference between locks you engage and locks you mean to engage. If you are buying into one brand’s ecosystem anyway, it is the accessory most worth adding.