Thousands of people will be transporting two wheels on four this summer, as they load up their bikes for holidays and weekend breaks. But which are the best, and safest, cycle racks for the job?

We've tested roof and boot carriers here, and both have their pros and cons. Which you need will be governed by the number of bikes, people and kit you want to carry, as well as your budget.

The roof-mounted, single cycle versions are cheaper and easier to fit, plus take up little storage space. However, you'll need one per bike, which can bump up the cost. Also, you have to lift the cycles to head height and, if your roofbars already have luggage on them, space becomes an issue. You will also have to pay for some lateral supports.

Hatch or boot-mounted carriers hold two or three bikes and are easier to strap cycles to. Although simpler to load, packing the rest of the car is tricky as most mean the hatch or boot can't open while they're in place. Rear vision is also affected and some racks will block the number plate and lights, so you will have to buy a trailer board.

Be aware that bikes will get dirty when transported in poor weather, and some racks can be a pain to fit with a tangle of fasteners. Cycles are targets for theft, so for short stops always secure them to the carrier or car with the rack's built-in lock or a steel cable. For long stays, remove the bikes. Finally, check the system fits your motor as even 'universal' carriers have exceptions.

There's no point in taking your bikes out if you spend more time fitting the rack than cycling, so ease of use was key for us - both installing the device and the machines.

We tested 2 , the and the Atera Giro.

We also looked for simple assembly (where needed), security and protection for the car's paint. Storage was also a factor, and while price was considered, it played a relatively small role in the overall rating as we felt user-friendliness and safety were more important.

It was a close-run thing in the roof-mounted section, and we'd be happy with any of the top racks. But the new ratchet system on Thule's 591 gave it the edge over the Atera Giro and Barracuda.

The ProRide clearly had the Barracuda and Atera Giro in its sights, with its impressive one-piece, aluminium design and competitive price. With no assembly, we simply slid the wheel locators into place and threaded through the straps. The arm had a superb rat-chet action, and the carrier comes with two locks, the Thule 591 would have to be our first choice roof mounted cycle carrier.