I have recently bought a roof mounted bike carrier from facebook market place as someone was selling cheap. However it doesnt have any locking system to it. What do people use for this? Is it just a standard padlock or is there a specified lock.

Also what bike racks are you guys using? Interested to see whats popular if I ever want to upgrade or if this one breaks.

I use bike racks as little as possible. Instead, I buy cars with interiors that allow me to keep my bike inside the vehicle is there is any chance I will be leaving my car for more than a minute or two. When your bike is inside the car it is protected from the elements. A few years ago I did a 1500 km trip from Montreal to North Carolina. WE transported 2 road bikes and sufficient luggage for a week inside a 2003 Volkswagen Passat 4 door sedan. We had to make a couple of overnight stops. I would not even think about using a bike rack for a trip like that. On the return trip, we drove for at least 10 hours in driving rain. I have a hitch rack on my current car, I use it when I have ridden my mountain bike on muddy trails

I use Thule Bars and Rockymounts bike holders. I did buy the Thule lock kit so it makes it harder to steal the rack off my car. This way I can leave it on all year round and not have to worry about it. The Rockymounts are not locked to the Thule bars, I could but it takes quite a bit of work to get them on and off so I don't worry. They do have fork mount locks and I use these for short stops. When the stops are longer I bring along a Kryptonite, more for show than anything else.

I have no problem with driving any distance with a bike on top, they aren't works of art, they're bikes, they can handle it. I don't want any bike inside my car unless its my Brompton and it stays in the back. My car is in pristine condition including the interior and I plan to keep it that way.

I put in the bed of my truck. If I must leave it unattended I run a cable lock through the wheels and frame and lock it to one of the tie down rings.
Jon

My Yakima rack has locks but when I've been particularly paranoid, I just ran a cable lock through the roof rails.

Letting people know the brand would be helpful. Thule, for example, makes locks to deter theft of the rack itself (I can testify from personal experience that someone can still pry the rack system off the roof) as well as locks to prevent the theft of bike from the carriers.

I don't leave my bike outside on a car rack unless I can see it, and even when I can see it I usually use a thin cable just to keep someone from casually walking off with.

I don't see any roof racks with enough security to leave my bike outside in plain view with me gone for a while.

My dad (I'm in my 30's lol) has an SUV with tinted windows, he leaves bikes inside the car while eating and he can't see the bikes and it hasn't been a problem. But that doesn't advertise that there are bikes in the car.