What do you use to lock your bikes whilst travelling?
I’m thinking of car parks, ferries, lunch stops, travelling around, staying on campsites etc.

Cable lock round the chassis /tow bar then more to the bikes. And never leave it out of sight.

On the car I used a 3m steel windsurfer cable lock, prior to that I made a steel cable loop with a lump on both ends that went into car via hatch.

On the motorhome – I still use the 3m cable, with a cover over the bikes and that is secured with SPT locking tiedowns

Car parks, lunch stops and travelling around;
I use bike cable locks just around the rack.

Camp sites (UK);
I generally don’t bother with extra security. My perception is that they are safe as most people have a mutual respect for each others stuff when camping.

Whenever I travel with the bikes on the outside of the vehicle I will always take a deep breath and have faith in my insurance. If they are going to go, no amount of cables will stop the determined thief, I always look at it as stopping the opportunist.
I never travel with a bike on the outside of a vehicle that I cannot afford to lose. You can ruin a holiday by worrying too much.

I have an agreement with myself and the missus that if I do lose a bike that way, I already have the next one picked out before we go.

i always keep mine in sight, or a cable lock if they are not.

Having a boot rack negates any sort of security anyway as they can just take the whole thing when ever they want.

if its just me the bike lives in the car, nothing a tarpaulin can’t cover!

nothing as i dont leave them unattended.

If i had to a massive lock locked to the rack [ the rack is locked on in my case]

I think a cable lock and a decent D lock should be okay.

Kryptonite Modulus with loops around the rack, though frames and around second rack. I can lock all four bikes on the roof. If left for longer, just add more locks through rear triangle and rack.

I also use the modulus if I leave a bike inside the car.

towbar mounted- big cable n chain down to car chassis, whenever we park up, i try to reverse into a spot with thorns or bushes- nobody likes diving into thorns- I think it acts as a deterent!

^^^ that and a decent cable lock but in the car for preference

Always have the bikes on the roof rather than on a towbar, and I don’t trust the standard thule locks so I’ve got a 2m pragmasis chain and cen 6 padlock I’ll chuck over the bike if I stop at a service station. If I’m nipping to the shops or something then a decent d-lock and loops for the wheels (and kept in sight)