Sorry if this has been done before, if so I can’t find it.

I’m thinking of getting a towbar mounted bike rack. That locks to the towbar. All well and good.

What options are there for locking bikes to the rack? Big U lock and chain/cable through the wheels would seem to be a good start. But with so many nickable bits, anyone with a set of allen keys could make off with your suspension, dropper post, etc…

Does anyone make a sort of lockable, wire reinforced cover?

(Also do those covers that go over the bikes truly protect them from road ming?)

On the motorhome we use a Taylormade 2 bike cover (seems a bit better material than Fiammia), it’s black and non see through – in terms of road ming – I say yes (*motorhome halfway up back carrier,I put cover over bikes and also wrap it up under bikes with strong spring clamps.
https://www.taylormade-covers.co.uk/acatalog/Bike-Cover-1.html

Under the cover,around bikes, is a 4m thin steel windsurfer lock cable[see ebay] (does frames, wheels and saddles[if I can be bothered]).
over the bikes and cover I use a locking windsurf clamp straps (see http://kanulock.com/ – they’re wire reinforced) it sort of clamps the cover to the bikes[to stop it wobbling) and is thru bike carrier and is wrapped tightly around bikes.

Hadn’t thought of lockable straps – not a bad idea – still presumably are easily cut with wire cutters! I guess if you’re really worried about security the bikes have to go inside.

I’ve got a Pragmasis chain with the ‘noose’ end. I measured the routing using a hosepipe and got the chain so it’s long enough for the the noose end to go over the crash bar behind the rear bumper. The rest of chain then loops through the noose, comes out from under the bumper, goes through the middle of the frames of the bikes and is locked with one link through another around the down tube of the outermost bike.

You’d need to either cut the frame and cables of the bike, cut the chain, or dismantle the back of the car to get a bike off. Obviously parts could still be taken but it’s just for short term security when at service stations and the like, I wouldn’t leave it like that overnight.

(Also do those covers that go over the bikes truly protect them from road ming?)

I’ve never considered it a problem that needs solving tbh.

Your chain system sounds sensible.

I’ve never considered it a problem that needs solving tbh.

You like covering your bikes in salt on road trips when there’s no opportunity to wash them? Each to their own…