Freccia trains… safe to lock bags on racks and wander the train a bit

I’m sure you will need to use the bathroom at some point too. If you are traveling alone and nobody can watch it for you, locking your bag is not a bad idea. Take your ticket with you in case you are asked to show it during your wandering. When I was young in Italy, traveling by train with my friends, we were constantly wandering the trains from end to end trying to pick up cute girls visiting Italy. Sometimes we even forgot where our seats (and bags) were.

I would say that in a whole life riding Italian trains, I still have to see with my own eyes a bag locked to the rack, and I still have to witness a case of a bag being stolen. At least, be sure you do not block other people retrieving their bags.

As for wandering, the old car layout with compartments and a separate side corridor somehow encouraged getting up and strolling a bit, but the present, airplane-like layout does not make for wandering. You can always go to the toilet, or look for the restaurant car (vending machines on some trains like Italo), but the idea of wandering car to car, just to spend time, defies my mind.

The probability of your bag going AWOL on a train is similar to it disappearing in the bowels of an airport. If you do not worry about the latter you should also not worry about the former.

I leave my suitcase in the luggage rack at the end of the train without much thought. But I do not keep anything that is not readily replaced in there. My valuables I keep in my day pack. And that usually stays with me, but I will even leave it at my seat to go to the toilet. But I will not leave it unattended while the train is stopped in a station.

What you need to know is a bit of psychology...
Criminals want to just grab and disappear. They do not hang around afterwards, so your stuff is pretty safe while the train is moving.
They do not like to draw attention, and when confronted will just drop the loot and run away. Which is why it is during stops at stations that you need to be vigilant.

I've seen them used on OBB trains and Hungarian trains, but not a lot. I have read that some trains in Portugal have cable ties and that the new RailJet trains have cable ties, and from: Le Figaro newspaper, apparently a thing in France.

“On French trains, passengers must be extra careful and find ways around them. Increasingly, they are locking their luggage with a padlock. This trick is authorized by the SNCF, as long as personal belongings are stored in the designated spaces (above the seats, between back-to-back seats, and at the ends of the carriages) and as long as this does not prevent other passengers from storing theirs.”

There are some nice lightweight locking cables on Amazon for this. Personally, if I did anything, it would be to tie mine and my companion's case together. No one would grab and run two ... I think. But do what puts your mind at ease so you can enjoy the holiday.

I’m not sure there’s a huge overlap between Le Figaro readership and train ridership in 2025. In 50 years taking SNCF trains regularly, I’ve never seen a lock.

I do use locks on my suitcases when travelling on European trains, especially in Italy. But, I usually thread the lock (a Pacsafe extendable steel chain) through the suitcases, so anyone trying to pinch the cases would have to try and drag two or three suitcases out at once and through the narrow train doors. I don’t put suitcases in the overhead racks, but on the racks either end of the train carriage. Smaller bags stay with me under the seat.

But, I usually thread the lock (a Pacsafe extendable steel chain) through the suitcases, so anyone trying to pinch the cases would have to try and drag two or three suitcases out at once and through the narrow train doors.

I have done the same, cable locking together multiple bags, and also looping the cable around a rail on the rack. This was 20+ years ago, when I was still traveling via trains a lot, traveling with my family, multiple bags and cases. My train usage today is fairly limited, mostly Eurostar between Paris and London, with few stops, easy to watch my bags at the end of the car for whatever stops there are.