Keeping an eye on luggage while on a TGV (or other) train?

Put your suitcase on bottom of pile,, that helps,, and I try and book seats close enough to see the luggage area.. the tgv and thalys trains I booked for summer don't worry me too much a they are non stops,, I think trains that stop and alot of stations probably have more risk of suitcase rifling or stealing, i mean who wants to be stuck on a train for 5 hours after just going through someones case and having stolen items on you, lol

Some people here use small locks to connect their luggage to the rack. That, along with maybe zip ties around the zippers to discourage rifling through, would be pretty secure. But generally on high speed trains you're at less risk that trains that stop frequently.

I always use a travel lock to prevent someone from easily opening the bag. Many people use a cable lock to secure their bag to the rack. I'm not a big fan of that since it can hamper other people's ability to remove their bag or delay's exiting at stations. But it will give you piece of mind. And as others say, the TGV has few stops so the risk is low anyway. I always pay attention at station stops.

Put the opening and handle toward the back of the rack. Get there early so it's on the bottom.

Over the years we probably have spent a couple weeks on trains from Italy to England and then some. We have never had a problem but have read a few tales about problems. Take reason precautions and apply a little common sense. Some observations - The slow, regional trains probably have the greatest risk because of the frequent on and off. Also when the train is originating in a station and it is open for boarding for a long period of time. This is when the "solicitors" can come through and you should be very suspicious of anyone coming through in this manner. Second, a lot of train users just toss their luggage in the end bins. Assume most of them are locals so if theft is as huge a problem as we discuss here, the locals would not do that. We do lock our luggage together with a cable lock and secure it to something if possible. Fail to see how this would hinder other passengers. When we put the day bag on the overhead rack will always wrap one of the straps around a rib of the rack just to prevent a quick snatch and dash. And finally, all of our luggage, day bags, etc. are secure with small combo locks. The risk is low and some precautions will make it even lower.