The other day I lost my keys. To matter worse, all the keys for the bike locks disappeared along with the other keys! I'm guessing that there was hole in the trunk bag and they ended up lost. Any idea to prevent this again?

Was there a hole in the trunk bag? Keep an eye out on your next commute. You never know.

A while ago I lost a glove that I'd stuck into my jacket pocket. A day later on the way to work I found it on the bike lane in front of a stop light. So you never know.

My strategy is to attach important items with strings and clips. All items in my pockets are sorted out according to functions and put into pouches that clip on the strings and the keys on interconnected chainrings again clipped on the strings. The opposite string ends have hoops that go onto the belt in everyday life. In my travel pants, most pockets have hoops sewed in to which the strings attach with another set of clips. All of this evolved from bad experiences, particularly losing electronic car keys for the price of which you could buy a decent used bike. Various items in my backpack clip to the hoops in the backpack, etc.

I have two sets of keys. My regular set and my bike set. The regular set stay in my street pants pocket, and the pants are in my backpack when I commute.

I ride in golf/coaches shorts with belt loops and front pockets. My bike set of keys is on a key ring with a coiled bungie (like a telephone handset cable) with a clip at the other end. I clip the coiled cable to my belt loop and carry the keys in my front pocket. Been doin this through three sets of shorts now and the keys have never fallen out while riding. BUt once arriving to home or work I have droppedthe keys, only to have them dangle at my side.

Similar here in that I have a building set and a transportation set for bikes and cars. There are spare clips on the key rings so I can add temporary keys and or separate the sets and still be able to attach the set to something more secure than the set itself. My strings are multicolored with colors I usually wear, to let them blend in.

I have lots of bags: messenger bags, backpacks, musettes, etc... Use a different bag most days depending on the ride. For many years I used to keep my keys in my bag but no more since I left the house in a rush and left my keys, wallet, lock in the bag i left at home. I now keep my essential keys - house, work, u-locks - on one ring and put it in one of my front pants pockets (the other front pocket has my mobile phone). I store my keys and bike gloves in my helmet next to the door and they're the last things I put on and in my pocket before I leave the house.

I usually clip my keyring to a belt loop. It's reliable until I'm not wearing pants with belt loops. Then I have to think of something else.

After I lost my keys I rode back and, if they were lying there on my route, I would have found them. However apparently somebody picked them up, possibly to ask around. I called the local police and they were not surprised. People turn in keys to them on a regular basis, but I had no luck. They even encouraged me to call again and to leave a phone No with them so they could call if something turned up. Afterwards, I had a brass plate made with my phone engraved, check Ebay, that I attached to my new keychain.

Whoever finds that, if you should lose it, would then be able to reverse-look-up your phone number and rob your house.

The crime rate is pretty low where I live, with the lack of any significant expected gains compared to trouble behind in part. If you were really bent on breaking in you could just kick in the window - simpler than reverse engineering the phone No. If I am not sure whether I locked the door I do not go back to check - waste of time in practical terms. However conditions vary depending where you are and other circumstances.

Be more careful?

Stuff happens, and lost keys are common enough.

No idea how to prevent it, except more attention to detail, and maybe a coded tag which will help recover them if found.

In any case, it's wise to have a master set of ALL keys kept in a safe place, because making duplicate keys is far cheaper than replacing locks.

Why would you have to guess whether there is a hole in your bag? Just look at it. If so, fix it or get a new bag. Seems like a simple fix.

I clip them to the lanyard in the back pocket of the rack trunk. The last one had a hole worn in it by the keys moving around, but it took several years for that to happen,

Many saddle bags come with a key clip on a short lanyard/tether. You could add a clip attached to a loop of cord, then sew it into the trunk bag. Or put the loop through any internal zipper pull, etc.

Or, the expensive high tech method

Tile uses bluetooth radio to make the fob beep when you are within 100 feet or so. Of course, you need to keep it's battery charged, have the phone app running, etc.

I minimize my use of keys.

I carry my bike lock in the backpack,and I strap the key to the lock (if not out in the open somewhere). So if I have the lock, I also have the key.

It is possible to get combination door locks.

I just use combination locks. Granted, I live in a relatively tame area, and have a cheap bike in case I'm worried about theft.

I also separate my keys. I have a house key, shed key and bike lock key on one key ring. i put it in my Jersey pocket.

Double bag.

Put a key clip in the bag.

Red Oxx Pin Mount Key Clip

my ortlieb bag has a key strap. I really like having a place to hang my keys that travels with me

I carry my keys in a pocket of my trousers or jacket, attached to a chain (or wire) that connects to a ring on my belt or jacket. Been doing that since I wore a hole in my trouser pocket.