Minibikes: Your Ticket to Freedom and the Right to say "Sayonara Suckahs !" to the zombies... whether they run or not.
I've lost my minibike at least 10 times (and recovered it) since 16.x.
I've noticed a few things are usually happening when it goes missing or underground and here are my tips for KEEPING your mount.
Come to a FULL stop before hopping off. I know it's fun to jump off while moving but... you're asking for it.
DON'T park next to any object that can be acted upon. Bike might go underground. See next tip.
If it DID go underground, calm down and LISTEN for it. You can hear this strange chugging sound and when you get to where the sound is loudest, dig CAREFULLY around that sound. If you see the handlebars, you COULD dismantle the bike and then reassemble it above ground. A major PITA, I know. Throw down a chest if need be.
Because the bike sometimes SHOOTS ahead of you (because you didn't come to a full stop and wait 1 second (one-thousand-one..) before dismounting, DON'T park at water's edge facing the lake, stream, etc. Park parallel to the water. These are lessons I've learned the hard way.
Sometimes logging off and back on again makes the bike reappear. Server restart not required.
STAY the HELL away from TRADER territory. If it goes underground there, kiss it goodbye. I park a good healthy distance away and I walk in.
Finally, I had my bike go missing one morning. It went out into the world, apparently, to see the sights and returned a game WEEK? later. One day... it simply appeared in a nearby town - parked on a random street. Go figure.
The bike icon on the compass dial doesn't ALWAYS work and it sometimes will disappear if you wander too far from it. If you're in a woodsy area, maybe put a red temp map marker where your bike was parked? (moot if locks are disabled)
Those are my tips. I hope they spare you the frustration I have had to endure.