Here's a way to remember traveling prepositions:
1. If you can stand or walk on it, we use the preposition "on" (e.g., a train, plane, ship, subway)
2. If you have to sit in it, we use "in" (e.g., a car, a truck, a rowboat)
3. If you actually sit or stand on top of it, we use "on" (e.g., a motorcycle, a bicycle, a skateboard)
4. We use "by" to indicate the method of transport (by car, by plane, by sea, by air, by bike, etc.).