So, my friend Gabrielle asked on Facebook:
Seriously, this is such an oddity of English, one that must have come up before and certainly have been researched and answered by someone of authority, right?
Well, the best I could find searching the web was this entry in the old Language Log blog at UPenn which describes the phenomenon but doesn’t quite explain it. Not being satisfied by this dead-end, I decided to try and come up with a plausible explanation, myself.
What I came up with was this: “In my opinion, if you can ride while standing on a vehicle, you ride on the vehicle. If you must ride sitting, you sit in the vehicle.” This seems to hold for most of the examples cited in the Language Log entry linked above, except for bikes, which you certainly ride on, but ride while seated.
I guess I’ll have to admit that I’m a closeted wanna-be linguist, because I find languages so interesting. I’d venture to guess that most above-average intelligence native English speakers can naturally choose the correct preposition, either “in” or “on”, when referring to modes of transportation, but how do we do that? It seems natural and innate but there’s no way to codify a rule that describes its correctness? How can that be?
What do you think? Can you see a rule or set of rules that correctly describes the proper preposition in all these situations? Do you have insight into how we can naturally determine which preposition to use, but fail to express concise rules for such selection? Do you even care about this at all?
Let me know in the comments below.
Programmer, husband, father, singer, guitarist, tinkerer, reverse engineer, strange, and living in New Jersey. 
What about air travel?
I would say the distinction is mass transit.
But you ride on a bike …
i would say that’s the perfect rule, but altered to say “if it is possibe to stand strait”. It works for planes and boats and conversly for min-vans where you can stand but not really stand fully erect. I assume that pilots of small aircraft or one man planes do say in. though i cannot comfirm it.
We came to the same solution of if you are able to stand then you are ON your given transportation.
“I’m on the boat”, “Im on the bus”, “I’m on the train”. “I’m on my bike”
(you are able to stand on the pedals of a bike, and quite literally unable to get into a bike!)
So what about elevators?
“I’m on the elevator” sounds wrong. yet you are able to stand.
A friend pointed out the Paternoster (http://en.wikipedia.org/wiki/Paternoster) which sounds wrong if you say “I’m in the Paternoster”. I am defiantly “On the Paternoster”.
So whats the difference between an elevator and a paternoster?
When you get on a Paternoster you get on a moving platform for which you have no control over. So for my final codification I have come up with the following:
not_in_control or able_to_stand ? “on” : “in”;
If anyone finds something that this doesnt work for let me know!
Interesting. However, what about riding in a hearse? You’re not in control, but you still ride “in” not “on” …
A bus or a train has a set route and will go there regardless of wether you are on it or not. Whereas in a car you, although you may not be driving, exert a little more control over your destination. If something has a defined route from A to B you ‘get on’.
Just my thoughts, what do you think?
Bicycles and motorcycles have no set route, yet you “get on” them.
An elevator has a set route, yet you get in an elevator, not on an elevator.
I think there’s a combination of rules for this one. But just to quote my English teacher on this: you get on a train or bus, because these modes of transportation are elevated (bus =”stairs” & train = platform). On the contrary, you use “in” for cars because you simply get in a car without it being on a higher position than you are.
What about “I learned to ride (on) a bike when I was five”?
The preposition isn’t needed, right?
Good point. I think… when using the infinitive form of the verb (e.g., “to ride”) instead of conjugated form (e.g., “ride”, “rode”, “ridden”) the preposition should be omitted. However, this doesn’t seem to work universally, for example:
“I wanted to drive the car […]” vs. “I drove the car […]” — neither use a preposition. Hmm.
Such a tricky language … ;-)
Isn’t it?! :-)
Your last two examples imply more control. If you drive in the car, you *might* not be behind the wheel(?). But that’s only musing, really.
“I want to ride to Bristol on my bike”
“I want to ride my bike to Bristol”
Oh dear. ;-)
I think the secret would be in the preposition “on” being optional. You need the preposition to ride in a taxi or on a plane but you can ride a bike without the preposition “on”.