Preposiciones de medio

Genéralmente la preposición para un medio es by, teniendo presente que existen numerosísimas excepciones.

by car / taxi
pero: in my/a sports car, in George's car, in a taxi

by bus / coach / underground
pero: on the bus, on an air-conditioned coach

by train / rail 
pero: on the train

by plane / air / jet
pero: on a plane / jet

by boat / ship / ferry 
pero: on a big ship, in a boat

by bicycle / moped / motorcycle
pero: on his bicycle, on a new moped / ...

 Ir a / en...

      to walk                                  --------------->     to go on foot

      to drive                                  --------------->     to go / travel by car

      to ride a bicycle / to cycle       ---------------->    to go by bicycle

      to fly                                     ---------------->    to go / travel by air

      to ride a moped / motorcycle   ---------------->    to go / travel by moped / motorcycle