"O yanlış otobüse biniyor."
Translation:He is riding the wrong bus.
Either is fine. (I think I'm more likely to say "taking the bus" when I'm talking about getting on the bus, or the general act of traveling by bus, and "riding the bus" when I'm talking about someone who's sitting on the bus at this moment...... but I don't think that distinction is universal. =) )
Maybe riding a bus is American as in Uk I have heard takıng a train ride taking a bus ride maybe but riding is usually horses or a camel so I agree with Veritaju there. He is on the wrong bus maybe??
Well, 'binmek' only means to get onto a bus/train/bike/horse/etc.; 'riding' for me sounds like being on it already, after having got onto it. Which is why 'riding' sounds wrong to me in this context. But maybe there actually is some regional distinction in English concerning the word 'riding' and it might only mean getting onto the respective vehicle in some regions. =)