Is it possible to ride the shen in the town. I heard rumours but I don't think it is possible... Can someone help me?

You cant actually "ride" a Gaoren. What you can do, is to
jump into his mouth while hes blasting the bridge,
though I would not recommend it.

There, you can place dragon bombs and carve him.

answering your question, no, i dont think its possible to ride it in the town, only at the fortress, from the bridges

you need to be fast btw, dont lose your time by carving it

thanks for the help guys