Thank you all for your timely and helpful replies. I will cancel hiring the local motorcycle washers and if he can't do it by hand, bag it until I find a bike pro in Hanoi. I stay in hotels and have no bike washing facilities. I am disappointed to hear that bicycles are hardly indestructible against the elements! I knew there was a risk and so whenever possible rode on cement embankment further up slope. However, I also figured ' hey, I'm not going to treat my bicycle like a debutante, shielded from harsh realities of the real world in developing countries. Automobiles, motorcycles, trucks, buses, tanks move through the ocassional rain or flood or seawater. I can't be treating this vehicle like it's made of silk and gold.

But now I hear strange sounds...