There's a new bike shop in the closest town to where I live. I've gone in several times with various issues on my bikes and the owner always does this stuff for me for free. Finally, last time I went in I had to insist that he start charging me at least something in order for him to stay in business! By way of "tipping" I guess I am now just buying lubricant and other stuff at his shop. I don't quite know yet how he feels about beer!