If someone does right by you take care of them. I take care of my usual UPS guy because he leaves cases of wine at my house without me signing (totally against UPS policy, but he told me that and we have an agreement) so I take care of him at the end of the year (he's risking his job for me - kind of worth something?). It makes my life less complicated and saves my wine another hot day in the brown truck. If your bike shop goes out of their way to treat you right return the favor. You know "Return the favor - Give a little back" (Great line in the movie "I Love You Man"). But if they aren't doing you a favor why should you give them a gift in return? "Here you go have some more money for doing the job you already are getting paid for." Please.....
I want to spit every time I see a tip jar in a place it doesn't belong. F Starbucks, F Dunkin Donuts, F most places nowadays......