i haven't yet after probably at least a hundred hours and a couple dozen shops. i would not patronize such a shop unless it was too cramped for carts, given that the bike is narrower, shorter, and more maneuverable than a cart, and that it speeds/obviates bagging waste. one time i was informed repeatedly that i could leave the bike up front. i repeatedly stated that i was willing to leave the bike up front if they required, but that i preferred to keep it with me, and they seemed to accept that sincerely. another time i entered on a rainy day, and i was asked to be mindful of the (minimal) water dripping from the bike and what a slip hazard that could create for other customers. i found that a very reasonable point, politely made, so i cheerfully left the bike folded at the register.