I don't, but if you don't find them on AC and end up buying in the city people are going to tell you to go to Hop Sing and it's true, they have the biggest and most well equipped bike shop. But I have had 2 terrible experiences with them which left me leaving the shop after a lot of wasted time.
But if you keep walking several blocks down the street that Hop Sing is on (go far enough to cross the canal), you will come to Quan's bike shop. Not as packed and impressive but they have beach cruisers and all the doo dads and they are *very* helpful. Prices are comparable. Even if you go to Hop Sing first, if you get annoyed and feel the need to leave, don't hesitate because you think you'll be going home without a bike. Just go down the street.
PS the water taxis should let you bring 1 bike per person for free. Make sure you ask at the store to have them boxed up so they don't get scratched and banged up.