Most of the ones I frequent do, but my favorite/closest one... well, I've never had occasion to ask, but I don't think it does, because its a small little shack that barely has AC. It looks like someone subdivided a warehouse/loading dock and made several rentable units. There may be a toilet tucked in some back corner (legally there probably has to be), but its probably one of those tiny, airplane-sized ones... I guess it all depends on the shop. I know some stores in town have dedicated changing rooms, but this LBS doesn't sell clothes, its mostly a commuter/service shop.