Is the inquirer entitled to demand from the homeowners the value of his bicycle that was stolen from their house, given his prior knowledge of their susceptibility to theft, and given that they did not inform him of this until after the theft occurred?

If someone leaves their car or motorcycle outside a house they are visiting and it gets stolen, the homeowners are not liable for compensation. This is because there is nothing that obliges them to guarantee its safety. Liability for compensation falls upon the direct perpetrator of damage, or the one who caused it, or the one who had possession of the item. As for someone who did not have possession of the item and did not cause the theft, there is no liability on them. At most, the homeowners might be deemed negligent for not warning you about the prevalence of thefts, but this does not obligate them to provide compensation.