It depends on how much room you have at home. When we lived in an 800 sq. ft. condo apartment (mine, from before I ever met him) I did get very frustrated by his packrat habits and eventually insisted he rent a storage facility. He couldn't let anything go - bikes or other things - and it began to seem as though I was being pushed out of my own home and there was no longer room there for me. Perhaps each time a new bike comes in, one should go out? That's the rule that professional organizers impose on people who acquire too many shoes and clothes for their closets.
Failing that, some clever storage solutions might make it seem less as though the whole house is being taken over. In a relationship where one person has collecting tendencies and the other doesn't, it's important to have clear divisions of space and boundaries. The collector most risks the relationship when he/she crosses boundaries and starts to store stuff in the other persons space.