Hello Pathos,
I think the best way is to use a "Group" field in your two content types "bikerides" and "Walk".
This Group field must use a content type "Location".
This content type "Location" must have all fields (address, zipcode,...,lat,lng,...) which are not exclusively for this content type. When you create these fields, set the padlock open. It will store all those fields in the #__cck_store_item_content and they will be available for all content type.
So like that, in your search type (search form), in the CCK field you put as live value the name of your two content type "bikerides,walk" and the match must be "Any word exact".
It will search in the two content type, and like "Location fields" will be in the two content type, you can display all your result on one map.
Hope it will help.
Lionel