Some of this is not a training problem, and treating it like one wastes time your dog may not have. If they are distressed when you leave, if they growl or guard their food, their toys or you, if they are frightened on the lead, or if anything about them changes suddenly at any age, contact your vet the same day. A tip from a website, ours included, is not the answer. If it cannot wait, contact your nearest emergency vet now.
With a Dalmatian, watch their toilet habits and their ears. A Dalmatian who asks to go out again and again, strains, or has accidents in the flat may have a stone, not a training problem, and that cannot wait. A dog who seems to ignore you, snaps when woken, or comes back slowly from the park may not be hearing you. In an older Dalmatian, new pacing or staring at night, when they never used to, can be the start of cognitive decline. Bloat (GDV, a twisted stomach) is most common in large, deep-chested dogs, so skip walks and hard play shortly before and after meals. A swollen, tight belly, retching with nothing coming up, sudden restlessness or drooling is an emergency: contact your vet now.
He'll keep asking for the bike ride. If he's straining when he pees, call your vet.