Surely there'll be a fragment of fabric caught in the chain stay with a blood stain identifying the owner by DNA....
My money's on the Marketing Director who, leaving the bike at work [carefully wiped down for prints as he once got collared for jaywalking on Oxford Road while out drinking with student mates in Manchester in 1982], took a train to Blackpool, leaving his clothes neatly folded on the beach just above the high tide line... he's started a new life free of the worries of the commercial pressures of digital burn-out. His only lasting regret is leaving that bike- he always meant to retrieve his bike and get the rear mudguard fixed but it would've left a credit card trail back to Warrington, where he's a night mortuary porter at the Warringtion and Halton Hospital.