Spot the agreement error in the relative clause: The bicycles that belongs to the rental shop are painted blue.
Belongs should be belong because that refers to bicycles.✓Bonne réponse
That should be whom because bicycles are plural.
Are should be is because shop is singular.
No change is needed because the nearest noun controls both verbs.
Explication
That represents the plural antecedent bicycles, so the relative verb must be the plural form belong. The nearby singular noun shop is inside a prepositional phrase and does not control agreement in either clause.