Although it wasn't true, Mike told everyone that he had lent his bike to the boy who lived next door.Here are the grammatical functions of the main clause and the three dependent clauses:
Although it wasn't true, (adverbial clause modifying entire sentence)* Thomas S. Kane, The Oxford Guide to Writing p. 218 (1983).
Mike told everyone (the main clause)
that he had lent his bike (noun clause, direct object of told)
to the boy who lived next door. (adjectival clause modifying boy)
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