Beldum (Japanese: ダンバル Dumbber) is a dual-type Steel/Psychic Pokémon introduced in Generation III. It evolves into Metang starting at level 20, which evolves into Metagross starting at level 45.

How do I evolve Beldum?

Beldum is a Steel, Psychic-type Pokémon from the Hoenn region. It evolves into Metang when fed 25 candies and its final evolution is Metagross.

Why is my Beldum not evolving?

If with "auto leveling loop" you mean that you left Beldum at the Daycare and you are riding the bike in loop in order to make it earn easy experience, then you'll need to raise another level by battling or give him a Rare Candy to trigger the evolution process.