Can I bring my bicycle on the metro?
'Bicicletta' — bi-ci-CLET-ta. Stress the third syllable; double 't' is held briefly.
Ask at the ticket window or information desk before trying to take a bike through the turnstile. Rules vary by city and time of day.
'Posso' is the first-person singular of 'potere' (can/may). 'Portare' means to bring or carry. The preposition 'sul' (su + il) means on the. This modal + infinitive construction is the standard way to ask for permission in Italian.
Le bici sono ammesse?
Are bikes allowed?
More formal phrasing using past participle as adjective.
È vietato portare la bici?
Is it forbidden to bring the bike?
Negative angle — useful if you suspect the answer is no.
Posso portare il monopattino?
Can I bring the scooter?
E-scooters and folding bikes have different rules.
In Milan, full-size bikes are allowed on the metro on weekdays before 7am and after 8pm, and all day on weekends and holidays. In Rome the rules are stricter. Folding bikes (bici pieghevoli) are generally always allowed.