There are several trails for mountain-biking around Lake Como taking you through some spectacular scenery, through the mountains as well as along the lakeside.
Many of the hotels rent out bicycles but if you are looking to do some serious mountain-biking, then it is probably wise to hire the equipment from a cycle shop where they can provide you with the correct bicycle and equipment.
There are various shops in the northern part of Lake Como where you can hire bikes as well as Bici Sport 2000 in Lenno.
The Cavalcalario Club offers a selection of activities around Bellagio including mountain biking.
For fast bicycle hire have a look at www.rentalbikeitaly.com – Veloce bike. the can organise for your bicycle to be collected at your accommodation, train station or even at the airport.