Some awesome riding to be had from Malcesine itself. You can take the cable car up, but you need to book (early on the same day usually works) as there’s only a few rides that take bikes.
There’s various options at the top, and then there’s a great path that drops you down into Navenne – if you can find it. This was my favourite loop, after a few days exploring last time I was there:
http://www.bikehike.co.uk/mapview.php?lnk=http://www.ex-parrot.com/~pdw/cycle-routes/gpx//20110818-baldo-navenne-mk2.gpx
Alternatively, there’s various routes that’ll drop you down into Torbole, but you’ve then got to get back from there, and I avoid the lake side road at all costs: busy, Italian drivers, and lots of tunnels. South of Navenne there’s a cycle path.