Giro visit - Zoncolan, Stelvio and what else?

Trento to Ovaro (the town at the base of the Zoncolan) is quite a distance and you'll be hampered by road closures and about 100,000 spectators on the day (possibly more). You'll probably have to go the day before and sleep in the van.

Gavia Mortirolo loop, and Sella Ronda are within striking distance.

If you do get up Stelvio, it is that good, and it's hard because of the length, average gradient and altitude. No really steep bits. And it will be cold.

As Ugo said try the Gavia it is a stunning climb up through the national park and a lot quieter than the Stelvio (when I rode it in mid July a few years back there were only a few cyclists riding it). Some smaller climbs close by like Foscagno, Bormio 2000 and Cancano are also worth a try. Hotel Funivia in Bormio used to have some route maps on their website which might be worth digging out if still available.

Take a look on this site https://www.cyclingcols.com/col/Bondone

A friend is going to the Alps at the start of June and posted a video of the Italians setting deliberate avalanches to start clearing the Stelvio this week; it was on Twitter. It is possible it will be snow-bound when the Giro goes through, it has happened before. I timed my holiday last year to be in the region in the first week of September for Stilsferjoch, when they close the roads to cars and let cyclists have it to themselves. On a good day they get 11000 riders...when I got there the night before it was about 6 degrees and raining, and didn't look good for the following day. Got up early to a covering of snow; the ride kind of went ahead although the road was closed around the half way point. Less than 2000 riders attempted it. It was hard to drive over an ajoining pass, so cycling to the top would not have been possible in summer clothes.

I also went to the Giro in May last year for the Blockhaus stage in central Italy. We rode about half the route a few hours before the Giro went through; the officials got us off the road about 300m from the stage finish so we couldn't do the actual stage finish sadly. We drove up the mountain and left the car about a mile down the mountain from the stage finish on a road the Giro wasn't riding up but the whole circus would use to get back down. When we left the car it was on its own, when we got back to it, it was almost boxed in and there were a couple of tents too! We were staying about 30 km from the stage finish so riding down wasn't an issue. There were notices all along the route about NOT parking anywhere that day, but we took a chance as it wasn't where they would be riding. There were rumours that anything in the area would be towed away, but we weren't going to ride back up the mountain to rescue the car.

If my experience is anything to go by, there will be thousands of cyclists on the day trying to ride as much of the route as possible. Sounds like Zoncolan will be difficult logistically, but I would want to ride it if I was nearby - or at least try!

The most famous climb in Trento is the Bondone, but there are climbs pretty much everywhere either side of the town that might not be famous but are perfectly nice climbs. You could always head down to Levico Terme and do the Rifugio Panarotta climb. It makes a reasonable loop.