With respect to the discussion about the difficulty of the climbs.
I've ridden the Stelvio from every 3 sides, I've ridden the northern approach of Gavia, the Val Martello, Timmelsjoch (Rombo) and Rettenbachferner. I've ridden lots of other climbs but just to stay in this region.
Stelvio (especially as they only go until 2500m) from Mustair is definitely the easiest side. Why? As soon as they reach Mustair it's actually quite steady. You find your rhythm easily. Very nasty is the slightly uphill section from Prad (Prato) to Mustair. There you very often face headwind. Without a proper team you are going to lose minutes. And this is why I think that Dumoulin never has a chance to win this Giro. Quintana will drop him on the ascent of the Stelvio and Dumoulin will never has a chance to claw back time afterwards. His team is just to weak. Without a team you simply die in this section.
What obviously will make the last climb of that stage very demanding are the ascents of Mortirolo and Stelvio beforehand. With a lot of fatigue the Umbrail is a killer. Then, it just doesn't matter that there are no really steep ramps.
The northern ascent from Prato obviously is the hardest approach to the summit. But nevertheless it's not too hard if you ride it alone with no proper climbs beforehand. There are just so many hairpins that you never hit a very steep section. Of course, you need an incredible endurance. But actually, you can find a rhythm. You should not underestimate the southern approach from Bormio. It's a little bit shorter and a little bit flatter. But I did not feel lot of a difference pertaining the difficulty.
All of those climbs are not comparable to Rettenbachferner. That's just a beast. Ride it and you feel it. Stilfser Joch (Stelvio) is nowhere as hard as the giant (highest paved street of the Alps) of the Alps. A stage with Jaufenpass (Passo Giovo), Timmelsjoch (Passo Rombo), a final uphill finish to Rettenbachferner and maybe Penser Joch (Pennes) as the first climb would be a dream. That's a killer and would be one of the hardest stages that we have ever seen in cycling. Time gaps would be insane. The approach with Kühtai (I've ridden it as well) that was ridden some years ago at the Deutschland Tour is hard but nowhere as had as my proposal here.
But gradient alone does not necessarily translate into time gaps. Sometimes very steep climbs produce relatively little time gaps even though everyone arrives on his own. Rather, flatter climbs might produce bigger time gaps, even though small groups arrive together. In this respect Umbrail (Stelvio) may produce bigger gaps by far, just because it's relatively long and comes at the end of a hard stage. Then length is more important than gradients in order to produce time gaps even though the riders feel more miserable at the steeper climbs as Zoncolan.
The hardest climb I've done is not suited for road races unfortunately. 14,9km with an average of 10,8% and heavy gravel. Stelvio is nothing against it. If you need a challenge. Go there. Switzerland is awaiting you.
http://www.salite.ch/9902.asp?Mappa=
Facebook
Twitter
Instagram