Did you consider that is the case because Challenge tires suck?
I saw some Strada Bianchis at a swap. They felt like a garden hose. Just because it is big, it doesn't mean it's good.
There are different versions of that tire. The Strada Bianca COMP is a rather cheap and stiff wired-on tire, the PRO is the much more expensive folding variant. I have the latter on several bikes, and really like how they ride. The only thing I don't like about them are the loud graphics on the sidewall.
