Race tactics, bike handling and the required mental strength for energy conservation and paying attention over 3 weeks are also somewhat question marks. I mean, he could be so strong, that unnecessarily exhausting himself and other errors of tactics or in-race nutrition etc don't matter, but if things are close, it could break his race.
I think having completed a GT even just once gives a significant edge comparatively.
I think having completed a GT even just once gives a significant edge comparatively.