Ffs no, nobody should attack before the 3km mark as a precaution for the super steep section. That's a ridiculously stupid idea and I cannot believe how many people have suggested it. You don't plan to ride your own pace without a slipstream in the only part of the climb where a slipstream matters just so you can ride your own pace on a 3km stretch where everyone will ride his own pace anyway. Like, what do you people expect that last 3km will look like? Bernal, fresh as a daisy, sprinting up there like it's the Mur de Huy and Remco being just as strong but not able to follow because he couldn't match Bernal's 3 km long acceleration? Explosiveness will be an absolute nonfactor today. Those kind of gradients for such a long time will always be a grind of sustaining a consistent, high pace, especially after like 10km at 8% after which everyone will already be tired already. Like it or not, today is a waiting game, and anyone showing his cards too early will pay dearly.