A cyclist friend of mine did a couple run v bike tests with a friend of his and found the tipping point to favor a similarly fit runner on a climb is quite high. Maybe 20% grade or more. I have seen fit trail runners pass recreational mountain bikers on uphill trails many times. Have fun.
Btw, my legs often feel ok the day after a hard ride (such as your 100 miler), then are sore the 2nd day afterwards. It is called delayed onset muscle soreness and it is pretty common. I also don't find that the time of day of rides impacts my recovery. It seems like my recovery is more about nights of sleep since a hard ride instead of hours since the ride.