I am doing the heroic on a 30t or 32t Suntour freewheel and can't even imagine doing it on a 24t. I have used a 28t on it and one climb in my area is 2.5 miles with 6% average (1st mile is 10%) and it hurts . . . a lot. My concern is my tire choice of Challenge Paris-Roubaix and them holding traction on the gravel..