Thats one of his intentional gimmicks as a tank.
If you can catch him he can easily get destroyed he is weak without his mount.
He is ment to be the Yolo Bull S champion that dashes with the team into the tower and just destroy you.
if you see a kled running at you with 60% to 99% Courage you better hope your team is with you.
He has one of the hardest ults to use since it goes to a set course that cannot be stopped, it hits the first target that comes into view (Most likely a tank but if you do hit it your ment to dash to the back lines with E to get the squishies).
Kled without Skaarl has the worst movespeed in the entire game and if he isn't overfed anyone can 1v1 him but if he is overfed then you better hope you have a yi/xin. I haven't had any problems with lee sin mains ironicly.