If It's Tuesday, There Must Be A Riddle

I help people do tricks and have some fun,
But treat me wrong and I come undone.
If you hold me tight then let me run,
I'll hurt your hand, not much fun.

I'm very strong but yet I'm weak
I can stop a horse and jump a creek.
I couldn't push you through a door
Yet could pull you off the floor.

What am I?