They are all good (but like Adrian said riding is the correct spelling )

However they are NOT gerunds . Your sentences are all using the present continuous tense!

I gerund or verbal noun is a NOUN in the form of the continous tense of the verb used to describe the act of doing something:

I like (the act of ) reading .

After reading the newspaper I went for a walk.

Walking is good excercise.

Is it right to use the gerund in these sentences?

We listened to the old man TELLING his story from beginning to end.
Listen! Can you hear a baby CRYING?
I look out of the window and saw Dan RIDING his bike along the road.
I thought I heard somebody SAYING "Hi" , so I looked round.
We watched two men CRAWLING across the garden and CLIMBING through an open window into the house.
Everybody heard the bomb EXPLODE. It was a tremendous noise.
Oh! I can feel something RUNNING up my leg! It must be an insect.
I heard somebody SLAMMING the door in the middle of the night. It woke me up.
When we got home, we found a cat SLEEPING on the kitchen table.

Only one gerund is incorrect because a bomb exploding is instantaneous if the bombs were plural then it would be fine, the only other mistake is a spelling mistake!

Hope this helps

Bob

Is it right to use the gerund in these sentences?

We listened to the old man TELLING his story from beginning to end.
Listen! Can you hear a baby CRYING?
I look out of the window and saw Dan riding his bike along the road.
I thought I heard somebody SAYING "Hi" , so I looked round.
We watch two men CRAWLING across the garden and CLIMBING through an open window into the house.
Everybody heard the bomb EXPLODING. It was a tremendous noise.
Oh! I can feel something RUNNING up my leg! It must be an insect.
I heard somebody SLAMMING the door in the middle of the night. It woke me up.
When we got home, we found a cat SLEEPING on the kitchen table.