I dont know what to do

Hello

I set up a scene and imported bike and that looks like this

Imgur

I made a script for moving a bike

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Kretanje : MonoBehaviour {
public float speed;
private Rigidbody rb;
void Start () {
rb = GetComponent<Rigidbody> ();
}
// Update is called once per frame
void FixedUpdate () {
float MoveVertical = Input.GetAxis ("Vertical");
Vector2 movement = new Vector2 (MoveVertical, 0.0f);
rb.AddForce (movement * speed);
}
}

But my bike is like freezed,like it dont have suspension.
Any bump on the road and the motor just fly or “ricochet” (weird to say but i dont have better word)

You declare speed but do not assign a value to it, it is defaulted on 0. Except if you set it in the inspector.

You imported a 3D model, no suspension mechanics. You should write them.

You have added a RigidBody to your bike, thus it is affected by gravity. But if my memory is correct, its mass is by default on 1. Change this value to have it ‘fall down’ faster and thus have more realistic movements.

Do read here, check the different variables and functions it has