How can I turn the direction of bicycle in Unity?

Hi I am new to the Unity and I am making Bicycle project in my school. I am facing a problem regarding turning the bicycle. I am attaching the YouTube link for the video which I made in which you can see the problem. I am also copying the C# Script below. Please help me through this.

YouTube Video Link : https://youtu.be/Xbd4ejR_4cY

Thank You

C# Script:

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class player : MonoBehaviour { public Animator anim; public Rigidbody rbody; private bool run;

 private float inputH;
 private float inputV;

 void FixedUpdate(){
     Rotation ();
 }

 private float wantedYRotation;
 private float currentYRotation;
 private float rotateAmountByKeys = 2.5f;
 private float rotationYVelocity;
 void Rotation(){
     if (Input.GetKey(KeyCode.LeftArrow)) 
     {
         wantedYRotation -= rotateAmountByKeys;
     }
     if (Input.GetKey(KeyCode.RightArrow)) 
     {
         wantedYRotation += rotateAmountByKeys;
     }
     currentYRotation = Mathf.SmoothDamp (currentYRotation, wantedYRotation, ref rotationYVelocity, 0.25f);
 }


 // Use this for initialization
 void Start () 
 {
     anim = GetComponent<Animator>();
     rbody = GetComponent<Rigidbody> ();
     run = false;
 }
 
 // Update is called once per frame
 void Update () 
 {
     if (Input.GetKey (KeyCode.LeftShift)) {
         run = true;
     } 
     else 
     {
         run = false;
     }

     inputH = Input.GetAxis ("Horizontal");
     inputV = Input.GetAxis ("Vertical");

     anim.SetFloat("inputH", inputH);
     anim.SetFloat("inputV", inputV);
     anim.SetBool("run",run);

     float moveX = inputH*100f*Time.deltaTime;
     float moveZ = inputV*100f*Time.deltaTime;

     if (moveZ <= 0f) 
     {
         moveX = 0f;
     }  
     else if (run) 
     {
         moveX *= 2f;
         moveZ *= 2f;
     }

     rbody.velocity = new Vector3 (moveX, 0f, moveZ);
     
 }

}