Theory:

Factors affecting friction:
 
There are three factors that can directly affect friction between two bodies or surfaces.
  • Nature of area
  • Weight of the bodies and
  • Area of contact
Nature of the area:
Riding your bicycle on the road is much easier than riding over the beach sand or over snow. It is due to the nature of the area, i.e. road is a smooth surface whereas sand will have small stones and pebbles, making the friction between tyre and sand higher. Hence, the cycle cannot move smoothly. This is how the nature of the area influence the frictional force.
 
101001624_7f1e1a4ba2_o.jpg
A cyclist riding over snow surface
  
Weight of the bodies:
It is easy to ride your bicycle without any load. But, when you take your friend for a ride or when you ride your bicycle with a load, it becomes difficult for you to pedal. This is because as weight increases, the friction also increases. Since friction is a force that opposes the motion of the body, it becomes difficult for you to pedal.
 
cyclewitloadjpg.jpg
A bicycle without load
  
Area of contact:
Take a birthday cone. You can observe two ends, a small circle and a big circle.
  
birthdayconejpg.jpg
Cone
 
If you keep the cone in a table with a bigger base, it will be stable, but when you try to place the same with smaller end it will be difficult. If the area of contact is bigger, the friction will be more and hence the cone will not move. Whereas, if the area of contact is less, the friction will be lesser, and hence the cone will not be stable.
Reference:
https://www.wallpaperflare.com/search?wallpaper=birthday+hat
https://www.flickr.com/photos/bike/101001624
https://upload.wikimedia.org/wikipedia/commons/0/01/Market_porter_pedals_jugaad_goods_carrier_tricycle_in_Thoothukudi%2C_Tamil_Nadu%2C_India.jpg