Here is the full list of all 36 Knights And Bikes achievements.
Complete Day 3
Correctly fill the Jam Scone
Feed Honkers 25 times
Pose in the Cut-Out Standee in the Theme Park
Remove your Stabiliser Wheels
Unlock Bikes for both Demelza and Nessa
Complete Day 2
Complete Day 1
Find all the Treasure Tins In The Caravan Park
Keep Nessa's Throwing Disc away from her for 5 consecutive kicks
Avoid High-Fiving for 30 seconds when the other player is calling for it
High-Five when both players have a single point of health left
Wake up your knocked out friend
Find all the Treasure Tins In The Golf Course
Find all the Treasure Tins In The Wilderness
Drench all the Shrimps in the Harbour
Complete the Harbor arcade
Find all the Treasure Tins In The Harbour
Damage an Enemy with a splash of Goose Poop
Water all the Seeds in the Theme Park
Find all the Treasure Tins In The Theme Park
Wear the Haybale Armour
Boost into 10 Enemies on your bike
Spell "Bum" using the Wizard Tower
Attack an Enemy with a possessed Enemy
Have a dance party with 3 Enemies
Possess a Water Ballon and a Stereo with Demelza's Game Gauntlet
Find all the Treasure Tins In The Scrap Yard
Complete Day 4
Possess all the different types of Enemies with Demelza's Game Gauntlet
Find all the Treasure Tins In The Quarry
Complete Day 5
Activate the secret Pyramid in the Golf Course
Complete Day 6
Find 200 Loot in the Bushes
Cycle 100 miles