Here is the full list of all 35 Shredders achievements.
Complete 10 gaps
Ride 10 km of deep snow
Get a Score of over 6666 in a single trick
Transfer 3 rails
Unlock all the gear in the game
Complete The Village Roof Run Mission
Complete the Canyon Jump Mission
Spin a total of 360.000
Jump over the Rugby pole at the park
Ride 10 km with the snowmobile
Call the snowmobile 50 times
Rock the invitational!
Complete the We Own The Sky Mission
Complete The Lawn Darts Mission
Collect 10 collectibles
Jump 1000 times
Complete The Dammed Mission
Complete the Hit The Streets Mission
Bail 100 times
Complete the Spin Dizzy Mission
Complete the Factory Worker Mission
Complete the Forest Cross Mission
Ride 50 km
Complete The Beat The Street Mission
Collect all the SHRED letters in a mission
Land a 1080
Land a double backflip
Complete the Fast As Hell Mission
Land a 540 Indy
Complete 25 gaps
Collect 40 collectibles
Call the snowmobile 500 times
Complete the Cliff Drop Mission
Complete the AirBorne Mission
Play in a private session