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