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