Here is the full list of all 23 Urban Trial Playground achievements.
Crash 100 times.
Perform 1,000 Tricks playing as Tommy.
Unlock Level 15.
Unlock Level 30.
Unlock all Levels.
Score 100,000 points in one Combo.
Score 300,000 points in one Combo.
Score 500,000 points in one Combo.
Get x10 score multiplier.
Get x15 score multiplier.
Get x20 score multiplier.
Score 250,000 points in one run on any Level.
Score 500,000 points in one run on any Level.
Perform 1,000 Tricks playing as Riley.
Perform 5,000 total Tricks.
Score 20,000 points by performing a single Wheelie.
Score 20,000 points by performing a single Stoppie.
Unlock all Motorbikes.
Complete all Levels with 5 star rating.
Complete all Challenges.
Collect all Chips.
Complete "Late 2 Gate" with zero crashes and without hitting the brakes.
Frontflip over the Hotdog in "Sup Dawg".