Here is the full list of all 33 MX Nitro achievements.
Take First place in any race.
Rode to finish without crashing.
Complete 50 challenges.
Complete the First Tournament.
Get level 3.
Win a race with a half-wheel lead.
Win a ranked race.
Perform only Fresh tricks in Freestyle and win.
Collect all stars in Online Race.
Finish a race with 108 seconds time.
Made a flashy finish.
Buy and equip a new customization item.
Get and equip Enforcer set.
Perform Superman 50 times.
Perform all 4-button tricks in the game at least once.
Speed up to 180 km/h on Drag.
Get 5000 Trick Score in one combo.
Spent a total of 5 minutes in midair.
Fly 200 meters in one crashflight.
Found his Doom.
Collect all Track Quest's marks.
Drive 1000 seconds on rear wheel.
Earn a total of 50000 credits on Slums races.
Buy all bikes.
Get full Nitro Tank 100 times on Desert tracks.
Overtake a total of 100 riders.
Crash 300 times.
Hoard 500 000 credits.
Beat Pedrolino.
Beat Punk Lizard.
Beat Steelhead.