Here is the full list of all 19 Race.a.bit achievements.
Unlock all achievements.
Beat a friend on a track you created.
Challenge a friend.
Race on a hundred community tracks.
Upload a track you created.
Upload ten tracks you created.
Upload twenty tracks you created.
Rate fifty community tracks.
Race on fifty community tracks.
Rate twenty community tracks.
Race on ten community tracks.
Rate a community track.
Win bronze medals on all official tracks.
Win gold medals on all official tracks.
Win bronze medals on at least half of the official tracks.
Fall of the edge.
Explode.
Rank in the top 10 of a highscore list.
Win a bronze medal on at least one official track.