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