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