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