Three-wheel bicycles for senior citizens are safe to use. Having that third wheel provides a degree of balance and comfort that two-wheelers cannot. Three-wheel bikes allow seniors to remain active and fit through cycling as many of them cannot use a two-wheeler anymore.
One trend among many seniors is to move from an upright bicycle to a recumbent bicycle. This bicycle allows the rider to sit and lean back rather than hold up one's torso while riding. This difference allows many seniors to ride for years after they would have had to stop otherwise. The exercise benefits with a recumbent bicycle, though, are still plentiful.
With a third wheel, whether the bike is upright or recumbent, the need to maintain balance for the bike is gone. The rider can rely on the structure of the bike to remain up and moving, and all he has to do is focus on powering the bike. The possibility of losing the edge in a turn, or losing one's balance because of a slight distraction, is not nearly as high with a three-wheel bicycle as it is with a two-wheel bicycle, making it safe for seniors who are still looking for that cardiovascular boost with less danger of a tumble.