Indoor cycling can be an effective exercise option for your fitness goals. Participants work up a sweat with intense cycling movements choreographed to loud music. Indoor cycling can provide you with an impressive calorie burn while toning and sculpting your lower body. However, the way your thighs respond to this exercise will depend on a number of variables -- cycling isn't guaranteed to create slim thighs for everyone.
Genetics are the biggest factor in the size of your thighs. If you have a naturally muscular body or respond quickly to exercise, your thighs may actually become thicker as muscle growth is stimulated. Alternatively, if you have substantial fat around your thighs, they could become slimmer in size, even if your muscles grow, because you're melting fat away.