The topic of this thesis is design of NuVinci variator. This type of variator contains input disc which drives the spheres. They rotate around an axle which has the ability of changing the tilt. By changing the tilt, the transmission ratio changes too. The change of transmission ratio is continuous, with no stepping. The spheres drive the output disc. The task is to design NuVinci transmission appropriate for bicycle mounting. It is necessary to consider the power that can be transferred with this variator and which is applicable for bicycles. The transmission ratio also needs to be adapted for bicycle usage. Strength check, alongside with other needed calculations is to be done by valid standards. The paper begins with introduction which covers basic information about transmissions, types of variators and materials used for friction transmissions. The introduction is followed by a short description of a NuVinci variator made by Fallbrook Company. Introduction to the task is given next. Following that are calculations of the most important parts of this variator: friction bodies, axles, spring, bearings and bolts. The thesis ends with a conclusion and by listing all used literature, after which technical documentation of the final design is given.