Simon Sorgedgrager successfully defended his MSc thesis titled Riding a Bicycle Without Hands: How To Do It and the Bicycle Dynamics Behind It on April 25, 2025. Simon created variations of bicycle rider upper-body models for use in the study of controlling the non-linear Carvallo-Whipple bicycle model. In particular, he developed a model of the rider's seat-butt connection that imposes a configuration constraint that better mimics the motion we have observed in no-hands riding. He also developed a triple pendulum model that includes motion of the head. He then solved optimal path tracking problems to find solutions for making lane changes, 90 degree turns, and staying on a straight path when subject to wind. He discovered several new and interesting things through these optimal control solutions:

• The rider uses less control energy to make a lane change with the new seat joint than typical pin joint pendulum models. This implies that the strategy of shifting the seat laterally under your butt is a more effective way to manipulate the roll angle of the bicycle.
• When subjected to lateral wind forces, the rider leans into the wind to maintain a straight path.
• A rider can make a turn without countersteering with carefully coordinated upper body contortions.

Simon developed all of the models with SymBRiM and solved the optimal control problems with opty. Simon's code is found at https://github.com/mechmotum/no-hands-riding.

The following animations show the rider model variations performing a lane change:

Classic single pendulum upper body rider model performing a lane change.

New single pendulum with laterally sliding seat-butt model performing a lane change.

New triple pendulum with laterally sliding seat-butt model performing a lane change.

The following videos show the comparison of turning with and without countersteering:

Triple pendulum model performing a turn with countersteering.

Triple pendulum model performing a turn without countersteering.

Simon was co-supervised by Jason K. Moore and José Farías. Everyone at the bicycle lab is very proud of Simon and wishes him the best in his next adventures.