Hold the Wheel: Cycling Sim

Hold the Wheel is a cycling physics sandbox, not a game. There is no winning and no score. You configure a rider, clone yourself with a different mass or height, and watch what each version has to do to stay on the same wheel as the road tilts up and down. WHAT IT SHOWS On the flat at 45 km/h, aerodynamic drag is 80-85% of the power demand. Mass barely enters, drafting is a multiplier on your drag area rather than a flat saving in watts, and the limit is the lighter rider's absolute power. On a 6% climb at 20 km/h that aero term has collapsed by a factor of (20/45) cubed, gravity dominates, and watts per kilogram of total system mass rules instead. The gradient where those two swap is the single most informative number here, and it moves with speed: around 0.5% at 21 km/h, around 3.2% at 43 km/h. At the speeds a club rider actually takes a roller, nearly every riser favors the lighter rider. That is the intuition this is built to give you. HOW IT MODELS RIDERS Nothing here is a free parameter you can set to a flattering number: - Drag area is derived from height and mass through Du Bois body surface area, so a taller rider pays for the height. - Critical power scales with mass to the power 0.67, not linearly, so holding watts per kilogram constant across masses does not quietly make the heavy rider superhuman. - Anaerobic work capacity scales roughly linearly with mass, which is what makes repeated rolling terrain accumulate a real cost rather than washing out. - Drafting reduces drag area, so its benefit falls away on a climb exactly as it does on the road. - Kinetic energy traded for height cancels mass, and so does rolling resistance. Only aerodynamics breaks the symmetry between riders. If a result seems to favor the heavy rider through inertia alone, it is the model being honest, not a thumb on the scale. BUILD A ROUTE Lay out a course segment by segment - lengths and gradients you choose - and read off where each rider gains and loses. The whole run is computed up front, so you can jump to any point on the elevation profile and inspect it rather than waiting to arrive. NO ACCOUNTS, NO NETWORK Everything runs on the device. There is no sign-in, no analytics, no advertising, and nothing is uploaded anywhere. Your presets are stored locally on your phone.