DISCLAIMER: This is to be used as an aid only, and does not replace a professional bike fit. The author will not be held accountable for anything that results from the use of this tool. Use at your own risk.
A simple tool that uses bike frame and person length measurements to visualise the user on a bike, and calculate current angles as the crank moves through a revolution. This allows multiple riders to be overlaid and plotted in different positions, to compare the effect of adjusting seat height and position.
There are two main configuration files, one for the bike, and one for the rider. The rider file allows multiple rider configurations to be set.
This defines the dimensions of the bike. "Required for rider" determines whether the length has an effect on the rider angles.
| Parameter Name | Required for Rider | Description |
|---|---|---|
| chainStay | No | The length from the bottom bracket to the center of the rear wheel. |
| wheelBase | No | The length between the centers of the two wheels. |
| wheelDiameter | No | The diameter of the wheel. |
| seatTube | Yes | The length from the bottom bracket to the point where the seat tube meets the rest of the frame. |
| seatStay | No | The length from the center of the rear wheel to the point where the seat tube meets the rest of the frame. |
| bototmBracketDrop | Yes | The vertical distance between the center of the rear wheel and the bottom bracket. |
| forkLength | No | The distance from the center of the front wheel to the point where the fork meets the rest of the frame. |
| downTube | Yes | The distance from the bottom bracket to the point where the fork meets the frame. |
| topTube | Yes | The distance from the seat post frame point to the front post frame point. |
| headTube | No | The distance from where the fork meets the frame to where the top tube meets the frame. |
| handleBarPost | Yes | The distance from the point where the top tube meets the frame to the top of the handle bar tube. |
| handleBarLength | Yes | The distance fro the top of the handle bar post to the front levers. |
| handleBar2FrontWheel | No | The distance from the front levers to the center of the front wheel. |
| crankLength | Yes | The length of the cranks. |
| leverLength | Yes | The length of the brake/gear levers. |
This can define multiple riders. Each rider must have the following defined.
| Parameter Name | Required for Rider | Description |
|---|---|---|
| seatLengthFwd | Yes | The length of the seat forward of the seatpost. |
| seatLengthAft | Yes | The length of the seat behind the seatpost. |
| seatRiderOffsetX | Yes | The horizontal offset of the rider hip joint from the seat/seatpost position. |
| seatRiderOffsetY | Yes | The vertical offset of the rider hip joint from the seat/seatpost position. |
| hip2ShoulderLength | Yes | The distance between the hip joint point and the shoulder joint point. |
| hip2KneeLength | Yes | The distance from the hip joint to the knee joint. |
| knee2AnkleLength | Yes | The distance between the knee joint point to the ankle joint point. |
| footLength | Yes | The length from the ankle joint to the toe. |
| footContactProportion | Yes | The proportion from the rear of the foot that the foot contacts the middle of the pedal. |
| pedalLength | Yes | The Length of the pedal. |
| shoulder2ElbowLength | Yes | The length from the shoulder joint to the elbow joint. |
| elbowWristContactLength | Yes | The length from the elbow joint to the wrist joint. |
| wrist2FingerHoldPoint | Yes | The length from the wrist joint to the point on the fingers that wrap around the levers. |
| hip2HorizontalAngleDeg | Yes | The angle, in degrees of the riders torso, to the horizontal. |
Update both bike.json and rider.json with your configurations, then run
python main.py
This allows the user to visualise the position through the crank cycle, and compare the maximum and minimum knee and hip angles for each configuration.