Mid-drive motors mounted in downtube

BikeCAD includes several gearboxes and mid-drive motors that mount to the frame with some sort of bracket, bridge or node as they're sometimes called. However, BikeCAD version 24 is the first to feature the Vinka S30 which is a mid-drive motor that mounts inside the downtube. To configure the frame to accommodate this motor, select a rectangular cross section downtube. You'll need to make the downtube large enough in height and width to fit the motor. Also, while the convention with most bikes is to miter the downtube to fit around the seat tube, you'll need to click the toggle button in the tubing dialog box to specify that for this bike the seat tube should be mitered to fit against the down tube. Applying some amount of offset at the BB will provide extra material for mounting bolts. Increasing dimension L1 extends this extra material downward so that the chainstays can be attached. Finally, click the wall thickness icon for the downtube to specify the wall thickness as this will be reflected in the model exported to FreeCAD.