Here a diagram:
View attachment 82778
Explaining it:
- First gear will be on the right side of the wheel using a freewheel 44T sprocket (SBP has the freewheel adapter and sprocket), maybe a 48T if 44 is too small.
- Second gear will be on the left side of the wheel using a regular 40T sprocket.
- Centrifugal clutch will be as before on the shaft and will act as "freewheel" when on first speed.
- I'll use bike chains well lubricated and avoiding tensors as much as I can.
- Longer shaft will be hold on the right side with a jackshaft bearing to keep it in place.