extending axles?

[gizmo]

I want to make my bot 4 wheel drive by adding a sprocket I'm using 100mm blue wheels do I need to extend the axle and if so how

[jonny]

bolt the sprocket onto the wheel

[gizmo]

I understand that but would I do that

[Laser]

get the sprocket inline with the wheel and then drill 3 holes out and screw them together.

[jonny]

drill holes in wheel and sprocket and make sure they line up and the sprocket is in the centre and then use bolts to keep the sprockets there