A few comments.
First, your Colsons are on backward. The features on one side of the hub are intended to prevent the wheel and hub from rubbing against the stationary parts of the bearing, entirely contacting the inner race. Having them on the outside defeats their purpose.
Second, it seems you have the exact same gear on the output of your ball shifter as you do in the gear drive line. In that case, why not face mount the Ball Shifter to the tube and have the second stage output drive the other gear? Your current setup is just redundant.
Third, I would be very concerned with just how much you're pocketing the top and bottom of the tube to make room for gears. Your tube's profile gets closer and closer to resembling a pair of thin plates, which is susceptible to bending. Bending would be the absolute worst thing for a gear drive, which relies on rigidity to work. Gears in a tube are not necessarily a bad idea, but you would want a bigger tube if you were to go that route.
Fourth, have you thought about how you'll actually get the gears in those slots? They are smaller than the diameter of the gear.
A good start, I just wanted to throw these out there to keep you working
