Three complete bikes from CRC and Wiggle over the last few years and all arrived happily in Southern Africa with tyres, forks and brakes all connected and at working pressure.
All in a regular bike boxes with some bubble wrap to stop rattling and rubbing. I have no idea if boxes by courier receive better treatment than baggage, but no significant damage to boxes.
All I had to do was fit wheels, handlebars to stem (levers, shifters, grips attached already) and the seatpost/saddle.
I’m assuming they came in a large plane to JHB and then on “a feeder aircraft” to the destination.
If you don’t depressurise everything for the flight then remember that Kenya has a variety of altitudes, so if the bike is assembled in Cape Town and you live in Eldoret you might have to adjust the tyres, shocks and brakes yourself, ditto if coming from Johannesburg to Mombasa or Lamu. 8)