The rules
- Carry no more than one passenger (Nigeria Highway Code).
- Your passenger needs a helmet too, fastened properly.
- Don't carry oversized loads, or passengers holding them.
Brief your passenger
Ask them to hold on firmly, keep their feet on the pegs, lean with you rather than against you, and stay still at stops.
Ride differently
Expect longer braking distances and slower acceleration. Take corners more gently. Get plenty of solo practice before you carry anyone.
Sources: Nigeria Highway Code — The Motorcyclist