Smoothness is key....
Riding quickly with a pillion is not the issue, it's how you get up to speed and back again.
If you've got one, a top box will undoubtedly give any pillion that added physical and mental security. No top box and a hand full of throttle, and they'll certainly feel like they're going to fall off the back.
We usually brake, sort of 75/25 front/ back. Now you have a pillion, you have much more weight over your rear wheel, so you can redistribute your braking, and use more rear.....
Take control of them getting on and off. If they jump on and you're still fiddling with the cuff of your jacket, you'll both end up on the floor.
Good advice Giles
Get your pillion not to get on until you tell them to do so, and more important not to get off until you tap them on the knee
Ask them to look over your left shoulder for a left hand bend, right shoulder for a right hander ... that will suffice to start with


At least when she does, I know that she hasn't fallen asleep (which she does very often)..