I suppose that's what i meant by the above really, but using the throttle to set the cruise (while peddling) speed dynamically, as it were. Have you actually implemented a working cruise control
Does the throttle setting actually effect the output power when peddling (if it's set above zero)? I tend to use one or the other usually...
Mine works like this:
There's a three position switch that switches between cruise and normal throttle. In the middle position, neither are connected, so it works on the pedal sensor. Whatever speed you've selected with the cruise control knob is the speed the bike goes to when you throw the switch - whether you pedal or not. If you set a low speed - say 12mph - then, when you pedal past 12mph, you're on your own. The power tails off soon after 12mph, so you can go a long way with hardly any battery. When a hill comes, the bike starts to slow down, and when it goes below 12mph, the controller feeds in power in an attempt to maintain that speed. The slower you go, the more power is given, I think most cheap controllers work like this.
You cannot use this cruise control without brake cut-offs because it would be dangerous and even then, it's easy to forget it's on and let go the brake, wherupon the bike kicks forward with full power because it's present speed is way below the set speed.
I don't use my throttle anymore. I start off with the switch in the middle position for pedal sensor control only, and as soon as I'm rolling, I switch to cruise, and dial in the speed I want to go - normally 15mph. After that I use the brakes to control the speed. The brake switch comes on before the brakes have any effect, so the brake levers are like a sort of on/off switch, which is useful when things get a bit tight - pedestrians, etc.
It costs about £5 to make the cruise control. You need one 3 position switch, one 10k linear pot and a little box to put them in. You can get all of them from Maplin. You can see the control on the left handlebar in my picture of the Speedict in the Speedict thread. Here's the wiring schematic: