Electric Bikes - Bicycle math

I am going to install a hub motor on my beach bike. I will also have a 5 speed hub gear with it. If I use the cruise control set to, say, 15 mph and then pedal will:

1. The bike go faster - assuming that I am pedaling fast enough to warrant it going faster

or

2. Will the motor slow down because it senses another power source so that the bike is still going 15 mph

or

3. Some other option that I have not thought about?

Is this controller dependent?

i would expect a cruise control system to respond to pedal-power the same way it responds to a downhill-- if the bike accelerates above the set speed, the cruise control will cut back the power until you're back at the set speed (15mph).

I also assume the cruise control will not prevent you from going above 15mph on pure pedal power, but if you're pedaling hard enough to go 15.5mph then the motor won't do any of the work.

Somehow, I kinda expect cheap cruise things to simply hold a throttle position.

What cruise control system were you looking at?

I am going to install a hub motor on my beach bike. I will also have a 5 speed hub gear with it. If I use the cruise control set to, say, 15 mph and then pedal will:

1. The bike go faster - assuming that I am pedaling fast enough to warrant it going faster

or

2. Will the motor slow down because it senses another power source so that the bike is still going 15 mph

or

3. Some other option that I have not thought about?

Is this controller dependent?

It would be controller dependent.

A simple "open loop" controller will just provide a fixed duty cycle/average voltage to the motor, e.g. 50% duty cycle at 50% "throttle". You start pedaling, the bike will go faster. A variable speed electric drill has this type of controller.

A sophisticated "closed loop" controller will actually sense the speed and adjust motor power to maintain the speed. You start pedaling, the system will reduce motor power to maintain speed. A car cruise control is this type of controller.

I don't know what type most bicycle controllers are, but the open loop is much simpler/cheaper...

Thanks! I have not gotten around to looking at brands yet. When I started thinking about an ebike conversion project I thought it would be simple...boy was I wrong!