Newbie - please explain how to control the speed of a UK legal ebike?

Brummie

Pedelecer
Mar 18, 2018
55
9
58
Midlands
I'm a complete Newbie so please be gentle when I ask this stupid question...
I'm a little confused about how you control the acceleration & speed of a UK road legal ebike without a throttle? Assuming you set the power & max speed on the controller at the start of your journey, what stops the bike accelerating towards max speed every time you do the slightest pedalling? If you stop pedalling or touch the brakes, the power cuts and you slow down until you release the brakes & pedal. So how do you adjust the torque to achieve the actual acceleration or speed required, or is it literally as crude as the power is either on or off?
 
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Deleted member 4366

Guest
If you set the power to maximum, that's what will happen. That's why they have adjustable power levels. You set the power level to whatever you want (normally 5 levels, or 6 counting zero). Bear in mind that the power from a 250W system is not that much even on maximum, so it's not a problem to use max power all the time, except in say a pedestrian area, where you have to go slow. You can normally turn the power down to zero if you need to be very careful where you go.

Different bikes have different control systems. Some limit speed, with each level, some limit power, and some have both.
 

Brummie

Pedelecer
Mar 18, 2018
55
9
58
Midlands
Thanks d8veh. I haven't experienced the issue yet but I guess that the aggressive power on/off surge issue that i've imagined is more apparent on higher power motors.
 
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Deleted member 4366

Guest
Thanks d8veh. I haven't experienced the issue yet but I guess that the aggressive power on/off surge issue that i've imagined is more apparent on higher power motors.
It's more apparent on those that use speed control in the controller. Unfortunately most sellers wouldn't know what system their bike has, so you can only tell by trying, but generally, the cheaper ones use speed control, especially the ones with LED control panels and only 3 levels of assist.
 

Brummie

Pedelecer
Mar 18, 2018
55
9
58
Midlands
Thanks for the quick reply. I'm looking at getting the Swytch kit with the LCD controller. You can set the speed and/or the power level. Do you think that when the kit reaches the target speed it will surge on/off around the speed or modulate subtly (like car cruise control) to maintain speed.
 
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Deleted member 4366

Guest
That's a good question. The first demonstration kits had the Xiongda motor. Their original controller had a noticeable delay in both the throttle and pedal sensor; however, there's now a new version of motor and controller. Until somebody gets a production version of the Swytch kit, we can't say what you'll get, but what I can say is that it's not going to lurch off out of control.