help with display


New member
Local time
12:46 PM
Nov 15, 2023
hello, I have an Engwe X20, it uses bc281 display from riding-evolved (digitech), the same as the x24, x26 and engine pro models.

I disagree with how pedal assist works, where the PAS level you select, just tells the motor apply power until a specific speed is reached.

I would like it to be like this:

The percentage you set in each PAS level, should tell the motor how much power must apply (based on nominal power), so if I set in PAS1 a 20% assistance, motor applies 150W of constant power (while I'm pedaling) (20% of 750W=150W).

Is it possible just tweaking the hidden menu?
Is it possible to reprogram the bc281 display to change this behaviour?

I very much appreciate any hint.
If I understand you correctly you are looking for a torque sensing system that provides proportional power to the "push" you provide with your legs.
PAS is ok but I really don't enjoy having to match my effort with the correct gear with the current terrain. It's doable but requires more thought.

I believe PAS works according to speed. PAS 1 will push until you reach x mph, PAS 2 is x+1 mph, etc.
I love Grin and their stuff.

I love Grin and their stuff.

Thanks for the link, very helpful info there!

I'm fine with cadence sensor, what I would like is to change the motor's behaviour, I mean, in the display configuration menu, level 3 assistance has the value "60%", first time I saw this, I thought it was referring to 60% of max amps or something like that, but after 25 miles riding this ebike, I see that this value, 60%, just equals to 15mph, so whenever you're under that speed, motor applies all the power avaliable to reach 15mph, and that's what I dislike.
I want to use assistance levels to control how much amps motor uses.
I love Grin and their stuff.

Searching in that link, I found exactly what I need, im going to paste an extract.
Engwe ebikes use Basic PAS, constant throttle, the second option, and I need to change it to the first option, Basic PAS, constant power.

Basic PAS, constant power​

This was the pedal assist approach used in the original "autoPAS" mode of the V3 CA device. Whenever the rider pedaled, a given amount of power was supplied to the motor. This power remained constant up to the speed limit of the system. With autoPAS set to 200watts, you would have receive the same 200 watts of boost even as you sped up or slowed down due to changing terrain or pedal power. When you adjusted the pedal assist level from the handlebar control, you would be directly increasing or decreasing this power setpoint.

Basic PAS, constant throttle​

This is a common approach by many turn-key ebikes since it doesn't require any internal control loop. The PAS assist setting is basically like the throttle setpoint, so when you pedal the bike at the 50% assist level it would be like riding with 50% throttle. This generally has the effect of changing the speed limit of the bike, with 50% assist the motor will only spin up to half the speed. At lower speeds than this the motor will be able to output full power, while at higher speed there wouldn't be any assist at all. This mode can be preferable to constant power PAS for people who want their assist level to effectively regulate the cruising speed of the bike, rather than the power drawn from the battery
From what I’ve experienced there is usually no other option with displays. If you can find a manual you can read to see if they allow changes but I believe you are stuck with what you have.
All the PAS (cadence based) stuff I’ve worked on gives full power until a certain speed is reached. Higher PAS number means the motor pushes until a higher speed is reached.
For your next bike look into torque sensing.
Although I can't give specific advice on your particular bike, in most cases the capability to make the changes you are proposing are not possible without considerable extra expense. You would have to change the display and controller for more ability to customize; or the cycle analyst from Grin may be a possibility.
It seems to me that a constant application of power would seriously reduce the available range.
I have found on my cadence type system that I need to find the proper gearing combination that is slightly above the speed setting for a given pas setting; that way most pedaling effort comes from my legs and I get a boost from the motor when encountering a hill. I realize not everyone wants to expell so much personal effort; in that case the throttle (if equipped) can be used to propel the bike completely under electric power or "ghost pedal" to keep the pas active.
Yes, with PAS, there is a "sweet spot" (I'm being sarcastic here) where the rider can "underpower" the desired speed by adjusting the PAS to the next lower level. The rider then pushes with their legs and shares the burden with the motor. It's not intuitive or ideal in my opinion.

Shout out to Grin for knowing all this and building the "DIY city on the hill" market.

The ENGWE looks like a 100mm bottom bracket (BB). If you are really wed to this bike you can get a Grin setup to allow torque sensing. You'll have to replace the BB, the controller and the display. Its not cheap or especially easy but it's doable. The beauty of the Grin controller/display setup is it can learn any motor and allows ALL SORTS off programming and customization.