automatic assist level based on slope. Anyone do this?

Hi,
First time poster, long time lurker. I'm about to take the plunge and pick up some components to build my first ebike. While obsessing about what kind of control system I'd go with (throttle, PAS, torque etc) it occurred to me that what I really want is simply a bike that rides like it's always on a slight downhill grade. My willpower is weak and I am lazy, so I basically want to force myself to use a certain consistent level of effort, and also minimize the button pushing and adjusting during a ride. Just turn on, hop on, and ride like it's a single-speed on the flattest, most windless place on earth (could add a headwind sensor too). I've seen mention of Stromer and Copenhagen wheel having slope sensors, but not much else. Seems like this would be a desirable way to ride, so I'm surprised I haven't seen more about it.
I figure this could be hacked with a conventional throttle by having a microcontroller with inclinometer control the throttle input. I don't have the time to take it that far, but thought maybe someone else has already explored this and found it lacking.
Patient feedback appreciated.

-sl_d

I feel like this is the case with the PAS from Bafang mid-drives and proper programming.
The set assist level determines the speed the motor will maintain.

Example:
You set the motor to PAS level X which is 30km/h.
You pedal at your usual pace which by itself would move the bike at 25km/h, the motor makes up the rest to reach 30km/h.
Now there's a slope ahead, your pedal input would only make you go up at 10km/h, motor does the rest. You can keep on pedaling at your pace, maybe have to shift down and pedal at a faster cadence.
After the slope there's a downhill section, the bike goes above 30km/h and the motor shuts off until the bike slows down to 30km/h again.

This works quiet well for me, add a gear and brake sensor + combine it with throttle and it's almost perfect for any kind of riding.

Thanks for the input on the Bafang, that sounds pretty close to what I'm looking for.
Thinking a bit more about it, I guess perfection would be a torque sensor to measure pedaling effort, so the rider controls overall speed with the legs (because sometimes you want to soft-pedal through areas like parking lots etc) and then slope and wind sensors to effectively eliminate those factors. And probably a lot of program tweaking to get smooth transitions.

sl_duck said:

Thanks for the input on the Bafang, that sounds pretty close to what I'm looking for.
Thinking a bit more about it, I guess perfection would be a torque sensor to measure pedaling effort, so the rider controls overall speed with the legs (because sometimes you want to soft-pedal through areas like parking lots etc) and then slope and wind sensors to effectively eliminate those factors. And probably a lot of program tweaking to get smooth transitions.

Click to expand...

Yeah, you can't really use the Bafang PAS if you want to go slow.
That's when I turn it off and use my legs only with some throttle maybe, HOWEVER they frocked up the throttle on their latest motors *!@?! -> https://endless-sphere.com/forums/viewtopic.php?t=93977

A torque sensor would be great for technical stuff, however even that could go wrong when you put your weight on the pedals.
It's sad that they didn't add one on the BBSHD, guess they want people to buy a custom bike with the max drive ..

Actually, I guess a torque sensor that is proportional to speed would eliminate the need for any slope sensor. On a steep hill, the system would try to maintain speed and naturally add power, and on flats, less power. Pedal more lightly to slow down. I bet the Cycle Analyst and Phaserunner could be configured to do something like this. Have to do some more reading....
From what I understand, most torque based systems simply magnify rider power, so a certain level of assist on a hill will result in you going faster for the same effort on the flats if you don't dial back the assist level.

Depends--if you are using a middrive, you're going to downshift to go slower, or to go up a hill, so the assist should still be ok at being proportional without any special sensors like inclinometers, assuming the motor speed is right for the gearing used.

However...most of the middrive systems are not torque sensors; I think the TSDZ2 is one of the few that does have one.


There are a few posts here and there about using inclinometers as or with throttles, if any of them help:
https://endless-sphere.com/forums/search.php?keywords=inclinometer*+throttle*&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Sounds like it would be great, if my right hand didn't already do it better. Learning to properly ride with a half grip throttle is priceless.

But many do fail to get used to it, particularly if they did not ride motorcycles in the past. The trick is to pay attention to the pedal pressure, and adjust throttle to keep that pressure perfect, for the gear you chose. Don't worry about speed, pay attention to pedal effort, and don't select too low a gear if riding a hub motor.

On the steeper hills, this is not too hard, you tend to just crank on full throttle, and then start downshifting into lower gears as needed. Pedal harder on the hill if needed, but never too hard, so you can keep it up if the hill is 10 miles long.

Or if commited to riding slow already, then you do have to keep modulating throttle. The key things are to not death grip the throttle, and use a half grip type. Long rides are possible without Pas, or hand fatigue. By long, I mean 5 hours or more.


If your system has 800-1000w, and your grades are not much above 5%, its easy. you stay in your highest gear, and maintain at least 15 mph up the hills with light pedal assist. BTW, your smart throttle idea, though a good idea, will not be able to vary the watts to match the wind. For me, the great thing about e bikes was not so much slaying the hill, but slaying the wind.


Just learn to ride throttle well, and you will see. Pick a gear, and pick a cadence for that gear. Adjust power using the fastest, best computer on earth, your brain. Its hooked to a torque sensor, the pressure your feet feel. Keep your cadence and effort stable through the whole ride. If you cant whistle or sing while riding, more throttle. It WILL take effort at first. But soon, like riding a bike, you won't be thinking any more. You will just automatically vary throttle based on the feel on the feet. Mild pressure, but not clown pedaling.

Thanks for the input Dogman. I have a tendency to allow the perfect be the enemy of the good, so your twist-grip setup is a good, simple starting point to get into it. I do have lots of motorcycle experience so a twist throttle will be familiar. I plan on going with a Bafang MG310 hub motor and Grin Baserunner controller to get my feet wet. My commute is only 16 miles rt with one short 5% hill.

I was curious about doing something like this, at least from the hill point of view, and I think it turned out to not quite be possible with the Cycle Analyst - I think I wanted to tie the proportional assist from the Sempu Torque Sensor up with the speed mode for the throttle (the one where position of the throttle is tied to speed). I think it might be one of those ideas that sounds practical but is perhaps not actually a good idea.

What I ended up with was just using the Aux Pot to adjust my assist level, and presets with ranges of 0-3x, 0-10x and 0-20x - so there's a little bit of thumbing a knob as I start climbing the hill, but from there it still feels relatively natural.

I never wanted a throttle only bike, but off-and-on that's what I had, and I was surprised at the extent to which it was fine. Not quite as nice, but still totally fine.