Pedal Assist and Gear strategies

[BigNerd]

I think @Lightning P38 is my twin. I also did the same thing, figured out the max speed for each PAS level and then adjust accordingly with whom I'm riding with.

Most of the time I'm in PAS 0, I use PAS 1 or 2 for inclines and rarely go to 3 or higher. I know 1 is 10mph, 2 is 15mph I think 3 is either 17 or 18mph and not sure about 4 and 5 (although I can assume 5 is 28mph).

 

[AHicks]

Just a quick note here. Not all e-bike controllers use PAS levels that are speed based like that. There are some that are power based, where you select the amount of assist you want. That amount of assist will not change, no matter the speed. An example might be in PAS 1 say, you get about 80+/- watts of assistance (not much!). You'll have that same 80 watts of assistance at 6-8mph or 18mph. Speed has no effect. If you want/need more assistance, you go to a higher PAS level. Works GREAT!

 

[minigrrl]

That's the way I do it too - max speed for each PAS level. My partner on the other hand, he just leaves it on Level 6 (highest) ALL the time and starts and stops pedaling. His motor cutting in and out drives me CRAZY. Of course, my goal is to get exercise (i.e. my goal is to keep the bike at a speed where the motor isn't working and it's all me) where his goal is to not expend any energy if at all possible! Ha!

 

[RecBiker]

Just a quick note here. Not all e-bike controllers use PAS levels that are speed based like that. There are some that are power based, where you select the amount of assist you want. That amount of assist will not change, no matter the speed. An example might be in PAS 1 say, you get about 80+/- watts of assistance (not much!). You'll have that same 80 watts of assistance at 6-8mph or 18mph. Speed has no effect. If you want/need more assistance, you go to a higher PAS level. Works GREAT!

How would I know or how can I find out if my controller is speed based or power based?

 

[RecBiker]

Also, I learned from the bike at what speed the bike would go at each assist level with me pedaling.
For example, at assist 2 the e-assist maxes out at 10 mph on a level paved trail. At level 3 assist, it maxes out at 15 mph. At level 4, 20 mph. At level 5, 28 mph.

So if my buddy is riding at 10 mph on a non e bike, I know I will be able to keep his pace at level 2 assist.
As a 20 year cyclist, I always start out with the shifter in low gear like regular bikes, and shift up to the desired speed. My shifter does not display what gear I am in, I just know by feel about how many gears to shift up...and in this case about 3rd or 4 th gear.

If a buddy is riding at 12 mph, I will run out of assist on level 2 at 10 mph, but at level 3 I will be going too fast, so I have to decide whether I want to work without much assist at level 2 assist, or pedal and coast with level 3 assist. So with level 3 I pedal one or two revolutions, then coast a bit, then repeat.

The other day I was on a gravel rail trail, which reduced my speed about 2 mph, with some mature riders. So I used level 2, and it was a good match as they were going 8 mph on the 2% upgrade segment of the ride.

If I am solo on a paved trail, I will use level 3 and cruise at 15 mph. On some segments I will bump up to level 4 and cruise at 20 mph as I seem to be motivated to pedal harder and get another mph or two at the higher speed.

The only time I use level 5 is in traffic in downtown Scranton, as it boosts you off the line as quick as the cars, and I can cruise with them up to 28 - 30 mph.

How do determine the max speed for each pedal assist level? Won’t it change if you are climbing, descending, or riding on flat land, or what gear you’re in?

 

[theemartymac]

How do determine the max speed for each pedal assist level? Won’t it change if you are climbing, descending, or riding on flat land, or what gear you’re in?

It's just the 'target' the bike wants to hit before it backs off the power. If you are climbing and you can't hit the target speed for the PAS level, it won't stop applying the power. If you are coasting downhill in excess of the speed, it won't engage regardless of pedal cadence or torque.

You can determine it on level ground with some experimentation, and expect the cutouts to occur at that speed regardless of gear selection or effort. My experience with both my Bafang bikes (one 750w hub, one Ultra mid) are consistent with this, and the PAS settings equate to a very rough 10km/h difference at each level.

 

[RecBiker]

It's just the 'target' the bike wants to hit before it backs off the power. If you are climbing and you can't hit the target speed for the PAS level, it won't stop applying the power. If you are coasting downhill in excess of the speed, it won't engage regardless of pedal cadence or torque.

You can determine it on level ground with some experimentation, and expect the cutouts to occur at that speed regardless of gear selection or effort. My experience with both my Bafang bikes (one 750w hub, one Ultra mid) are consistent with this, and the PAS settings equate to a very rough 10km/h difference at each level.

I know what it feels like when the PAS kIckes in when I start peddling and I know what it feels like when the PAS drops off when I stop peddling. What should it feel like when it drops off while peddling? Someone else mentioned some controllers are powered based. How would I know if my controller is speed based or power based?

 

[theemartymac]

On mine I can tell by the noise, but also the little feeling of the 'push' disappears suddenly. The bafang motors seem to be all or nothing, with full output until they hit the limit, then shut off. It's far more noticeable at lower speeds as the bike gives 100% power until it hits the speed and then coasts. At higher speeds where the motor is already struggling to maintain the output (i.e. above 40 Km/h) it's less dramatic, but on a slight down hill I can feel the coast kick in and the motor goes quiet right at that speed.

Google your bike of course to see what system it has, but otherwise test it on flat level ground and see if there is a consistent top speed increase with each setting.

 

[RecBiker]

On mine I can tell by the noise, but also the little feeling of the 'push' disappears suddenly. The bafang motors seem to be all or nothing, with full output until they hit the limit, then shut off. It's far more noticeable at lower speeds as the bike gives 100% power until it hits the speed and then coasts. At higher speeds where the motor is already struggling to maintain the output (i.e. above 40 Km/h) it's less dramatic, but on a slight down hill I can feel the coast kick in and the motor goes quiet right at that speed.

Google your bike of course to see what system it has, but otherwise test it on flat level ground and see if there is a consistent top speed increase with each setting.

This is an excerpt from my e-bike’s manual. Can you tell if my pedal assist system is speed based or power based?

 

[Gordon71]

How would I know or how can I find out if my controller is speed based or power based?

On the lower part of my screen it shows the amount of power being used. I tend to use PAS3 mostly (I have 5 levels) It reads in the 350 watt range. A little higher when the battery is fully charged and a little lower later in the ride as the battery depletes. PAS5 reads the max at nearly 750watts.

 

[AHicks]

How would I know or how can I find out if my controller is speed based or power based?

Set it for PAS 1 and go ride it. While pedaling, accelerate until you feel the motor assist taper off. My bet is that speed will be in the neighborhood of 8-12mph, maybe a little less as I know you have the smaller wheels, right?

If you do not feel the motor assist tapering off, or see it if you have a real time watt meter on your display, you have a power based PAS. If you do feel/see it, you have a speed based PAS.

Do the same for PAS 2, and 3 so you have the answer to your "what speed" question as well.

 

[theemartymac]

This is an excerpt from my e-bike’s manual. Can you tell if my pedal assist system is speed based or power based?
View attachment 69772

It's a cadence sensor as it clearly states the sensor is behind the bottom bracket and starts with rotation. Torque sensors are inside the bracket on the crank arm as they are pressure sensors and start with load. It also says the motor cuts out at 20mph, so it's top speed-limited (governed). To see if the power outputs can actually change with PAS setting, try an acceleration test in each PAS level, and see if the initial kick in the pants is noticeably stronger for the first 10-15 km/h.

It would surprise me greatly if that bike had a variable output controller, vs the simpler speed-based cutoffs that can be easily measured with a cadence sensor, and at it's price point it would be unusual to have dual-mode options (Cadence AND Torque) but maybe a tech or dealer reading the forums will know more...

 

[AHicks]

It's a cadence sensor as it clearly states the sensor is behind the bottom bracket and starts with rotation. Torque sensors are inside the bracket on the crank arm as they are pressure sensors and start with load. It also says the motor cuts out at 20mph, so it's top speed-limited (governed). To see if the power outputs can actually change with PAS setting, try an acceleration test in each PAS level, and see if the initial kick in the pants is noticeably stronger for the first 10-15 km/h.

It would surprise me greatly if that bike had a variable output controller, vs the simpler speed-based cutoffs that can be easily measured with a cadence sensor, and at it's price point it would be unusual to have dual-mode options (Cadence AND Torque) but maybe a tech or dealer reading the forums will know more...

The point I was making applied to cadence sensor systems, the fact they are not all the same. Some are one way or the other (speed based or power based), while others, like the KT systems and the bigger Bafang mid drives, you can set according to your druthers. I do agree though, most inexpensive e-bikes are going to use speed based systems. I was splitting hairs.... -Al

 

[Jeremy McCreary]

Feeling for heat can be a red herring. Most hubs don't use the housing to actively cool the windings as there is an air space between the windings and the case. (Google or search here for 'Statorade' and 'Hub Sinks' for a rabbit hole of science on how different hubs and cooling options work/don't work) And the specific hub, drive type, and construction (direct/geared/etc.) plays a role, but for a normal sized human on a typical bike, you have to work hard to overheat one to the point of permanent damage, and normally it will cool off and resume performance.

First sign is usually power drop off, then perhaps 'cogging' where the power pulses, then heavy feeling pedals before it fails and faults out. It's important to note that they often cool slowly, and once hot, they soften and can fail over time due to repeated cycling and eventual hardening and cracking of the wiring. For a supersized guy like me, with heavy cargo, or seriously hard hills, it can be done much, much easier, especially if done repeatedly.

Watch this guy for a fun redneck science video that shows the effects of heat and cooling (although on crazy aussie customized bikes).

Living below the Equator is no excuse for driving on the wrong side of the road. Just sayin'.

Very illuminating video. I like the engineering part, too.