BBSHD Performance Settings (slightly refined)

In BBSHD Programming for the Pedaling Cyclist, I laid out what my preferred settings were for my ebikes. I have settled upon them after a fair bit of tinkering over time. Since that was published, I have made some refinements.

I’m going to skip all the background I went into before. None of those details have changed. I’ll just note what I have done, and what it seems to accomplish.

Remember, There is no one perfect suite of settings for the Bafang BBSxx series of motors. Most likely, your perfect setup will take a bit from here and a piece from there to give you exactly what you want. Use what you see here as a basis for your own experimentation.

In fact, I don’t even have a single flavor I stick to as you will see below.

The Basic Screen

From then to now, I changed nothing on this screen, and I’m only showing it here to give you a complete settings reference in one place.

The Pedal Assist Screen

There are several changes here, all geared to toning things down and making behavior more gentle. I have two versions of this screen in play on different bikes. The first is the more general-use, but the things I get from Version 2 could be very desirable on any bike.

I can’t say enough that there is no one best choice of settings for your BBSxx motor.

Version 1

This config change is just here to show a couple of settings and discuss what they do.

BEFORE on the left. AFTER on the right

Pedal Sensor Type

Some motors come programmed with BB-Sensor-32, others with DoubleSignal-24. Depending on who you ask, BBSHD motors have 24 sensor signals per rotation, which seems to indicate DoubleSignal24 is the proper setting. I have tried them both and can tell no difference from one to the other.

Start Current

This has been reduced to 4 from 6. Start Current dictates how much juice goes to the PAS system when it initiates. A lower number means a lesser ‘jerk’ on the drivetrain as the PAS system engages. This is a percentage number, so we are going from 6% to 4%. Restated, that is from ‘gentle’ to ‘more gentle’. Still, as small of a change as is indicated by the numbers, its effect is noticeable.

Start Degree

This has been increased from 4 all the way up to 10. Start Degree is the number of signal points that are crossed (as you turn the crankarms) before pedal assist engages. A full rotation of the crankarms equals 24 signals, so I have kicked up the pedal assist engagement from a 1/6 turn to almost a half-turn.

This can come in handy when I am at a stop light, but I stopped several car lengths back from the actual intersection. I can then stay in the saddle, balanced, and slowly turn the crankarms a bit at a time to maintain my balance and crawl forward. If I do it right, the light turns green before I reach the edge of the intersection, whereupon I can start pedaling in earnest to move forward, without having to dismount (and then re-mount) the bike.

NOTE: This technique only works when you are on flat ground.

Current Decay

This is set to maximum now, meaning the system pretty much doesn’t want to cut back power as cadence increases; virtually disabling the cut-back feature from the Basic screen, which conserves power (if you can spin the crankarms superfast, you don’t need assist). This is a setting I will very likely continue to play with. If I set it to the minimum of 1, then the motor will aggressively reduce the provided power as cadence increases. A lower setting is much more in tune with the pedelec ‘philosophy’ which I usually stick to. So don’t be too surprised if you come back in a month and this text has been supplemented with talk of a different, much lower setting.

UPDATE: May 19 2023 – Its been a lot more than a month, and it turns out Current Decay is not well suited for hill country, where it is part of a suite of settings that cut power when cadence is high. Crawling up a hill in a granny gear – both on a hillside singletrack and on a city street – is not the time for a power cutback regardless of your cadence level. On flat ground, a Current Decay of 4 is indeed part of a cyclist-friendly exercise regimen where power gets cut as cadence increases.

Version 2

Version 2 is a riff on Version 1 above. Its what I use on my flat-land-bound 2wd/awd Bullitt cargo bike.

‘Before’ on the left is the Version 1 ‘After’ screen just above in Figure 2. On the right is Version 2

Start Current %

This value is reduced to two percent. Gentler is better for startup, with no real downside. One thing I have noticed, going down to 2% versus 4%: pedaling there is a slightly noticeable lag in performance; ever so slight. I’ll take that as it is a sign my motor settings are taking it very easy on my drivetrain, and this is part of why I have such long-lived chains and cassettes (3400 miles and counting on my Lizzard King’s original 11-speed chain as of May 2023).

Slow Start Mode

The slow start mode – the strength of the initial punch the motor gives out when it fires up – stays down at ‘3’. This is the lowest number that is agreed to be safe for the BBSHD controller based on other sources. This setting is part of keeping the BBSHD gentle on your drivetrain and eliminating wear and tear.

Start Degree

In Version 1 I have this set so that there needs to be just under a half rotation of the cranks before the slow-start of pedal assist engages. When all of the settings are taken in together, it typically means pedal assist doesn’t begin to be felt until the bike crosses a 5 mph speed (If I want assist earlier there is always throttle).

In Version 2, I have reduced this to a 1/6 turn of the crankarms. The idea with all of these settings put together is that assist from the rear motor starts faster – Remember, on this bike the BBSHD is supplemented by a front motor that starts almost instantly from a stop, so the BBSHD is not trying to haul a bike up from zero on its own. On such a big, heavy cargo bike, some assist from both wheels asap is a good thing. Net result is that with two motors, I can get a good result from pure pedal assist without having to resort to the battery-sucking throttle. I start pedaling and the bike safely glides forward even if its weighing 400+ lbs.

Current Decay

This is a full 180 from Version 1, where Current Decay is set to do as little as possible, meaning the motor is the least likely as it can be to pull power as your cadence increases. Here, it is at its next-most aggressive setting. In part this is informed by the fact that there is a front hub motor (running off the same common battery) that – if faced with a sudden power drop from the rear motor – will still provide forward assist, and in practice that means it will increase wattage as its workload increases. This is part 1 of 2 of this story, with Part 2 being …

Keep Current %

The amount of assist that is retained when Current Decay pulls power back has been reduced to 30%. So the two settings together make it more likely that, as cadence increases, power will be reduced, and the amount of power that will continue to flow has further been reduced by 25% from its previous (fairly low) value.

Got all that? Here’s what the rider feels: Not much. Despite my characterization of these changes as ‘aggressive’, which they are if you just look at the numbers onscreen, reality is the result is muted. We’re using a little less power, which we don’t miss much, and that is going to give us a bump in range. At 20-25 mph, pedaling strong at 60-70 rpm cadence, the BBSHD on flat ground is eating about 200-250w on the typical Assist Level 4 and 225-275w at Level 5. Thats pretty light (power consumption will be more on a bike with just the BBSHD for a motor!)

If you want to have the motor back off when you demonstrate you don’t need it (if you did you couldn’t spin your legs and the crankarms) the Keep Current and Current Decay settings are your go-to’s to reducing power consumption and increasing range.

Thats It?

Yup thats it. At this point in the development of what I like and dislike on a BBSHD setup.