bbs02 steep hill best practices?

[footloose]

It is a very bad idea to go up steep inclines with the bbs02 in a low assist level. .... Frankly, if a high PAS level is too fast for you to pedal, you'd be better off selecting the lowest gear possible and using the throttle to spun the cranks to a fast pace.

Thank you for real world experience based advice.
The right answer on setting PAS level for steep hills isn't completely intuitive.
My own approach to steep hills has been pick lowest gear, use throttle liberally, and contribute a bit with pedals when possible.
Haven't fried first gen controller so far using that approach, touch wood.

 

[Alan B]

The real test is motor and controller temperature. If they're not heating up, your technique is working. If they are getting hot, do something different or expect a failure.

 

[cell_man]

It is a very bad idea to go up steep inclines with the bbs02 in a low assist level. .... Frankly, if a high PAS level is too fast for you to pedal, you'd be better off selecting the lowest gear possible and using the throttle to spun the cranks to a fast pace.

Thank you for real world experience based advice.
The right answer on setting PAS level for steep hills isn't completely intuitive.
My own approach to steep hills has been pick lowest gear, use throttle liberally, and contribute a bit with pedals when possible.
Haven't fried first gen controller so far using that approach, touch wood.

You are welcome

It sounds like you are already doing what I would suggest, and you must be doing something right if you've ran an early model BBS02 kit for this long without a controller issue.

My feeling is that the PAS mode on the early model BBS02 kits did not have good current limiting and it didn't like to run at an RPM much lower than the typical cruising speeds (typically ~80% of no load). You would get funny things happening when pulling off from a standstill, when using PAS mode, as the motor speed increased, to where it wanted to run. In throttle mode, it wouldn't do this, the progress was smooth from a standstill, but it would deliver too much power, down low, at low rpm (IMPO). There have been improvements to the firmware over time and the operation is now much improved, but they still deliver too much power at low RPM, IMPO. The earliest BBS02 controllers were only 6 fet and were basically just a BBS01 controller with solder added to the shunt (Really!) to increase the max current by about 25% more than the max allowable program level (20A), but actually they'd be pulling 28A, through 6 very so so mosfets and with not so good current limiting. It's not so good a combination and unsurprisingly, they would often fail.

A middle motor gives the user the option to either use the motor very effectively, or to make it work really hard, by their choice of gears. Running on the flat, it isn't going to make a huge difference if you pedal at a slow cadence, but on steep hills, where the motor is working hard, you really should be using the gears to keep the motor rpm high.

 

[RVD]

the internal gear hub is a shimano nexus 8. it came with the bike (uptown breezer 8).

i do think the bike can probably make it up the hill in gear 1 without me pedaling. i do feel resistance when i pedal though. i usually bike up at gear 2 these days and i do help out by pedaling. last night on my way home it was using around 900 watts going up the hill.

as for the grade of the hill, i don't really know other than what strava and my garmin 705 tell me. it is one of the steepest hills in the area (seattle) and it is one of those hills where people walk up slowly. but it's not as steep as some of the hills that i have seen in SF where you need to downshift into 1st gear when you're driving a car. a car can make it up the hill fairly easily.

this is the segment on strava - https://www.strava.com/segments/637874 - says avg grade 17% for 0.1 miles so it's not long. most fast cyclists take 1-2 minutes to get up there but i think the avg cyclists will take more like 3-4 minutes or so.

i find that using assist level 9 and lowest gear 1 is the best to get up any steep hill. i haven't met one yet that this bike can't handle.