BBS02 Question.... Minimum Cadence for Safe Motor Operation / Temperate?

Ridetoglide

Member
Region
USA
Hey Guys... What would you say the minimum cadence/pedal rpm would be to protect the BBS02 motor/controller from over heating?

I noticed when my wife rides her cadence often is between 50 to 60 rpm while in pedal assist 2 and 3 ( out of 9). In comparison I generally always keep my cadence at least 70 and usually closer to 80 rpm.

For reference I have PAS 2 and 3 programmed to 20% and 30% current respectively and speed programmed to 54 and 58% respectively.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
MY opinion (an admitted old fart) regarding overheating - is that it's WAY more about how many watts is being pulled than it is about cadence. Fewer watts is less load on everything - and it can be easily viewed on most displays. Learn to cover that same ground while pulling fewer watts = better battery mileage.

BBS02 is good for an easy 750 watts. 1000w for a short burst if you need to.

Adjust the wattage being consumed at any point by adjusting PAS level and the gear you're in.

From a fitness perspective - can't help you. I ride 'cuz I like to, not for fitness. ;)
-Al
 

Dewey

Well-Known Member
Al's right, if you look at Justin's Motor Simulator https://ebikes.ca/tools/simulator.html and click the Middrive button, click the motor field at the top and scroll all the way to the bottom to select Show All then select the Bafang BBS02, and play with the values eg select an approximation of the battery and gearing you use, 25a controller, and increase the grade to say 9%, scroll down and in the Chart options change the x-axis to RPM, then click Simulate, you will see at lower RPM's the motor consumes less power and so will heat up less quickly. In the Performance box on the right at the bottom the final temp is the estimated temperature of the motor after running at these values after 2 hours. A neat feature is you can click Open System B to add a second motor to compare, like the Bafang BBSHD, or another BBS02 with different values, eg increase the grade % will see the load line and final temp increase as the amount of power required to ride in those conditions increases.
 

Ridetoglide

Member
Region
USA
Al's right, if you look at Justin's Motor Simulator https://ebikes.ca/tools/simulator.html and click the Middrive button, click the motor field at the top and scroll all the way to the bottom to select Show All then select the Bafang BBS02, and play with the values eg select an approximation of the battery and gearing you use, 25a controller, and increase the grade to say 9%, scroll down and in the Chart options change the x-axis to RPM, then click Simulate, you will see at lower RPM's the motor consumes less power and so will heat up less quickly. In the Performance box on the right at the bottom the final temp is the estimated temperature of the motor after running at these values after 2 hours. A neat feature is you can click Open System B to add a second motor to compare, like the Bafang BBSHD, or another BBS02 with different values, eg increase the grade % will see the load line and final temp increase as the amount of power required to ride in those conditions increases.
Lol... A motor simulator? that is awesome, I will definitely check it out
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Most of us that have messed with that tool enough to make it do what we want have found it's INCREDIBLY accurate. Well respected by all, and very worthwhile when trying to answer about any question that has to do with e-bike performance. Mess with it when you have a chance and get to know it....
 

tomjasz

Well-Known Member
The BBS01 and BBS02 need to be ridden like an acoustic bike. Proper gear use and they're great motors,
Chainring size can also create a problem. AHicks makes a good point.
is that it's WAY more about how many watts is being pulled than it is about cadence. Fewer watts is less load on everything - and it can be easily viewed on most displays. Learn to cover that same ground while pulling fewer watts = better battery mileage.
I road with a battery watt meter and saw exactly what AHicks described. I'm firmly on the 42T limitation for most riders.
 

Ridetoglide

Member
Region
USA
The BBS01 and BBS02 need to be ridden like an acoustic bike. Proper gear use and they're great motors,
Chainring size can also create a problem. AHicks makes a good point.

I road with a battery watt meter and saw exactly what AHicks described. I'm firmly on the 42T limitation for most riders.
Yes I actually replaced the 42T on my stunner X with a 36T, I lost some top end but I use the new lower gear a lot. I can get away with like 12 mph in assist 2 ( out of 9 ) ( my assist 2 is programed to 20% current and 54% speed ). I dont have a watt usage indication on my C961 display but i can tell it is a very efficient setting/configuration.
 

Ridetoglide

Member
Region
USA
42T is the smallest with offset. 36T is essentially flat. Lekkie does offer a 40T it’s rather expensive and needs additional components.
Why do you need the offset? With the 36T Lekkie my chain is just about straight in 5th gear which is the middle of the cassette.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I'm using a 44th and at next chain replacement I'm going back to 46th, both without issue.
But on the question of cadence and overheating.. Mr. Hicks and Mr. Tom J. are correct. Cadence is almost irrelevant and proper gear selection, PAS selection and monitoring current draw is what affects the motors performance and any over heating.
 
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Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Why do you need the offset? With the 36T Lekkie my chain is just about straight in 5th gear which is the middle of the cassette.
The stock chainrings are offset to maintain chainline to the rear cassette. Some of the aftermarket rings require spacers to do the same.
 

Ridetoglide

Member
Region
USA
The stock chainrings are offset to maintain chainline to the rear cassette. Some of the aftermarket rings require spacers to do the same.
For some reason with the stock 42T chainring on my stunner X the chain was not straight with the center of the cassette. It was aligned with 8th or 9th gear on the cassette,
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
For some reason with the stock 42T chainring on my stunner X the chain was not straight with the center of the cassette. It was aligned with 8th or 9th gear on the cassette,
Well you have to remember that these are diy kits made to fit a wide variety of bikes and rear cassettes.
For me the stock ring plops dead center of a 7sp.
In your case... that's Biktrix for you.
IMO... The more generic the bike, the better it lines up.
 

Ridetoglide

Member
Region
USA
Most of us that have messed with that tool enough to make it do what we want have found it's INCREDIBLY accurate. Well respected by all, and very worthwhile when trying to answer about any question that has to do with e-bike performance. Mess with it when you have a chance and get to know it....
It looks like a great tool.... very technical... I had all to do to wrap my head around it.

I discovered ebikes last year... they open up an entire new world for riding. I have had motorcycles and dirt bikes, i am not looking to go too fast. But the mid drive ebike has this amazing torque at low speeds that I feel like can climb anything. Its nice to be able to sit back and enjoy the scenery while the motor does the work and pedal to add effort on the fly when I feel like it.

So when i found out someone made an ebike motor simulator i thought that was cool to be able to calculate efficiency. Unfortunately my Bafang C691 display does not have a watt meter but i can kind of feel what is efficient but is nice to have a program that can illustrate it. This is similar to flying jet aircraft (my profession), efficiency is very import for range (engine power, speed and the right altitude to fly). With the ebike the variables are assist level, proper gear, cadence, speed and pedaling effort..... 5 Variables!!!! Thats more than a jet.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
It looks like a great tool.... very technical... I had all to do to wrap my head around it.

I discovered ebikes last year... they open up an entire new world for riding. I have had motorcycles and dirt bikes, i am not looking to go too fast. But the mid drive ebike has this amazing torque at low speeds that I feel like can climb anything. Its nice to be able to sit back and enjoy the scenery while the motor does the work and pedal to add effort on the fly when I feel like it.

So when i found out someone made an ebike motor simulator i thought that was cool to be able to calculate efficiency. Unfortunately my Bafang C691 display does not have a watt meter but i can kind of feel what is efficient but is nice to have a program that can illustrate it. This is similar to flying jet aircraft (my profession), efficiency is very import for range (engine power, speed and the right altitude to fly). With the ebike the variables are assist level, proper gear, cadence, speed and pedaling effort..... 5 Variables!!!! Thats more than a jet.
If it interest you that much, you may want to upgrade your display.
Me personally, I really like the 860c which is very easy to read in all light conditions and has the buttons detached for placement near the end of the bar.


IMAG0920.jpg

You could also try something like the Eggrider that will datalog... But I find it very difficult to read while riding and the buttons poorly placed. But it was great for some initial setup and troubleshooting.



Screenshot_20210309-163746.jpg
 

Ridetoglide

Member
Region
USA
Well you have to remember that these are diy kits made to fit a wide variety of bikes and rear cassettes.
For me the stock ring plops dead center of a 7sp.
In your case... that's Biktrix for you.
IMO... The more generic the bike, the better it lines up.
Lol.... for the money I paid you think the bike would be perfect. I guess they have a lot of constraints to meet. well i do enjoy modding it. The Lekkie chainring was a nice addition. The Stunner X is a bit of an enigma. Its a modern mountain bike with a girls frame and cruiser handlebars so the high performance seat and the Lekkie small chainring definitely gave it a more sporting look.
 

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Ridetoglide

Member
Region
USA
If it interest you that much, you may want to upgrade your display.
Me personally, I really like the 860c which is very easy to read in all light conditions and has the buttons detached for placement near the end of the bar.


View attachment 88694

You could also try something like the Eggrider that will datalog... But I find it very difficult to read while riding and the buttons poorly placed. But it was great for some initial setup and troubleshooting.



View attachment 88693
I would like to upgrade my display but is there a way to input the bike's current millage into the new display? I would like the display to read the actual mile of the bike.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I would like to upgrade my display but is there a way to input the bike's current millage into the new display? I would like the display to read the actual mile of the bike.
On the 860c and similar... I think not.
I haven't looked into the eggrider enough as I couldn't wait to put the 860c back.
That said my Odometer is about 200 miles off