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Help with BBS02

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    Help with BBS02

    After trying a Davinci e assist wheel chair adaptation at Interbike a few years ago ( I knew that one was in the future for my son who landed himself in a wheel chair 6 years ago. It took awhile to get it together to get one but finally did. The one I tried had a DD hub motor but the one we ended up with is set up with a BBS02. In retrospect as much as I think Mid Drive is a good idea I am thinking that for this purpose a hub motor might be a better way to go but it is what we have and I am sure that it will work out well enough in the end.

    It has not been an easy plug and play system but I have had the skills to get the setup fit to his chair up to this point. Where I am looking for help is now that he is finally able to get out on it and there seems to be some issues with the drive unit. The drive is hooked to an 8spd Shimano Nexus IGH front wheel btw.

    As my son is a Quadriplegic his arm strength is not great but he does have a stationary arm bike that he uses for rehab so I know he has enough range of motion to get the cranks around and enough strength to be able to get it going if it is working as I think it should. The problem is that it is taking too much effort to get the PAS to kick in from a standing start. Is there any way to make this better? Not so bad on flat ground but any type of incline makes it hard for him to get going on his own. They made the throttle accessible to him if he takes a hand out of one of the tri pins but it seems to only want to work once in awhile also which doesn't seem right.

    Once underway he tops out at around 6mph before the system hits a limiter that he can feel and interrupts the flow of his cranking. I would think that even an EU spec model would allow him to go faster than that?

    We are going to do some more testing this weekend with it, his condition doesn't allow him much time outside in cool weather, but with warmer weather on its way I am hoping to get it straightened out so that he can use it to the best of its ability. He is pretty pumped up about the prospect of being able to rip around on it!

    Thanks in advance,

    Bob in the PDX

    have you looked into reprogramming it. Karl at has written lots about the BBS line and has even put together a few guides to get better results - a-hackers-guide-to-programming-the-bbs02

    program cable if needed can be found here


      Thanks for the come back Madman. I did some reading up on that but having to have a windows computer in a Mac family is kind of a problem. If that is the only way to go I guess we can work out something.


        I had an old copy of XP, and installed it on MAC using a virtual program that run windoze stuff. All just for my BBS free an works well. When I'm on the Mac I can look up the name, or send me a message @ Luna support. I work it from my Mac. Old windoze disks are usually easy to find. Just don't use their browser.


          Thanks Louis, I will look in to that method. Guess I had better get one of the cables on the way regardless.


            I ended up getting in touch with Paul at EM3ev and he sent me this info which I found to be the information I needed. Maybe it will help others to understand how the BBS02 system works most effectively? As it turns out for our needs the programming adjustments can be done with the 5 button pad which are outlined in the stock literature provided with the unit or available online.

            BBS Instructions and Info

            BBS02 kits are programmed with 100% throttle no matter the PAS level selected (including 0 setting, which is a throttle only setting). Speed limit is set by the display and can be adjusted to a max of 40km/h for the C963 display, 50km/h for the C961 Display and 99km/h for the C965 display (adjustable from to 25km/h, up to the max level. It is not possible to completely remove the speed limit. The number of PAS assist levels and the wheel size are also set from the display and can be set to between 3 and 10 (0-9) PAS levels. The C965 and C961 allow up to 10 assist levels (0-9), but the C963 is limited to just 3 level (1-3).

            The standard BBS01/02 has a BB (Bottom Bracket) section with a diameter of 33.5mm and is intended to replace a BB of 68mm in length. These motors can also be installed into a 73mm wide BB, with some small modifications. Be aware, there is a limited amount of space between the motor housing and the BB section (~13mm), as shown below. So if the frame has a very thick Bottom Bracket Tube, or if the bike has an unusual design, then the motor cannot fit. For the 100mm BBSHD or for a modified BBS02, intended to 100mm BB, then in both cases, the BB section of the motor is still 33.5mm diameter, but the BB section is longer, to match the 100mm wide BB found in Fat Bikes.

            In our experience, the PAS function of the BBS02 kits work well if they are used in a certain way. We suggest you forget about the PAS level as being an assist level. It is better to consider the setting as a way to adjust the pedalling cadence (speed at which you turn the pedals). Just because it is set to the max setting, does not mean it will pull more power, just because you set it to the minimum setting, does not mean it will necessarily pull less power from the battery (although it will of course tend to use more power and go faster in a higher PAS setting, than a low setting). The PAS system on the BBS02 kit works like a switch, it does not increase assistance as you pedal faster, it simply applies assist at a certain power and motor speed when it detects the pedals are turning, the speed and max power provided for each PAS setting are programmed into the controller and cannot be changed by the end user. The power provided by the motor when used in PAS mode will increase, if it detects the load has increased (such as changing to a higher gear or approaching a hill), then reduce again as the load goes back to a constant level. As previously stated, the motor speed does not significantly increase or decrease if you pedal faster or slower, and that is why we suggest the PAS level is used to control the pedalling cadence (motor speed).

            If you are pedalling hard and can feel you are applying some effort, the motor will automatically do less of the work and the cyclist, will do more of the work, meaning you will travel further on a charge. It is simple, you control how much effort you want to apply, by either pedalling harder, or with less power, so therefore letting the motor do more of the work. Use your bikes gears properly, as you would without motor assist. Select the PAS level so the motor turns at the speed you like to pedal, apply as much or as little effort as you want, use your bikes gear system to fix the speed at which you want to travel on the road, do not control road speeds by just the assist level, use the gears too. Don’t pick an overly high gear on the bike, then pick a low assist level and think you are using less power. You will be operating more efficiently, if you choose an appropriate gear, to allow the motor to spin at a moderate to fast speed (this is especially true on hills). Just because the motor is strong and can pull the highest gear, does not mean you are using the system in the best way. Making the motor work hard at low motor speeds (speed at which the motor turns or pedalling cadence) risks overheating the motor and blowing the controller, and ultimately, motor failure. The kit works better if the motor is spinning at a reasonably high speed, not labouring at a low rpm in a high gear. Trying to use a high gear whilst going up a steep hill is a great way to blow the controller and overheat the motor. If the bikes gearing is too high to allow the motor to spin at a reasonable speed, it is suggested you change to a smaller chainwheel, or change the freewheel/cassette, so that the lowest gears are low enough to allow the motor to spin at a moderately high rpm whilst travelling up hills.

            If you are travelling at high speeds, you will use more power than if you keep speeds lower (as speeds get significantly over 20mph/32kmh, the power requirements go up very significantly). Use a combination of the bikes gear system and the PAS level, to pick a suitable road speed (a moderate speed, such as 25-32km/h is efficient, travelling much faster will reduce range significantly) and pedalling effort, so you are making the most efficient use of the motor and human effort combined, and that will help you get the best range from your battery. Alternatively, you can just use the throttle and let the motor do the work, but be aware that as speeds increase, the power required to cover a given distance also increases and as speeds get to 25mph (40km/h) plus, the power requirements increase massively. When using throttle only, to travel up steep hills, it is even more important than ever, to pick an appropriate gear, so the motor is turning at a reasonable speed, labouring up steep hills in a high gear is very likely to eventually damage the motor. The bottom line is this; the bike has gears to help the cyclist make the best use of the available power. Just because you have a strong motor, does not mean you shouldn’t still use the gears to make the best and most efficient use of the available power.


              I don't count myself as stupid but I feel it when I try and read detailed explanations on how the BBSxx PAS system works and the best way to make it run for my riding. I think I could do with a diagram or video explainer.

              I am not sure if I am correct, and in all honesty I feel my way but I think what it means is just ride your bike as normal. Use your gears as normal. The PAS needs you to tell it how much effort to offer by selecting the PAS level. It'll work at that level when you pedal but will start to reduce its effort if you put in above a certain level of input. The major thing to retrain your brain is to resist putting in lots of effort when the going gets tough.

              I like the way it works versus torque sensing. Both have plus/minuses. On a torque sensing motor if you want more assist then you have to put in more effort. But sometimes you need more assist in a technical section and don't/can't put in the required effort or conversely you don't want more power to accompany a natural hard push on the pedals.

              The Bafang throttle is also a brilliant get out of jail card when the going gets tough. The complete bike torque sensing models can't legally have a throttle in the UK.


              • calfee20
                calfee20 commented
                Editing a comment
                I just finished a DD hub bike. The first ride was throttle only. It was a small electric motorcycle and a lot of fun. Then I set up a 1 power level PAS and while OK I need more levels. I am waiting for a up down level switch from Grin now.

                I like to think of PAS as foot operated throttle but your input will increase the performance of the bike and give you some exercise. The PAS in a BBSXX is superior to a Cycle analyst because there is some variability to it. One setting will vary by a couple of hundred watts depending on speed and cadence. The Cycle Analyst though gives you what it is programed for, say 500 watts, pedal and bang 500 watts.