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Bafang 750W 135mm front for fatbike

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    Bafang 750W 135mm front for fatbike

    This front hub motor from LunaCycle. Can anyone clarify the characteristics of the motor? What RPM does this motor have? How many spokes are there? How many poles (magnets) at the motor?
    https://lunacycle.com/48-52v-750w-ge...r-front-wheel/
    Attached Files

    #2
    All I can tell you is 36 spokes. I have two, one of which has about 3000 miles on it since March of 2017..

    Comment


      #3
      Originally posted by MoneyPit View Post
      All I can tell you is 36 spokes. I have two, one of which has about 3000 miles on it since March of 2017..
      You have only front motor on your bike? You don't have rear analog of this motor (190mm QR)? And what standart of spokes do you have on front motor? 13G or 12G?

      Comment


        #4
        Originally posted by prof.power View Post

        You have only front motor on your bike? You don't have rear analog of this motor (190mm QR)? And what standart of spokes do you have on front motor? 13G or 12G?
        No I have a front Bafang 750 and rear Bafang 750 on my daily driver (2WD), and I am building another with a front 750 and a BBSHD for the rear (also 2WD).

        The rear is a 190 but it is not QR it is bolted axle. this motor cannot be QR because the cable runs thru axle.

        For both wheel builds I used DT Swiss Champion spokes with 14mm brass nipples, The daily driver is built into an Origin8 DAT-Pro 80 (aka Weinmann DHL80) and the new one is a Weinmann DHL-101 (aka O8 Dat-Pro-100), both are Presta-valved.

        Comment


          #5
          Originally posted by MoneyPit View Post
          For both wheel builds I used DT Swiss Champion spokes with 14mm brass nipples
          I meant the spokes of what thickness you used? 14G (2.00 mm), 13G (2.34 mm) or 12G (2.75 mm)? What is the diameter of the holes for the spokes in the motor? That is, if 12G needles get into these holes, then it seems like you can use 13G without special washers. And if you want to collect on 14G, you will need these washers, so that the spokes do not hang out in the seats.

          In the description on AliExpress to these 750W motors there is a setting of 12G spokes. The usual Bafang 500W motors are 12G and 13G.
          Last edited by prof.power; 01-10-2018, 07:10 PM.

          Comment


            #6
            Sorry my bad. I used the 2.0 Champions. You don't need washers. However, they do set deeply. Due to the thickness of the ears on the motor, they don't hang out. I have put 3000 street miles on them with a few serious collisions, including a 10 mph head on into and up a curb under dual throttle (in hindsight I should not have done that). The wheels remain perfectly true with no spokes having any issues. All remain tight, no breaks etc. I was skeptical but my wheelbuilder is well experienced (I can only make a wheel worse if I touch it... only thing I can't work on by and large on a bike) and his take was the Champions are perfectly strong for the application.

            For my current build I had a hard time arguing with that success. With that said the deep seating of the spokes gave me the creeps and we're doing washers with this one.

            On other wheels, built overseas from the U.S., I have used Sapim Strong spokes and if they were more common in the U.S. -- just about every local bike shop has DT's somewhere in the building or readily available - those would be my go-to for an ebike application. Used them with my Cyclone'd Stumpjumper with DM24's. The wheels were amazing.

            Comment


              #7
              Originally posted by MoneyPit View Post
              Sorry my bad. I used the 2.0 Champions. You don't need washers. However, they do set deeply. Due to the thickness of the ears on the motor, they don't hang out. I have put 3000 street miles on them with a few serious collisions, including a 10 mph head on into and up a curb under dual throttle (in hindsight I should not have done that). The wheels remain perfectly true with no spokes having any issues. All remain tight, no breaks etc. I was skeptical but my wheelbuilder is well experienced (I can only make a wheel worse if I touch it... only thing I can't work on by and large on a bike) and his take was the Champions are perfectly strong for the application.

              For my current build I had a hard time arguing with that success. With that said the deep seating of the spokes gave me the creeps and we're doing washers with this one.

              On other wheels, built overseas from the U.S., I have used Sapim Strong spokes and if they were more common in the U.S. -- just about every local bike shop has DT's somewhere in the building or readily available - those would be my go-to for an ebike application. Used them with my Cyclone'd Stumpjumper with DM24's. The wheels were amazing.
              Diameter of the motor axis is 12 mm? Cutting for installation in dropouts - 10 mm?

              Comment


                #8
                Cutting the dropouts can result in loss of integrity of the dropout if there isn't enough meat on them. On my first bike, on my first set of forks I squared off the round of the top of the dropout and this allowed the thing to seat just a bit higher - the inward curve of the top of the dropout left a bit of usable dead space that squaring them off allowed to be used. This was enough to seat the 12mm axle fully in the dropout.

                After a while I replaced that fork with a stronger one and on those dropouts, rather than squaring it I just used a rotary tool to take the paint down to bare metal. Here again there was just a bit of dead space and utilizing that gave me a good connection. On that bike, whose axle is pictured both sides below, I installed two torque arms plus I upgraded all of the nuts and hardware - did not use the Bafang shouldered nuts with serrated bottoms, and instead used a large flat washer with a serrated ring washer underneath the Grade 8 M12 replacement nut. Using a normal nut gained me back some threads, as did the use of the serrated ring washer. Since I added some very fat torque arms, net result was flush, full thread engagement.

                The two images below are links to much larger versions. Open them up in a new window if you want the gigantic version, where you can get a close look at the seating.





                These ring washers are outstanding for locking together a nut and washer subject to vibration. And they take up almost nothing in terms of threads. Invisible as they are smaller than the nut. the one in this picture is about twice as thick as those found in local hardware stores.

                For my most recent build, I am doing things very differently, and I may not be done. First, that fork - an Origin8 Scout fork - is aluminum. Livable as this motor is not powerful enough to break it. But still bears scrutiny. That fork does have deep indentations to seat the axle nuts and I am using ring washers again, in two different sizes, to overcome this under the nut... this time as seats to raise the contact point of the nut. Two layers with one larger than the M12 and fitting perfectly and filling the depression, and the second being an M12. There is enough meat around the dropouts that I still have full contact. Coupled to two torque arms again, I should be be fine.

                However I have a 150mm Chromoly Motobecane Lurch fork on the way that I am going to play with and see if I can make it work. I am thinking the two torque arms, which are 7mm in depth each, give me 14 of the 15mm of extrra spacing those 150mm forks introduce. I am going to try and put them inside the fork blades rather than outside, then bolt them up as needed. I have a number of different torque arm parts on hand so - like the right arm you see above, where I decided to use a second anchoring point for the sake of overkill - I may need to get a little creative to make it work. But thats part of the fun of the project.
                Last edited by MoneyPit; 01-12-2018, 11:52 AM.

                Comment


                  #9
                  prof.power I just realized those pics above give you an excellent look at how the DT Champion 2.0's seat in the hub.

                  Comment


                    #10
                    Originally posted by MoneyPit View Post
                    prof.power I just realized those pics above give you an excellent look at how the DT Champion 2.0's seat in the hub.
                    Is the angle of the needle in the rim optimal? Looking at your spokes, you can say that it is good, but I suspect that the spokes sit in the holes of the motor not as they should. Still, I think I'll use at least 13G spokes. Maybe even 12G, but for this it will be necessary to reamer the holes in the rim.
                    I plan to use a battery with a rated voltage of 72V and a nominal and maximum current of 25A. The controller is planned for 6Fet 25A. Voltage engine will digest without problems, but about the current is not yet clear.
                    What are the voltages and currents you use on the front and rear motors of this bicycle?

                    Comment


                      #11
                      The angle is not optimal, but it is not bad, either. Thats why you use 16mm nipples made of brass, to help counteract that issue. You are correct that if you try to use 12G you will have to drill out the rim as the nipples will be larger than the holes. Another possible option is Sapim polyax nipples.

                      I was concerned too but my wheelbuilder assured me the DTs with long brass nipples were plenty strong as was the double wall rim. Its hard to argue when there has been no loss of perfect true after more than 4800km from March to December.

                      52v nominal (58.8 peak). 35a peak. About 2200w per motor on a full charge so on the once-per-month balance charge or long-distance trip days, I am running 4400 watts, and I do peg the throttles as we have bike lanes on 50 mph superarterials here where I have no issues cruising on PAS at about 54 kmh. With a smaller person and no loaded panniers I'd be faster. The front wheel will spin if you don't apply the throttle carefully. It will still lose a bit of traction at the highest PAS level.

                      Since this pic was taken I have mounted that same rack on the front. 60T chainwheel lets me pedal up to that 54kmh speed.

                      Last edited by MoneyPit; 01-12-2018, 02:45 PM.

                      Comment


                        #12
                        Originally posted by MoneyPit View Post
                        The angle is not optimal, but it is not bad, either. Thats why you use 16mm nipples made of brass, to help counteract that issue. You are correct that if you try to use 12G you will have to drill out the rim as the nipples will be larger than the holes. Another possible option is Sapim polyax nipples.

                        I was concerned too but my wheelbuilder assured me the DTs with long brass nipples were plenty strong as was the double wall rim. Its hard to argue when there has been no loss of perfect true after more than 4800km from March to December.

                        52v nominal (58.8 peak). 35a peak. About 2200w per motor on a full charge so on the once-per-month balance charge or long-distance trip days, I am running 4400 watts, and I do peg the throttles as we have bike lanes on 50 mph superarterials here where I have no issues cruising on PAS at about 54 kmh. With a smaller person and no loaded panniers I'd be faster. The front wheel will spin if you don't apply the throttle carefully. It will still lose a bit of traction at the highest PAS level.

                        Since this pic was taken I have mounted that same rack on the front. 60T chainwheel lets me pedal up to that 54kmh speed.

                        Do you use a double rim on your bike? Are your wheels with tubers or tubeless?
                        As far as I know, there are no perforations in the double rims and the camera can rotate in the tire. And the weaker the pressure, the more the camera turns.
                        I'm going to use a single-walled rim with perforations to avoid turning the cameras at low pressures.
                        Such a design is optimal, do you think?
                        Of course, if you use tubeless technology, you do not have such problems and you can use a double-walled rim.
                        And of course, I liked the design of the dropout amplifiers on the front fork.
                        I'm still going to use a simpler design (plate thickness 3 mm):
                        Click image for larger version

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                        Hmm, I see you're using Cane Creek Thudbuster ST Seatpost. I also thought about it, but thought about the version of LT (75 mm stroke). Do you like this solution? Can you describe your impressions of this transition? When I bought a fatbike, I liked that the low pressure of its tires can eat the smallest irregularities. While on narrow tires (up to 2.5 ") and high pressure (from 2 bar) such small irregularities are very strongly felt, even on full suspension, but the average and large irregularities are still felt on the fetbike and still have to stand up, especially on the narrow 27.2 mm seat post.

                        Comment


                          #13
                          Yes those are double-wall Weinmann DHL80's, but branded as Origin8 DAT-Pro-80's. Same rim no matter which one you buy. You will only see cutout rims (perforations) on single-wall rims. The double wall rims weigh more but I value strength over weight reduction on an ebike that gets a daily beating.

                          I think your translator is mistaking the word 'camera' for something else. Your text doesn't make any sense as-is. But I *think* you are referring to the inner tube? The valve stem? Regardless, nothing rotates within the tire. Double-wall rims have been around a lot longer than perforated ones with zero issues.

                          For sure, the valve stems do not rotate at all because they are Presta valves and you screw a presta valve down to the rim on installation. It can't move and never does.

                          In my opinion, a single-wall rim with cutouts is only optimal if you can benefit from it. If you are riding a fat bike like it was originally intended - slow, with human power only, across unimproved terrain (or a trail) then the weight reduction you get from the cutouts and the single wall construction makes sense. If you are riding a fast ebike on the streets then I think they make no sense at all when stacked up against a double-wall rim that is inherently stronger and you have a motor that wipes out the weight disadvantage.

                          'dropout amplifiers' translate to 'torque arms' in English :-) My drive-side torque arm is a mishmash of different parts. I decided I had the extra parts so what the heck lets use them to really lock this thing down. Its definitely overkill, especially considering I have a second torque arm on the other side.

                          I have destroyed a steel fork (spread the dropouts) with one of these motors when I had no cutouts and went to 100% throttle from a stop. If I were you I would (a) use two torque arms and (b) use a better torque arm. 3mm thickness is not much. It won't bend but you want more meat gripping on your axle. With that said, I have a couple of these and they are very well made, that seller is in your country and he's a straight-up guy. He sells the same design you show above albeit in 4mm thickness. I very much recommend you go with the thicker design he sells, and then maybe use the link below and use that one for the non-drive side to attach to the brake mount (assuming you have IS mounts on your fork and not posts).

                          https://www.ebay.com/itm/Universal-T...YAAOSwgY9Xdjpy

                          I have tried to use that design and the thicker Grin Technology original version and could not make it fit. the angle of the axle flats was wrong.
                          I prefer these 5mm arms and have two to use on my current project:

                          https://www.ebay.com/itm/Torque-Arm-...53.m2749.l2649

                          If you want to REALLY get serious, Grin Technologies originated these designs and their original versions are here. Thicknesses are 6.3mm.

                          http://www.ebikes.ca/shop/electric-b...rque-arms.html

                          I prefer the ST version of the Thudbuster. If you are riding offroad perhaps you need the extra travel. Personal preference I think. On impressions: You don't know its there. Your angle to the pedals doesn't change enough to notice. What I did notice was my back pain immediately and permanently went away the day I installed it, so I have put them on by other RWD single-motor fat cargo bike and this new 2WD bike gets one as well.

                          Comment


                            #14
                            Yes, there are difficulties in translation. The terms are especially difficult to translate. So I try to write simple sentences. They are easy to translate and understand.

                            5 or 6.5 mm thickness of torque arms? A lot of thickness. It seems to me that this will be enough even for powerful direct drives. Unfortunately, I have already ordered the ones whose images I applied. I'll try to travel with them.

                            Under the word "camera" I meant "inner tube". I still do not understand. Do you use internal tubes? Or your wheels are tubeless?

                            Comment


                              #15
                              I use inner tubes. They have Presta valves. Also known as French valves. You see them mostly on road bikes and higher end mountain bikes. Presta valves are locked down onto the rim and cannot move.



                              That screw holding them down also means if you have really low pressure the valve doesn't fall into the tube when you press an air chuck onto it.

                              Typically, tubeless setups use Prestas also.

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