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Dual electric hub motors?

Old 11-06-20, 07:47 AM
  #26  
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Interesting set up. I dont think my brain could handle two different throttles.
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Old 11-06-20, 10:21 AM
  #27  
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Thanks Bluesfrog but it actually hasnít happened yet. Have everything for the front hub, mounted all the controls on the left side handlebar but still awaiting a lot more parts/tools for the rear cassette hub motor and decided not to test out the bike before both were ready to go. Also had to order a set of SS braces to lower the 6-gallon battery buckets for clearance of the J-hooks over the pannier rails under the RANS seat. Not to mention, working on a new trailer integrated into a 48Q matching blue Igloo cooler. Wonít go into all the details here, will save for a new thread regarding installation on a LWB recumbent cargo bike. Anyway, here are some progress pics (which should also make clear why I need a e-assist )




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Old 11-06-20, 10:38 AM
  #28  
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Originally Posted by skookum View Post
Interesting set up. I dont think my brain could handle two different throttles.
Dunno whether mine can either.

Actually though itís easy to mirror hand motion. E.g.: whether you are right or left handed, while writing your signature on a white board with your favored hand you could simultaneously write it either forward or backward with your opposing hand quite easily. Learned that in Psych 101!

Anyway, might have to enter two different assist levels to compensate for the unequal weight balance, will find out once the whole system is in place.
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Old 11-09-20, 01:39 AM
  #29  
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Originally Posted by andychrist View Post
Dunno whether mine can either.

Actually though itís easy to mirror hand motion. E.g.: whether you are right or left handed, while writing your signature on a white board with your favored hand you could simultaneously write it either forward or backward with your opposing hand quite easily. Learned that in Psych 101!

Anyway, might have to enter two different assist levels to compensate for the unequal weight balance, will find out once the whole system is in place.
There is the possibility of controlling one motor from the cranks (PAS or torque sense) and the other from the throttle. OR the two throttles can be 1/2 size and ganged together with a sleeve of some kind so they rotate together. I am better than most at using both hands together and separately being a trained concert organist and I wouldn't want to try a throttle in each hand. You'll probably end up just not using one or the other and I know what those motors weigh. Lugging one around for no good reason just doesn't make sense.
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Old 11-09-20, 02:14 AM
  #30  
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Originally Posted by Leisesturm View Post
There is the possibility of controlling one motor from the cranks (PAS or torque sense) and the other from the throttle. OR the two throttles can be 1/2 size and ganged together with a sleeve of some kind so they rotate together. I am better than most at using both hands together and separately being a trained concert organist and I wouldn't want to try a throttle in each hand. You'll probably end up just not using one or the other and I know what those motors weigh. Lugging one around for no good reason just doesn't make sense.
Well as I mentioned previously, the press-fit bottom bracket on my bike is incompatible with any PAS sensor that Bafang offers. Nor would I want to install anything like that at all since am intending only to use the assist on hills; would be a PITA having to turn the assist on and off throughout a ride by way of a button control. Absolutely no way to gang the two twists together, theyíre angled almost 90ļ from each other on the RANS 3-way chopper bars (and Iíd have no intention of doing so to begin with.) Not such a big deal rotating both [half] twists simultaneously, as they come in left and right iterations so operate symmetrically ó itís actually easier than just turning one while leaving the other hand in a fixed position (kinda like adjusting grips on the fly, youíd want them to mirror each other.) Only issue might be, as the weight on the Stratus is so heavily biased toward the rear, will likely have to adjust the two assist levels differently to find the sweet spot where the wheels pull evenly while I pedal. Anticipating a lot of experimentation!

P850C display I ordered for the right side handle bar/rear hub motor is at the PO and should be delivered this afternoon, so am hoping to complete the setup by evening. Will post results, if I survive.
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Old 11-20-20, 05:55 PM
  #31  
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Encountered a lot of incompatibilities/problems with the RANS frame, had to file and burr away sections of the dropouts to get the rear axle to fit because they were askew (and of course took time to procure all the right tools for the job.) Impossible to adjust the TRP Spyke interior disc brake pistons with the wheels on, as the hub motor blocks access to the 3mm opening. Not to mention USPS sent a couple of my orders astray, still havenít received the last two battery cable extensions.

Anyway, finally got the two Bafang kits hooked up best as I could late this afternoon and nothing exploded when I turned the power buttons on.



Chose the 500C display for the left/front as thatís how its buttons work, and a P850C for the right/rear as it has a remote switch thatís basically handed-agnostic (mounted its display on the center bar.)



Installed a couple Grin Tech TorqArms_V2 on the front fork and a single V4 in the rear. Would have gone with two TorqArms there as well but unfortunately the RD cabling got in the way, grr. As it was, had to remove the crappy Hebie Fox M Adjustable Kickstand, which probably couldnít support the weight of an eBike anyway.



Latest style of rear hub motor has the power cable passing out the drive side axle so doesnít interfere with a trailer hitch.

Still have to figure out programming the controllers through the two different displays, but even without configuration in assist level 1 a twist of the throttle turns the wheels with incredible torque. Darkness fell before I could take Blutus out for a spin (donít mind riding at night but not when I anticipate having to make adjustments.) Hoping for the first full fledged run tomorrow.

Last edited by andychrist; 11-20-20 at 06:11 PM.
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Old 11-21-20, 07:42 AM
  #32  
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Very impressive work.
Be careful riding that power thing.
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Old 11-25-20, 06:56 PM
  #33  
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Update

Well last Saturday’s first trial run was an unmitigated disaster, thanks to the crappy host bike and its incompetent mechanic (that would be me.) Steerer quill stem came loose while riding down the hill from my house; by the time I’d gathered the right tools and and tightened it back up the sun had set. Then ended up having to walk the bike most of the way back home in the dark because the front rotor had started scraping against the inside of the fork — which it hadn’t done on the stand, was my weight that put it over the edge

So added a spacer in the disc side, which kept the rotor from scraping but caused the six motor bolts on the power side to contact the fork, D’oh! Luckily had spare U-shaped lawyer lip inserts left over from the Grin Tech TorqArms that I hadn’t had to use (since Bafang supplied more specifically tailored hardware in their kit); stuck one in as a spacer there so that the motor cable could exit the axle without getting pinched. Also faced the axles’ exterior steel washers with rubber units both front and rear, makes it easier to torque the end nuts tightly without stripping the threads.

Remaining fly in the ointment, host bike’s drive train components still not all compatible, will have to measure the chain line and figure out how long a spindle will be needed for a square taper BB to replace the current splined unit in order to swap out the FSA Vero 50/39/30 crankset for something a little more mountainy. Because only clamp-on bottom pull FD I could find that works with the SRAM Rocket triggers was an SLX which doesn’t really handle outer chainrings over 44T. Temporarily jerry-rigged it to shift the Vero, but it’s not even close to perfect, can hear the chain grating inside the cage when pedaling no matter how I adjust the cable and everything, grr.

Long story longer, finally got out for a revised test ride late this afternoon and aside from the minor drive train issue, bike handled superbly. Dual throttles no problem at all, easily assists pedaling in any gear with both hubs only on level 1. Have set nominal cut-off speed to 12m/20kph and reaches 11.8mph in actuality. Quieter than the drive train. Of course, do notice the additional weight (~50 pounds more, whole setup probably around 100) but is more stable in a wind and coasts down hill even faster than before. Momentum it builds creates the illusion the bike is still being powered after the throttles are released.

Had been sorta skeptical myself prior to installation regarding whether dual drive would offer more of a benefit than a hindrance, and am pleased to report my doubts were unfounded. The two motors combine harmoniously, don’t feel them fighting each other no matter how I vary the twin throttles. And dual drive really helps to make it over slippery/loose surfaces. Rounding the beach tree middle of my back yard or scaling the hill up to the kitchen landing, powering a single hub either front or rear and the wheel would occasionally spin out; with both engaged the bike just zipped along. Best of all, was finally able to conquer my property’s steep gravel driveway, which curves away from the highway at a perilous angle. Worth the extra price and effort for that convenience alone.

Just managed to squeeze in one lap before it began raining, and upon reaching my back porch the rear wheel began to rub somewhere on the frame similarly to the previous issue with the front fork. Too dark to see where the problem is, but did notice it being off center. Had installed an extra spacer over the cassette so that the chain would have no chance of grazing the stays when on the outer cog; guess it needs to be balanced with a similar or possibly thicker washer inside the disc side. Could also be the misaligned dropouts that I had to saw and grind away to get the squared axle to drop in, resulting in significant lateral play before the nuts are tightened, even with the TorqArm_V4 in place. Anyway, am sure to figure out some kind of fix (even if it means purchasing a whole new frame.)

Happy Thanksgiving everybody!
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Old 11-28-20, 11:55 AM
  #34  
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Update Update Update



Banged the rear wheel back into place, then tightened the snot out of the axle nuts and TorqArms. Now both wheels stay centered in the dropouts.

Went for a 33 mile round trip yesterday, was still fairly mild and windless. Kept the Assist on Level 1 and max speed set to 12mph, which in use actually cut off at 11.6mph. With trailer and DIY Igloo cooler panniers, bike weighs in around 125 pounds. I myself am around 175-180 (fully clothed in autumn attire); schlepped home around 100 pounds of supplies for a total about 400lbs. Bike still handles pretty well for the weight, though steering is not quite as easy as on my unassisted version of the same model recumbent. Think maybe the density of the hubs make them act gyroscopically, which offers stability at the expense of agility. Plus, the twin battery buckets are not particularly aero, so descending over 25mph I can really feel wind resistance shaking the bike, which is pretty unnerving lemme tell you. (Of course I could just make use of the TRP Spyke disc brakes, but what fun would that be?) Also wish the Stratus could accept tires over 1.75, the Schwalbe Marathon Plus mounted now are super grippy (and sluggish) but feel a bit undersized for the Bafangsí and DireWolfsí added heft.

Anyway, made it up the longest and steepest hill on the route at 10.9mph while pedaling like the dickens. Must have shaved a couple hours off my regular excursion time, not sure exactly how much because still havenít taken the trouble to figure out how to reset the tripometers on the two Bafang displays.

Worth noting as well, the half twist throttles were easy to keep fixed in the same position; when fully opened provide an ersatz cruise control. Transition between assist and self-power pretty much unnoticeable, guess the motors kinda fade in and out softly around the cutoff speed. My only difficulty was mental, regarding the interplay between trigger shifters and throttles. Despite not having used grip shifters in years, kept finding myself twisting the throttles rather than plunging the triggers when attempting to shift gears. Fortunately the Bafangs are powerful enough that I can ride in practically any gear combo and still maintain speed, so donít have to shift nearly as frequently as on my unassisted bikes. In any event, am confident Iíll soon get the hang of it all and will be able to run on ďauto pilot.Ē

So at least for my use case, that being a LWB recumbent cargo bike, the dual drive system seems to have paid off. 750-1000W mid drive might have worked as well, or maybe a single, 750/1000W rear hub drive had I found a compatible one before ordering the twin 500W Bafangs. But a mid drive would have demanded the purchase of a strong new wheel set (bought the Stratus used without its wheels and seat for a sizable reduction on price + shipping) plus meant the sacrifice of the beautiful FSA Vero 50/39/30 crankset, which works surprisingly well on an electric conversion. And a single rear drive would have been less effective on wet or loose terrain, while dual drive provides more reliable traction while evening out wear somewhat between front and rear tires.

A bit more work in store, gotta drill holes in the battery buckets through which to route the power cables, which am planning to tidy. Picked up a hole saw bit for that yesterday and have 5í of 12AWG stranded copper wire on order, as well as XP60/90 connectors so as to run the batteries and motor controllers in parallel with a single run along the top tube. Then will take all the excess harness lengths dripping from the chopper bars, wind them into a nice neat coil between the Jagwire minaret (in place of the current Rhinowalk bag there now) and fasten on a small wreath for stealth ó thereís an Xmas tree arbor down the road a pace that just opened for the season. Then wrap the rest of the exposed harnesses and cables with camouflaging blue tinsel, and apply more of the same to the seat bag in back to complete the illusion of holiday festivity. Dunno what Iíll do after New Yearís though, will cross that bridge when I come to it.
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Old 12-04-20, 05:31 PM
  #35  
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Just saw this: https://electrek.co/2020/12/04/super...c-bike-review/



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Old 12-14-20, 06:17 AM
  #36  
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The e bike weighs in at 100 pounds! 400 max load. Need the power to move the tub.

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Old 12-14-20, 09:22 AM
  #37  
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To me,scary in many areas, not the least of which is a 750w motor on a front fork with aluminum lowers. However, interesting.
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