Couple geared front hub questions

[EMGX]

I just got my wife a Biria Easy Boarding Easy 7 bike, she loves it and it is clear that the Dahon Briza that I put a TSDZ2 on will no longer be a regular rider for her. In fact she wants me to remove the mid drive and restore bike to stock so she can easily put it in her small SUV to take to rides with her friends - they only ride slowly on paved flat paths.

Right now she doesn't even want an assist for the Biria but eventually she will for hillier paths than what she has tested the bike on. The Tongsheng won't work on her new bike.

I have a MXUS 36v geared front hub motor that I have taken out of the 26" wheel that it came with and laced it into a 16" wheel to try on a BOB type trailer. That was just messing around so I want to re-lace it into the original 26" wheel again and maybe try a better controller to see if the motor can provide better assist on steep hills than I found it to provide in the past.

I'd like to use WP connectors instead of the standard automotive type connectors that it currently has - anyone do this? Would cut and splice be the best approach or has anyone opened a motor and switched the wire loom completely? If I change the wiring loom to the motor to WP then I can use a KT WP controller and peripherals.

When I removed the motor from the original wheel I didn't realize that it had two different length spokes (7mm difference). I thought the rim was centered between the motor hub flanges but now not sure if the shorter spoke length is used on the left side to pull the wheel toward the disc brake side or if the shorter spoke just alternates with the longer spoke on the same side of the hub (longer for the spoke that laces with its head on the inside surface of the flange, shorter for alternating spoke with its head on the outside of the flange. I've laced a few wheels over the years but don't recall if the alternating spokes are different lengths.

 

[harryS]

Yes, you can splice a 9 pin connector to your motor. Unless your motor opens up easily, I would splice it. The first time I did it, it was quite hard to solder the thicker phase wires together and make a bundle that still fit thru a 12mm axle nut. Then I started using the metal forms out of smaller crimp connectors. The Hall sensor wires are easily soldered. I try to put the join in an area of the cable that doesn't get moved. That is shrink wrap in the 2nd picture, not the heavy crimp plastic,

 

[EMGX]

Yes, you can splice a 9 pin connector to your motor. Unless your motor opens up easily, I would splice it. The first time I did it, it was quite hard to solder the thicker phase wires together and make a bundle that still fit thru a 12mm axle nut. Then I started using the metal forms out of smaller crimp connectors. The Hall sensor wires are easily soldered. I try to put the join in an area of the cable that doesn't get moved. That is shrink wrap in the 2nd picture, not the heavy crimp plastic,

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Thanks, super helpful.

 

[harryS]

A 7mm difference in spoke length is a lot more than what I've seen. I've used the GRIN spoke calculator about a half dozen times and never saw much more than 3-4mm. Hub motors are dished though, so the rim is centered in the bike frame. That means the spokes on a rear drive are all longer on the side with the brake rotor.

 

[EMGX]

A 7mm difference in spoke length is a lot more than what I've seen. I've used the GRIN spoke calculator about a half dozen times and never saw much more than 3-4mm. Hub motors are dished though, so the rim is centered in the bike frame. That means the spokes on a rear drive are all longer on the side with the brake rotor.

I should have paid more attention to the spokes when I took the hub motor out. They are 7mm different lengths, it is a front hub motor. I'm sure I'll get it back together OK, eventually but would like to avoid having to lace the hub in twice. Until I got the new bike for my wife I didn't think that I would ever use the motor in the 26 wheel again, but things changed. I'm interested in seeing how it performs with the 11a-22a KT controller. The original MXUS motor kit was pretty minimal with an unmarked controller, throttle, PAS, no display. The kit listed 250w but the hub itself is marked 36v with no marking regarding what wattage it was wound for. Maybe it was controller limited to meet European standards.

 

[harryS]

Well, maybe one side of the motor has a smaller flange. You can also run the numbers thru Grin's spoke calculator,

 

[EMGX]

The flanges are both the same diameter. I'm pretty sure that the shorter spokes go on the disc brake side of the hub to center the rim between the dropouts but I'll find out when I lace the hub back into the rim today or within the next few days. On a couple other bikes that I tried this motor on in the somewhat distant past the right side of the motor face rubbed on the fork just above the dropout, thankfully no such problem on this bike. Received the new 11a/22a KT controller yesterday along with a 9 pin motor wire and 1 to 4 controller to peripherals wire. The controller is over an inch longer than the 11a/22a KT controller that came with my geared rear hub motor kit so maybe it is 9 vs 6 MOSFET? Not sure what the practical difference would be. I have a spare KT display/button pad as well as an extra stick on brake-motor inhibitor as replacements sent for my rear hub kit which had a defective display mount that doesn't affect performance and a nonfunctional brake inhibitor that the seller replaced with a package of two that work. So if it works well I'll only have an extra $60 into this bike to make it into a front hub assist bike. Biria price for similar but in some ways lesser equipped bike is $2,250. I'll wire it so I can quickly remove the motor and battery for when my wife wants to ride it as a lighter bike without assist.

 

[harryS]

3.75" or 95mm for my various 10A/20A controllers.

I've got a 25A model that is an inch longer, and it is 9 FET. After having it for over a year, I installed it on my ride-with-my-wife bike, and had to cut the current back to 20A, because I couldn't ride it slow enough to ride with my wife. I'll have to take it off and put it to a better use on a different bike someday.

By the way, if you ever want to splice a female 9 pin socket from a waterproof cable to a controller, that is best done making all the splices inside the box. Then you can just twist the wires, solder, and not worry about strain relief or being compact,

 

[EMGX]

The thing that puzzles me about the KT controllers is that they are both rated the same 11/22a but one is longer and heavier than the other. If it seems to supply too much current and makes the bike difficult for her to ride I can switch over to the smaller controller from the rear geared kit. The main reason that I wanted to switch the MXUS motor to WP connector is my two controllers have WP connectors to be compatible with the crank sensor and display/brake inhibitor/throttle wire WP connectors. As long as it works for her I think that I have finally found the right bike for my wife to keep her riding as long as possible.

 

[EMGX]

You can also run the numbers thru Grin's spoke calculator,

I re-laced the hub back into the original 26" wheel using the shorter spokes on the disc brake side of the hub. I still need to true and center the rim better but it looks like the long spokes are a bit longer than necessary and the short spokes are a bit shorter than optimal. I didn't pay much attention when I took it apart because I didn't think I would ever use it again with the 26" rim, paying for that now. I might get to doing some final adjustments later today or tomorrow.

The GRIN calculator isn't any use for the MXUS fx07 hub. I used it when I put the hub in a 16" rim. It states that the center of the hub is centered on the axle between the dropouts and calculates spoke lengths as being the same on each hub flange. I went with their calculated spoke lengths for the 16" wheel because it was simpler to order one length spoke and I was just experimenting with it - as expected the rim was displaced away from the disc brake side of the hub, because the xf07 isn't centered as Grin assumes. The center between the flanges is displaced about 1/2" farther away from the disc brake attachment side.

I'm only working on this project a little here and there but want to finish it by Friday when a Tongsheng TSDZ2 48v 750w mid drive motor is scheduled for delivery - putting it in a Schwinn hyrid.

 

[harryS]

Yoy have to enter the axle offset in the Calculator, The spoke lengths will change, and you will see the rim move in the provided image.

 

[EMGX]

Yoy have to enter the axle offset in the Calculator, The spoke lengths will change, and you will see the rim move in the provided image.

Except grin has a brand and model specific drop down. The fx07 is incorrectly listed as zero offset and does the calculation based on that, it can be overridden but no worries, I have it relaced and true now. Tomorrow maybe finish it up.

 

[harryS]

None of my motors are in Grin's database except the Bafang G60. Maybe if I bought Grins motors, but I'm too cheap,

 

[EMGX]

None of my motors are in Grin's database except the Bafang G60. Maybe if I bought Grins motors, but I'm too cheap,

This kit was definitely cheap when I bought it several years ago. If I recall correctly it was under $150 for a basic setup with the MXUS motor laced into the rim, KT controller, throttle and crank sensor. The original controller doesn't have a low amperage listed, only that it is 15a peak (I thought it was an unmarked controller but was wrong about that). Hoping that the new 11-22a controller will give it more power to help on the hills. Will see.

 

[EMGX]

Yes, you can splice a 9 pin connector to your motor. Unless your motor opens up easily, I would splice it. The first time I did it, it was quite hard to solder the thicker phase wires together and make a bundle that still fit thru a 12mm axle nut. Then I started using the metal forms out of smaller crimp connectors. The Hall sensor wires are easily soldered. I try to put the join in an area of the cable that doesn't get moved. That is shrink wrap in the 2nd picture, not the heavy crimp plastic,

View attachment 81866 View attachment 81867

I have the MXUS with KT WP controller and peripherals installed on my wife's Biria but was waiting on delivery of some solder seal wire connectors to connect the non-WP motor cable to a stub of WP male connector. I didn't strip much of the outer sheathing, only the minimum necessary which probably made things harder than they had to be. I did solder and shrink wrap one of the tiny 25g(?) wires, everything else was done with solder seal connectors which were easier, but still not easy. The 16g phase wires seem way undersized to power a motor but both the original harness and the extension that I bought for the WP connector had the same wimpy gauge wires.
It works, next thing is for her to see if it delivers enough assist. If not I'll put the rear geared hub kit on it, that will be more than powerful enough based on what testing I have done on an old mountain bike. I had intended the rear hub kit for a tandem bike we have but her Biria is the priority for now.

 

[EMGX]

Final assessment is that the old MXUS 36v hub motor paired with KT 11a/22a controller and a 36v battery (controller is dual voltage 36/48v) gives excellent assist. My wife rode it yesterday several miles and I did a fairly hilly 17 mile route with some steep and some long grades, total elevation gain ~1200ft per google maps. Very different experience than when in the past I had tried this motor in other bikes with the original controller that would just let the motor stall on steep hills. The motor stayed cool to the touch on the left side of the hub housing and only very slightly warm on the right side at the end of climbs. The wiring is sort of a mess but the best I could do with typical hub motor harness on this bike. Total success.

 

[djw54]

Final assessment is that the old MXUS 36v hub motor paired with KT 11a/22a controller and a 36v battery (controller is dual voltage 36/48v) gives excellent assist. My wife rode it yesterday several miles and I did a fairly hilly 17 mile route with some steep and some long grades, total elevation gain ~1200ft per google maps. Very different experience than when in the past I had tried this motor in other bikes with the original controller that would just let the motor stall on steep hills. The motor stayed cool to the touch on the left side of the hub housing and only very slightly warm on the right side at the end of climbs. The wiring is sort of a mess but the best I could do with typical hub motor harness on this bike. Total success.
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First post here as I'm looking into ebikes now. My wife and I each have this same Biria step-through, and it's great to see that it has potential for conversion, as it's a solid bike that we want to continue riding. Would you still endorse going this route? Any recommendation on what would be a workable front hub in today's market? What is the power output on the unit that you used? I'm plenty handy, including building up bikes and threading wheels in the past. Thanks.

 

[mclewis1]

I've been quite impressed with the Shengyi SX front hub (and rear as well but that's on a different bike). It's a small 3kg/140mm package and Grin rates it as a 300-500w class motor. Coupled with a BaseRunner controller I can regularly run over 1000w through it (but not for sustained periods of course as it will overheat). With a 52v battery and with either 27.5 or 700c wheels I max out around 45kph. The Grin package of the hub/wheel, BaseRunner and CA display/control isn't cheap but it's a top quality setup (with items like an internal temp sensor and power roll back if the motor is pushed too hard for too long) that has been bullet proof for me over the past 3 years of almost daily use in urban/suburban riding.

 

[AHicks]

The thing that puzzles me about the KT controllers is that they are both rated the same 11/22a but one is longer and heavier than the other. If it seems to supply too much current and makes the bike difficult for her to ride I can switch over to the smaller controller from the rear geared kit. The main reason that I wanted to switch the MXUS motor to WP connector is my two controllers have WP connectors to be compatible with the crank sensor and display/brake inhibitor/throttle wire WP connectors. As long as it works for her I think that I have finally found the right bike for my wife to keep her riding as long as possible.

Regarding "too much power" the KT's can all be set back/lowered VERY easily. That should not be a concern. I usually set them up so I get something around 75-90 watts when running in PAS 1. Even when set WAY back, the motors will still have PLENTY of punch at wide open throttle.

There are 2 popular sizes of small compact KT controllers. One has 6 mosfets and is usually rated at 17 or 20 amps. The second (larger one) has 9 mosfets and is rated at 22 or 25 amps. More mosfets = better ability to handle power and will run cooler all else being equal. The smaller one (17/20a) works fine on a 500w motor in normal usage. If you're thinking hills or hard play, I would go with the bigger one if possible.

 

[tomjasz]

I've been quite impressed with the Shengyi SX front hub (and rear as well but that's on a different bike). It's a small 3kg/140mm package and Grin rates it as a 300-500w class motor. Coupled with a BaseRunner controller I can regularly run over 1000w through it (but not for sustained periods of course as it will overheat). With a 52v battery and with either 27.5 or 700c wheels I max out around 45kph. The Grin package of the hub/wheel, BaseRunner and CA display/control isn't cheap but it's a top quality setup (with items like an internal temp sensor and power roll back if the motor is pushed too hard for too long) that has been bullet proof for me over the past 3 years of almost daily use in urban/suburban riding.

I was very disappointed to see them discontinue my Grinfineon controllers, but agree the basrunners installed in a Shan Shan or Reention case are quite amazing.