Best geared hub motor for slow climbing

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killerisation

1 mW
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Jun 27, 2018
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Hi All,
I'm after a front motor for a tandem mountain bike, for help climbing at 3-8mph. PAS only. Would need to pull away from a standing start on a 20% incline with a 200kg load with maybe 300W of pedal power. Front wheel will be a fat 26er.
I'm considering the Xiongda YTW-06 and the Xiongda 2-speed motor. Which would you choose? Are there any others I should be aware of? Ideally I would have the controller integrated into the hub but they appear not to be that reliable.
 
MAC with 12T or 14T winding will nearly climb up a wall, see yourself -> motor simulator @ ebikes.ca
 
I see what you mean. I think that's a bit more than I need actually - around 500w should be enough. I'd also like to keep additional weight to a minimum and would prefer hub diameter to be <6" if possible. 44mm flange spacing is a bit narrower than I'd like too. Hub width is not so important as I haven't chosen a fork yet.

How do the two Xiongda motors compare in this context?
 
Further research suggests the Xiongda 2-speed motor is the more suitable of these two.
But how does it compare at low speed to the Bafang RM G060.350.DC?
Bafang more torque over 10mph but less below?
 
How do you think a MAC motor is too much for the job? 20% grade with 200kg is no fooling around. Even the mighty MAC 12T, helped out with 300W of pedal power will overheat in about two minutes of 20% grade, according to the Grin calculator. And it'll be chugging along at less than 5 mph. I'd go for the 14T model on 36V and at least 30A worth of battery and controller.

You can build a decently strong wheel on a MAC motor. Use cross-1 lacing with all the spokes outside the hub flanges, and lace to the opposite side of the rim if the spoke holes are staggered.

My usual first choice for 26" hub motor builds is the Weinmann DHL42 rim with 4mm stainless washers under the nipple heads. It's not an elegant rim, but it's super strong, super cheap, and easy to get. If you want something fancy and pretty, the new version Velocity Cliffhanger is very nice and plenty strong, but not structurally equal to DHL42.
 
Its still a sport bike, both riders would be pedaling hard in a position optimized for generating power. I just want it to be roughly equivalent to a third person pedaling so they wouldn't have get off and push.

I think I've decided to go for the 2-speed motor controlled by a torque sensing bb. The front wheel will have a fat tire though, so I'm looking at rim widths around 65-100mm. Whats the strongest one of those you know of? Weinmann DHL80?
 
killerisation said:
Its still a sport bike, both riders would be pedaling hard in a position optimized for generating power. I just want it to be roughly equivalent to a third person pedaling so they wouldn't have get off and push.
Click to expand...

The hub motor equivalent of a third person pedaling won't get you started from a stop on a 20% grade. I see where you're coming from, but you've described two very different performance requirements.

I think I've decided to go for the 2-speed motor controlled by a torque sensing bb. The front wheel will have a fat tire though, so I'm looking at rim widths around 65-100mm. Whats the strongest one of those you know of? Weinmann DHL80?
Click to expand...

My experience with DHL80 isn't good. I haven't come across one with a good rim joint yet. On the other hand, DHL65 has been awesome and the one build I've done with DHL101 was also good.

I'd go for DHL65, to be able to use either fatbike tires or relatively normal 26 inch tires. Anything from about 26 x 2.3" on up will work acceptably on a 65mm rim. That means being able to use tires like Schwalbe Big Apple or Maxxis Hookworm as well as dedicated fatbike tires.

If you're keen to use 4" to 5" tires at very low pressures, like less than 10 psi, then a 100mm rim would be a good idea.
 
With the low speed climbing you need on 26" fat tires why not use a mid motor that will be equally geared down as the riders?
 
Thanks for the rim advice. I decided against a mid motor because being a tandem there is already double the power going through the drivetrain and I didn't want to overload it. Also, I wanted the conversion to non-powered to be quick & easy. There are performance benefits of being all-wheel drive off road too.
 
killerisation said:
Its still a sport bike, both riders would be pedaling hard in a position optimized for generating power. I just want it to be roughly equivalent to a third person pedaling so they wouldn't have get off and push.

I think I've decided to go for the 2-speed motor controlled by a torque sensing bb. The front wheel will have a fat tire though, so I'm looking at rim widths around 65-100mm. Whats the strongest one of those you know of? Weinmann DHL80?
Click to expand...

Just ran across your post. Coincidentally, I checked with Xiangda on the availability of a torque sensing crank attachment for my 48 volt 2 speed front hub yesterday. Not available. But I'm lazy, so I like my cadence sensor...
 
Hello don't you fear the lag between the 2 speeds? I have exactly the same concern. I would like to buy a ytw06 but at xiongda they don't look confident with this motor. I told them i want a 2wd bike with 2 48v ytw06 and they suggest another motor the aikema sx100. But jiabo75t2 is lighter.
 
Best geared hub motor for slow climbing would be one in a 10 inch wheel. supposing you can find one in a mag wheel that small.


Overload a geared motor, of ANY wind, ( 300 total pounds weight or more) and ride it slow up 7% grade, and you will smoke that motor down in about 3 miles.

It CAN do short climbs, even fairly extreme steep. But it better be DAMN short! And, if you can pedal enough to keep speed up to 15 mph on a long grade, you will be ok. But slow to 7 mph with that motor on a long grade, and it will make half its power into heat. or more. Ever put your hand on a 100w bulb? Same thing inside your motor, or more like 400w.

You need a mid drive for your application. Hub motors slow up hills will die, unless very lightly loaded. The xionga would be the best to try it with though, since it is different from typical hub motors. I have not personally tested to destruction, an xionga.
 
Chalo said:
killerisation said:
The front wheel will have a fat tire though, so I'm looking at rim widths around 65-100mm. Whats the strongest one of those you know of? Weinmann DHL80?
Click to expand...
I'd go for DHL65, to be able to use either fatbike tires or relatively normal 26 inch tires. Anything from about 26 x 2.3" on up will work acceptably on a 65mm rim.
Click to expand...

Update:
I've been building pedicab wheels on rims about the same width as DHL65, and they work great with tires as narrow as 2.1" or even narrower. A nominal 2.1" tire measures an actual 2.7" on that rim.

IMG_6949.jpg
 
bigoilbob said:
Coincidentally, I checked with Xiangda on the availability of a torque sensing crank attachment for my 48 volt 2 speed front hub yesterday. Not available. But I'm lazy, so I like my cadence sensor...
Click to expand...
You can get one from Grin Tech http://ebikes.ca , and if your controller doesnt' support torque sensing you can use the Cycle Analyst v3.x from them to interpret it into a throttle signal for the controller you already have.
 
Many thanks, amberwolf. I just started a new topic to get the very answer you provided. I'll pursue it with the vendor you referred me to.

I'll try and check out this forum more often, so I'm giving instead of just taking from it.

Appreciate the help, aw....
 
Jean said:
Hello don't you fear the lag between the 2 speeds? I have exactly the same concern. I would like to buy a ytw06 but at xiongda they don't look confident with this motor. I told them i want a 2wd bike with 2 48v ytw06 and they suggest another motor the aikema sx100. But jiabo75t2 is lighter.
Click to expand...


You don't have to get into a situation of losing momentum while shifting. My Lishui controller, and presumably others let you keep your motor in low gear with the push of a button. While on the hill you just go low and slow. When you crest you return to auto mode and speed up.
 
I bought a Aikema Q128H because it is 800W and a slow (200rpm) wind, but still you can't climb slower than 8mph (700C) before it gets inefficient and generates too much heat. Fortunately it is powerful enough so I can manage 8mph up pretty steep hills.

The only better geared motor for climbing is the Xiongda 2 speed. But I'm not so sure you can easily use a CA3 to add a torque sensor, does the CA3 support motor reversing in a way that would work well for shifting gears on the Xiongda? Adding a CA3 to the Xiongda display gets clunky.

I am using a CA3 and a torque sensor with the Q128H and a KT controller and no KT display.
 
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