Best front DD hub under 6KG for cargo load ?

Hello,

The titles sums it up. According to ebikes.ca simulator, the 9c RH212 beats most of the competition; unfortunately, it's only available as rear version and a bit on the heavy side, so I'm looking at a similar motor for front fork that doesn't break the bank. Donor bike will be a long john with a small 20" wheel front. Expected load 150kg. Lots of hills. Any advice ?

thank you for your time,

qwerkus

A Basic 9C 2706 has nearly the same specs on the simulator, and is available in a front motor. 6.16kg.

Best hub for a bike like that is one in the rear. I'd want a geared hub mike a MAC, not a direct drive. Asking the front wheel to handle steering, traction, and propulsion is asking too much.

Drunkskunk said:

A Basic 9C 2706 has nearly the same specs on the simulator, and is available in a front motor. 6.16kg.

Best hub for a bike like that is one in the rear. I'd want a geared hub mike a MAC, not a direct drive. Asking the front wheel to handle steering, traction, and propulsion is asking too much.

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Why ? The main problem of front hubs is lack of traction because of classic bicycle weight distribution. This is much less likely to happen on a loaded long john. If the fork is able to handle brakes and bumps, traction from a motor should not be an issue. That why one of the best german long johns has a front motor: https://www.radkutsche.de/rapid/



Though I agree with you that I wouldn't want 6Kg there. Handling is already tricky on those bikes; probably a lighter geared hub would be the better option indeed.

Stick the big battery pack in a front basket to help with traction.

Or put the geared hub motor in back, optimize that for starting from dead stop and hills, and

set the DD up in front not for torque but coasting / speed maintenance and WOT.

I have been waiting for this to be released - Heinzmann Cargopower: https://www.heinzmann-electric-motors.com/en/system-solutions/bicycle-drive-systems/cargopower but it keeps getting delayed. I think the specs say 5.1kg, Carla Cargo are also using what I presume are test versions: https://www.youtube.com/watch?v=86YNkgiT26E

Otherwise hoping that Grin can release a front hub version of their GMAC motor.

You might try the trike kit front hub motor at Ebikekit. Its a slow motor, so it will tolerate the slow rpms common when hauling heavier loads, particularly up hills. It still won't haul unlimited loads up long steep hills, but does haul 400 pound loads up hills that are miles long with ease. The limit is simply the amount of copper and magnet size in a 9 c motor. It can be run up to 1500-2000w without burning it too quick. In the trike kit, its limited to about 1200w when run on 48v.

Its not a 9 c motor, but nearly identical. It will do what you need, unless its for san francisco or something crazy steep.


I think that heinzmann would fry if you rode up the rocky mountains weighing 500 pounds total weight. Like all gear motors, it would shed core heat poorly. It's not total torque that you need with a cargo bike. What you need usually, is good efficiency at lower rpms. That you get with a lower rpm motor of any type. What tends to happen though, is if you only have 1000w of power, you slow down too much on steeper hills, and overheat the motor. None of that matters much though, if you don't have hills to climb.


You are on the right track with a DD, and 20" rim will increase the load you can carry. But if you can find a larger front hub DD motor go with it. Better to carry a heavy ass motor able to handle 3000w, and use 500w, than overheat a 500w rated motor running 2000w. Get something with a 35 mm or wider stator, and give it a 48v 40 amps controller. Then you will zoom up steep hills heavy loaded, and still get great wh/mi when riding slowly on the flat. Big motor only uses big power when it goes fast, or goes up mountains. So go big.

dogman dan said:

You are on the right track with a DD, and 20" rim will increase the load you can carry. But if you can find a larger front hub DD motor go with it. Better to carry a heavy ass motor able to handle 3000w, and use 500w, than overheat a 500w rated motor running 2000w. Get something with a 35 mm or wider stator, and give it a 48v 40 amps controller. Then you will zoom up steep hills heavy loaded, and still get great wh/mi when riding slowly on the flat. Big motor only uses big power when it goes fast, or goes up mountains. So go big.

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Makes sense; unfortunately, the weak link on long johns is that prolonged steering bar, which already makes handling quite awkward (unless you get a version with cable steering). I'm not a fan of adding too much weight there - hence the 6Kg limit.

I would fit the motor on the rear, preserving steering lightness. Cargo weight is enough already. And, either use a custom slow winding lightweight geared motor, or a big DD hub to climb and speed.

MadRhino said:

I would fit the motor on the rear, preserving steering lightness. Cargo weight is enough already. And, either use a custom slow winding lightweight geared motor, or a big DD hub to climb and speed.

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Rear motors in long johns have 2 main problems:
1. Large wheel diameter = you need a super heavy motor to avoid overheating during climbs. In mountaineous regions like mine, hub motors don't make sense on anything larger than a 24" wheel.
2. Difficult start whithout motor. Say the battery is empty or the motor died and you had to stop because a kid lost its ball on the street, try starting again with 100kg load and a derailleur. There is a reason all quality cargos come wih IGH... So apart from the TDCM which is too weak for cargo, rear hub motor means derailleur which is a nogo for me. On a sidenote, this is also the limiting factor of a mid drive for cargo; only the super expensive rohloff can take on the extra weight + motor power while in a front motor setup, the excellent alfine 8 works great.

Yeah, I get it that lighter would be better. But you said 150kg if that's you, the bike, the battery, the motor and the cargo, then the typical 9c type dd motor will do you just fine, particularly in 20" rim.

I used the same motor as the trike kit in this bike, but a rear motor. 9c type motor from Ebikekit, in the 10 turn winding. Top speed was 18mph, so it could climb at 10 mph without making a lot of heat.

Bike, including up to 40 ah of battery was 100-120 pounds, me about 190. so nearly your 150k there with no cargo. Then the bike easily climbed my nearby test hill. 5 miles long, grade starting at 1% for a few miles, then 3% with the last two miles 6 to 8% grade, towing a 100 pound trailer. About 2000 feet of vertical gain, with no flat or downhill resting. just a long grind getting steeper and steeper. It kills geared motors easy peasy.

Never tested the limits beyond that, since the trailer was maxed out. so about 180 kilos, and the 9c type motors will do the climb in 20" wheel. This changes though, if you need to climb a mile or more of 10 or 12% grade, which is why I mentioned larger motors that can take 2000w or more for more than 30 min.

If you have trouble finding the slower wind 9c motor, it will still get to the top of a long 6-8% hill fine. It will just get a bit hotter, but not overheat. About 180kg is the limit for those motors in a 20" wheel. Just don't get the very high rpm version. 7 turn will work, just don't get into 5 or 6 turn.

If your hills are short, like half a mile, with a half mile down to cool a bit, you will be able to climb steeper hills. I speak only of limits to the motor on hills that are miles long, or more than 300 meters tall.


If your hills are not even close to 5% grade, and short, like a kilometer or less, then you could get away with a geared motor like in the bike you showed. That rig is perfect for amsterdam, but not san francisco.

How about this bugger: http://www.syimotor.com/productDe_5.html
Looks like a standart 27mm DD hub motor, only 1Kg lighter. Side cable exit is super nice. Maybe they have a front version ?



EDIT: Zero information about this motor online. Anyone has some experience with it? What's it's performance chart ? Thermal performance ? How about 1000W ?