2 Speed Xiongda hubmotor

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Re: 2 Speed Xiongda hubmotor

Postby Ozzzz » Tue Sep 12, 2017 1:03 pm

Ok, thanks. I'm thinking mine (in the 27.5) may in fact be a 135mm axle. Which looks to mean it lacks an axle nut..

I used sheldon browns lever method to bend my fat bike steel frame, one side at a time.
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Tue Sep 12, 2017 2:03 pm

knutselmaaster wrote:No 135. It didn't cost much effort to put it in, maybe because after the "S-bent" rear stays.


Okay, thanks. Both chain and "seat" stays on mine also have S-bends.

In addition, the chain stays are flattened to produce a concave area adjacent to the rim&tyre, which should make the spreading occur with less stress and spring-back. (I hope.)

Still stuck for how to ensure the spread is even.

Another approach I've considered is to leave the existing wheel in-place and slide a pair 1mm thick slotted washers inside the droop-outs. Ride for a few days and then add another pair, etc. until I achieve the 5mm each side I need. The idea is that by doing it evenly and gradually, the tension of the wheelnuts and the vibration of road will gradually 'set' the spread. And if it starts to go one way or the other, then perhaps an extra washer on one side for a week or two would correct it.

It'd take a while, but I'd be able to see if things are going wrong before they become critical and correct them, and I keep a usable bike the whole time. Thoughts?
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Tue Sep 12, 2017 3:09 pm

Ozzzz wrote:I used sheldon browns lever method to bend my fat bike steel frame, one side at a time.


Thanks for the pointer. I hadn't seen that. I especially like the simplicity of the "string & ruler" method of checking symmetry.
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Re: 2 Speed Xiongda hubmotor

Postby d8veh » Wed Sep 13, 2017 6:02 am

To stretch frames, I fill the gap in the frame with planks of wood, then I knock in another one, like a wedge to force them outwards.

planks.jpg
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Re: 2 Speed Xiongda hubmotor

Postby Alan B » Wed Sep 13, 2017 10:21 am

I used a threaded rod, nuts and washers through the dropouts.

But the problem with all these solutions is they bend the bike unequally, since the two sides never have exactly the same bending characteristics. There is a need to bend each side independently, which is more difficult.
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Wed Sep 13, 2017 1:49 pm

Alan B wrote:But the problem with all these solutions is they bend the bike unequally, since the two sides never have exactly the same bending characteristics. There is a need to bend each side independently, which is more difficult.


Indeed. The Sheldon Brown method uses the integrity of the front triangle and the floor to apply force to the two sides independently, which is great on a rigid frame; but trying to apply it to my frame, with "seat post" being independent of the front triangle, means that it would be the pivot points that would take the strain and whilst the main pivot can probably take it, those by the spring unit won't.

I'm quite confident that using a scissor jack will give me all the leverage I need -- and give me a high degree of control on the spread -- but managing the distribution of the spread is eluding me for the moment.
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Re: 2 Speed Xiongda hubmotor

Postby Alan B » Wed Sep 13, 2017 4:18 pm

If you lay the bike on it's side and use the scissor jack against a long wood block on the side against both the chainstay and seatstay tubes at about the tire, and a wire from the dropout to the jack top, then to the lower "seat tube" midway between the stays you can bend one side independently from the other. All the forces are within the one side of the rear triangle, none are on the pivots. I haven't tried this, so no guarantees. Go slow and release to check the spacing between the dropouts, expand half on one side and then swap to the other side. A small hydraulic jack may be better than a scissor jack for this. Proceed at your own risk. :)
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Re: 2 Speed Xiongda hubmotor

Postby Ozzzz » Wed Sep 13, 2017 6:12 pm

Something I probably would have done first, before bending, would be to check how parallel the dropouts are and if they are indeed centrered (if they are supposed to be). Along with string/measurements off the seat-stay, I used two threaded bolts (in place of an axle) and bent each dropout tang to get the bolt ends pointed at each other. This needed a big correction after bending the frame but I have a feeling they were not very even nor parallel to begin with, from the factory (ie. was more concerned with not putting a bending force on the tightened axle than getting the drop width precise).
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Wed Sep 13, 2017 7:55 pm

Alan B wrote:If you lay the bike on it's side and use the scissor jack against a long wood block on the side against both the chainstay and seatstay tubes at about the tire, and a wire from the dropout to the jack top, then to the lower "seat tube" midway between the stays you can bend one side independently from the other. All the forces are within the one side of the rear triangle, none are on the pivots.


Interesting.

It would be imperative to position (&fix) the block at exactly the same point on both stays on both sides of the the bike. (Doable with care.)

Of more concern is the "wire". That's going to have to be strong enough to apply enough force to overcome the elastic-plastic transition of the steel. Something like a towing hawser. The only thing I can think of like that is the cable in my garage doors, and the wife would not be a happy bunny, even if was convinced it up to the job :)

Nice bit of lateral thinking though.
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Re: 2 Speed Xiongda hubmotor

Postby Alan B » Wed Sep 13, 2017 8:16 pm

I do something similar with ratchet straps, the bike tubing is not all that strong. In that case I spread the frame to reinsert the axle rather than bend it permanently, (and do both sides at once) by putting the strap through a large PVC pipe, it doesn't take that much force to bend steel bike tubing. But for the permanent bending I would use small stainless aircraft type cable. I'd rather the bend be over some distance, so fitting the wood to the tubing would be even better to avoid a kink.

Another way is to use a couple of 2x4's or similar to make a lever and a fulcrum block, then generate the force with a threaded rod, stacks of washers and a couple of nuts. This would be more precise if a little slower to operate.
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Re: 2 Speed Xiongda hubmotor

Postby bigoilbob » Thu Sep 14, 2017 9:47 pm

"My reply from Bonnie gave these power options "Rated 24V250W/36V250W/48V300W". And 100/110/135/145/155mm depending on front/back thread-on/lock-on v/disk brake."

Buk, you got more complete info from Bonnie than I did. NOT a diss on Bonnie. But to answer your question, what I called the "skinny" version, is, I believe, ~110mm. I was blessed with a thick, steel , front fork, and enlarged it to handle my 48 volt hub. I'm no expert, but I don't think the thicker versions have any stronger innards, more windings, or anything like that. But I hope that fora readers correct me if I'm wrong.
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Fri Sep 15, 2017 9:03 am

bigoilbob wrote:what I called the "skinny" version, is, I believe, ~110mm. I was blessed with a thick, steel , front fork, and enlarged it to handle my 48 volt hub.

Okay. That's tallies with the front wheel motor with disk brake. (The v-disk front is 100mm).

bigoilbob wrote:I'm no expert, but I don't think the thicker versions have any stronger innards, more windings, or anything like that.


You're right. The different widths are purely down to external extras. A disk brake adds 10mm; a thread-on freewheel 35mm; a lock-on cassette 45mm.

Internally, the only differences are the gauge and number of turns in the windings.

These are tailored to your choice of input voltage: 24v/36v/48v to produce a motor constant Kv, to match the torque produced to your chosen wheel diameter.

I did ask Bonnie about the possibility of buying one motor and running it at 36V with the option to upgrade to 48v at some later stage and she made it very clear that this was not a good way to go.

A 48V-wound motor would deliver disappointing performance when run at 36v; and a 36v-wound motor would run faster with more torque at 48v, but in her words "be burnt down very quickly".

She did offer me the choice to have them supply a 48V-wound stator and assembly instructions at some future point if I chose to upgrade, but at my expense and risk. Which is fair enough.

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Re: 2 Speed Xiongda hubmotor

Postby knutselmaaster » Fri Sep 15, 2017 1:18 pm

As the 2-speed motors have quite a big width at a big diameter, one should check if the fork doesn't narrow down near the axle, especially at the front. A lot of front forks get less wide at a few centimetres from the axle and that may cause the motor not to fit.
Don't only check the width at the axle, but also it needs to be 100mm wide until at least 60mm from the axle.
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Re: 2 Speed Xiongda hubmotor

Postby Buk___ » Fri Sep 15, 2017 2:01 pm

knutselmaaster wrote:As the 2-speed motors have quite a big width at a big diameter, one should check if the fork doesn't narrow down near the axle, especially at the front. A lot of front forks get less wide at a few centimetres from the axle and that may cause the motor not to fit.
Don't only check the width at the axle, but also it needs to be 100mm wide until at least 60mm from the axle.



It's a good point. Luckily for me the frame I'm using is designed for a 160mm disk, which is bigger than the 132mm max circumference of the motor, so both seat stays and chain stays are well out of the way.
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Re: 2 Speed Xiongda hubmotor

Postby qwerkus » Sat Sep 23, 2017 5:31 pm

Hello, I'm considering the 2 speed xiongda motor for a second build, with more torque in mind. Sadly the motor seems very wide. Is there any chance it could fit into an aluminium 135mm disc rear frame ? Cold bending aluminum is not advisable, so I guess I only have +-2mm of spare room.
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Re: 2 Speed Xiongda hubmotor

Postby Ozzzz » Sat Sep 23, 2017 10:11 pm

qwerkus wrote:Hello, I'm considering the 2 speed xiongda motor for a second build, with more torque in mind. Sadly the motor seems very wide. Is there any chance it could fit into an aluminium 135mm disc rear frame ? Cold bending aluminum is not advisable, so I guess I only have +-2mm of spare room.



You have enough room for a single speed on a 135threaded (disc) motor option.
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Re: 2 Speed Xiongda hubmotor

Postby qwerkus » Sun Sep 24, 2017 5:51 am

Thank you for your reply. Sadly single speed is no option for me; my knees can't handle it anymore. 7s would be great, but maybe even a 3x3 setup could work, if i manage to space the gears enough. Otherwise, it s going to be the tsdz2.
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