2 Speed Xiongda hubmotor

[Green Machine]

Sometimes the problems are much simpler than you think....

And yes improper shifting could be the problem.

I heard for years that mid drives are bad on drivelines and i never see that on our bikes....but realized after selling a bunch of them a lot of ebikers simply dont know how to shift properly and shifting while climbing or under heavy power is murder on drive lines . plus ebikers tend to be over weight which can be hard on drivellins when coupled with not shifting properly.

The bbs02 has a reputation as an unreliable product it does not deserve... from people over riding the factory settings and making full power available so that any idiot who does not know how to ride a mid drive can melt the gear throttling up a hill in the wrong gear. in the factory settings they would be forced to pedal up that big hill anad would instantly change into a new gear (probably doing a bit of damage to there driveline since they dont know your not suppose to do that).


The BBSHD is overbuiilt to take more heat... weighs 3 pounds more... hard to get it hot so the gears dont get frocked.

imo was not the right solution. i might go back to selling the bbs02...focus on that for a while.

 

[bigoilbob]

If you want autoshifting, buy the motor from the manufacturer with their autoshifting controller. On a hill it will shift late, and in some situations it will hunt between gears. Each time it shifts wastes time and results in lost momentum on a steep grade as well as extra wear on the clutch. It limits the controller choices to special units made with the autoshifting algorithm built in. It doesn't know the wheel diameter, load on the bike or the gradient, or how far away the next stop is. A person shifting manually can do a better job. If you run in the wrong gear it either limits your torque or your top speed. The two speeds can be considered "torque" or "speed" mode, and you pick which one based on conditions and needs.

Some people feel a need for automatic transmissions, some don't. Some prefer manual shifting. If you have enough torque then shifting is not needed at all. The low speed gear selection of this small hubmotor is really for reducing motor heat and providing adequate torque while climbing steep gradients, or moving heavy loads. But when doing these things there isn't enough torque available to switch into high gear so you just stay in low. Autoshifting is not really needed. It is more like a "low range" vs "high range" on a 4WD vehicle - a mode selection rather than a shifting situation. This differs from an ICE engine where torque peaks in the midrange, a problem that BLDC electric motors don't have.

Using the search I find some Xiongda autoshifting controllers had problems, it is mentioned in other threads but without much detail.

Any gearmotor faces wear issues on clutches and gears. Subjecting them to extra wear from unneeded autoshifting is likely to reduce the service life.

What I found in my modelling for a folding bike climbing steep gradients was that shifting allowed climbing the grade while keeping motor heat down. It was a range selection, on that gradient shifting up would result in overheating and possibly stalling. You had to select low gear and stay there.

In any case Luna chose to use a different controller and stick to manual shifting. Looking forward to field test results to see how well it works. Hopefully someone with an autoshift controller will do actual comparison testing.

Alan B, I'm missing something in this post. Do you have any actual owner/operator experience with a Xiongda build with auto shift? Not rhetorical - you might well have some and I'm missing your implicit mention of it in your post. Thanks in any case.

 

[Alan B]

It sounds more like you are fishing for information to discount other people's writings, as if owning something makes a person expert about it. Owning one and using one gives certain specific experience with it, within the limit of the statistics of their experiments. But it hardly by itself makes one an expert. That takes more. A lot more.

I have 40 plus years of engineering experience, most of it working at a National Research Laboratory with systems including massive telescopes with more than 100 real time alignment motors operating in the ten nanometer precision regime, accelerators with hundreds of precision systems including motors, controllers and power supplies and I've been following this motor, and many others for the last six or so years including many tens of thousands of postings on ES and elsewhere. The same physics, mechanical, electronics, controls and other engineering properties apply to all these systems. At the National Labs we tend to push everything to the limits as that is required to do the leading edge Science.

Have you operated this motor in normal full size bicycle wheels, and with heavier loads? Small wheel loads are significantly less.
Have you any experience with the Luna variant?
Have you measured or calculated the dynamic forces on the Xiongda clutch and gears?
Have you modelled the motor heat loads on various gradients with the different gearing?
Have you calculated the integrated energy lost during the Xiongda controller shifting and the impact that has on momentum wasted during the lost time on steep gradients?

Users have reported damage to this and other gearmotors from hard clutch engagement. These are well known mechanical characteristics (weaknesses) of these systems. Many have reported hunting in the Xiongda autoshifting. This is a problem common to virtually all automatic transmissions under some circumstances of speed and load. Large wheels and heavy loads will generally accentuate these issues.

A quick search here on ES uncovered some automatic shifting problems earlier with this motor and some controllers. Reports of slow shifting and loss of momentum came from other users as well, not my personal experience. But it matches the math.

I've driven manual transmissions for about 50 years. It seems pretty easy to handle, and in a lot of cases manual shifting is better. Bicycles are generally manually shifted. Is this a problem that needs fixing?

Owner/operator experience is useful, but it does not go very deep in understanding the mechanisms and their full operating conditions, wear and stresses. You can't really tell if it is just a few shifts away from failure. One owner's experience is very small statistically. A few failures tells a lot more than a lot of "mine hasn't broken" results. A look at the manufacturer's whole experience would be much better, but we probably won't get that information from them.

I don't claim to be an expert on this motor. But I have experience that can be useful to apply to understanding and interpreting the reports we have of this motor.

I hope this is a great motor. Reading this and other threads on ES and elsewhere about this and other gearmotors has not been a totally positive experience. I look forward to more testing over a wider range of conditions by users of these newer improved variations. This appears to be a fairly unique design among hubmotors with the potential to be an excellent choice, especially for lighter builds with great torque for climbing steep gradients while retaining reasonable speed on level routes and without the extreme power and weight of larger hubmotors.

 

[LewTwo]

... plus ebikers tend to be over weight ....

dang, guess I need to start packing in the carbs

 

[bigoilbob]

It sounds more like you are fishing for information to discount other people's writings, as if owning something makes a person expert about it. Owning one and using one gives certain specific experience with it, within the limit of the statistics of their experiments. But it hardly by itself makes one an expert. That takes more. A lot more.

I have 40 plus years of engineering experience, most of it working at a National Research Laboratory with systems including massive telescopes with more than 100 real time alignment motors operating in the ten nanometer precision regime, accelerators with hundreds of precision systems including motors, controllers and power supplies and I've been following this motor, and many others for the last six or so years including many tens of thousands of postings on ES and elsewhere. The same physics, mechanical, electronics, controls and other engineering properties apply to all these systems. At the National Labs we tend to push everything to the limits as that is required to do the leading edge Science.

Have you operated this motor in normal full size bicycle wheels, and with heavier loads? Small wheel loads are significantly less.
Have you any experience with the Luna variant?
Have you measured or calculated the dynamic forces on the Xiongda clutch and gears?
Have you modelled the motor heat loads on various gradients with the different gearing?
Have you calculated the integrated energy lost during the Xiongda controller shifting and the impact that has on momentum wasted during the lost time on steep gradients?

Users have reported damage to this and other gearmotors from hard clutch engagement. These are well known mechanical characteristics (weaknesses) of these systems. Many have reported hunting in the Xiongda autoshifting. This is a problem common to virtually all automatic transmissions under some circumstances of speed and load. Large wheels and heavy loads will generally accentuate these issues.

A quick search here on ES uncovered some automatic shifting problems earlier with this motor and some controllers. Reports of slow shifting and loss of momentum came from other users as well, not my personal experience. But it matches the math.

I've driven manual transmissions for about 50 years. It seems pretty easy to handle, and in a lot of cases manual shifting is better. Bicycles are generally manually shifted. Is this a problem that needs fixing?

Owner/operator experience is useful, but it does not go very deep in understanding the mechanisms and their full operating conditions, wear and stresses. You can't really tell if it is just a few shifts away from failure. One owner's experience is very small statistically. A few failures tells a lot more than a lot of "mine hasn't broken" results. A look at the manufacturer's whole experience would be much better, but we probably won't get that information from them.

I don't claim to be an expert on this motor. But I have experience that can be useful to apply to understanding and interpreting the reports we have of this motor.

I hope this is a great motor. Reading this and other threads on ES and elsewhere about this and other gearmotors has not been a totally positive experience. I look forward to more testing over a wider range of conditions by users of these newer improved variations. This appears to be a fairly unique design among hubmotors with the potential to be an excellent choice, especially for lighter builds with great torque for climbing steep gradients while retaining reasonable speed on level routes and without the extreme power and weight of larger hubmotors.

Thx for your resume, but no personal experience and you can't point on this thread to any of the other "shifting problems". As a lifelong petroleum reservoir simulator, I also value models. But if there's actual user data, bingo. Yes, a downshift pauses for maybe 1.0-1.5 seconds. And you lose ~0.5-3 m/h, depending on grade. You not only get used to it, but totally forget about it. As I said, I've never had to put my feet down on a shift. FMI, is THIS the only "shift problem", or are there others? B4 answering, ALL auto transmissions can "hunt". Whether pulling my camper trailer with my truck or climbing a hill on my Bikee E2 recumbent tandem, with 2 aboard, I assess and manually downshift as appropriate. When I judge that my load has dropped enough, I return to auto. Common sense, NOT a transmission problem. Particularly, has anyone reported a link between shifting and failing, per your " You can't really tell if it is just a few shifts away from failure. "? In conclusion, if "pausing" and "hunting" or your only gripes about auto shifting, BFD. And yes, I would still like to see a comparison of internal temps v repeated loads to failure (kind of a series Goodman stress diagrams v temp) for the nylon gears. I'm lookin' good so far, but that DOES concern me....

 

[Alan B]

There is a lot of data on gearmotor failures.

Review the threads for other similar small gearmotors such as the Cute Q motor series (and others) to learn about the properties of the type. Even larger gearmotors have plenty of correlation data between elevated temperatures and gear failure, and between shifting shock and clutch failure. The dataset for this motor is not wholly contained in this thread, there are many others, and this motor's dataset is somewhat small. Motors that aren't two speed still have shifting shock between freewheeling and engaged. A Google search for "Xiongda failure" presents in excess of 78,000 results. Not all of these are relevant of course, and the sheer number makes it hard to find a particular article, but this does not mean they don't exist. Over 500 hits on ES alone. docnjoj had shifter problems and multiple failures, it appears that he no longer uses the Xiongda motor. I also see some failures of the display in wet conditions. So there may be advantages to a different display.

Some major vendors have completely stopped selling the smaller gearmotors due to their high failure rates.

Your small wheeled, light bike presents a reduced load. Losing 1.5 seconds of time during climbing on a steep gradient is a significant loss of powered time. If it hunts then the loss could be 4.5 seconds or more. I recall someone writing that autoshifting was so slow and late that it was not useful.

You have not presented any examples from your experience of autoshifting being necessary or important. Are there any you wish to share?

In the case where your travel transitions from level to a steep 15% gradient, does it hunt? How much improvement in average speed does manual shifting earlier, and staying in low gear make?

How much do you roll the bike backwards? Does it ever "lock up" when rolled back? The Xiongda contains a mechanism designed to prevent this lockup. Does it work reliably?

How many miles do you have on your Xiongda?

Do you ride it in the rain?

Have you experienced any problems aside from the hunting and slow shifting?

 

[Triketech]

Definitely a cool concept. But not for everyone.

Even today after a century of refinement, automatic transmissions just don't always respond to the driver's needs. (Although the 2016 Subaru has come remarkably close with a CVT. Software.) To develop and refine the controller for an optimized autotune feature might be a bit costly on low production runs.

Always interesting to observe consumer experiences with innovative products. Please keep up the objective and non-offensive comments.

 

[cycleops612]

Is it just me, or is it obvious that ANY non radar~ automatic wont anticipate a hill downshift as well as a person?

I can see each mode on the XD having its good points.

The issue for most would be, how easy is it to toggle between modes? I imagine the answer is "VERY EASY".

If, as users here say, shifts are butter smooth, then thats awesome alone. I take it as they computer control the shift/meshing of gears perfectly, even under throttle. A manual shift is just a touch of a button i presume.

An auto mode in many other situations, has the benefit of taking the guesswork out of ideal rpm shift points.

It also bears re-iterating if correct, that even IF, god forbid, you strip gears, with the cheap spares handy, its not a big job to replace the innards - no respoking involved. So invest in spares when u buy, for peace of mind?

 

[spinningmagnets]

with the cheap spares handy, its not a big job to replace the innards - no respoking involved. So invest in spares when u buy?

I recommend this to all new ebikers. I also recommend buying two throttles from the same vendor so the plugs are identical. Its not that throttles are especially problematic, but...if there is ever any issue with the system, its fast and easy to swap-in just the plug for a spare throttle and lift the rear wheel for a test. Throttles are fairly affordable, so that alone can save you a few days waiting for a spare to arrive when a problem comes up.

I wrote up a tutorial with lots of pics for popping open a Bafang BPM (and MAC), which are very popular geared hubs. I showed how to easily double the thickness of the phase wires, and to then add a temp sensor. As long as you didn't get them too hot, you could run significantly more amps than they were factory-rated for. The plastic planet-gears acted as a "mechanical fuse" so if you damaged them, a repair was fairly fast, cheap, and easy. You just had to remember to dial-back your amps about 20% to prevent them breaking again the second time around (your hills might be steeper and longer than my hills, I might be heavier than you, etc). The lighter the rider/cargo, and the flatter the terrain...the more amps you could use as a temporary peak.

Bafang BPM
https://endless-sphere.com/forums/viewtopic.php?f=16&t=51237

MAC
https://endless-sphere.com/forums/viewtopic.php?f=16&t=51310

 

[2old]

My application might be anomalous, but many rides in socal are constant ascents for 2,000' - 3,000' followed by flat or downhill. Of course, this is where mid-drives excel, but if I purchase this kit, it will be interesting to see how far it will climb. For my application, manual shift is preferable (TO ME).

 

[spinningmagnets]

The stock dashboard reportedly works fine, but it won't track the voltage of a 52V / 14S battery pack from Luna or em3ev. I am sure there will be several 26-inch wheel builds, and I am also curious to see how much these hubs can be loaded in a 20-inch wheel.

 

[Alan B]

The Xiongda hubmotor is a retro-direct 2 speed system. A retro direct system has two gear trains always has gears fully meshed, but they rotate in opposite directions. There are two one-way clutches such that power can only be transferred in one direction to the wheel. When the motor rotates in one direction you get one gear ratio through one clutch and gear train while the other clutch is rotating the opposite direction and is thus disengaged. When the motor rotates the opposite direction the situation reverses and power flows through the opposite clutch and gears with a different ratio. Gears can be replaced by chains or belts in variations of this design. Retro direct designs are very old, however the Xiongda design variation seems to be fairly new.

So the only thing that engages and disengages are the two one-way clutch mechanisms.

From a control perspective a gearshift cycle needs to decelerate the motor, reverse it, and accelerate the motor until the clutch engages while taking care to keep the motor current low to avoid shocking the clutch and meshed gears. After the clutch engages and the gear slack is taken up it can ramp up the motor current.

The motor speed ramping rate must be carefully controlled to avoid slamming the clutch and gears, which is why the shifting time needs to be moderated and slow.

The problem with rotating the wheel backward is this effectively locks both clutches and attempts to rotate both gearsets backwards. Since they turn the motor opposite directions this results in one or more gears attempting to rotate in both directions at the same time.

The Xiongda design has a feature to prevent this. Here's a video that shows the Xiongda's internal operation:

https://www.youtube.com/watch?v=qzw8MKvErtw

Toward the end of the video you can see the special mode where the ring gear rotates either direction, its one way clutch has been deactivated. This allows the wheel to be rotated backwards without engaging both clutches and jamming the gears. This mechanism depends on the last application of motor power being in one particular direction.

These clutches are roller clutches. They depend on close tolerancing, proper materials, correct spring forces and proper lubrication to operate properly.

 

[Alan B]

It doesn't matter who makes the battery, the display's meter has a limited range that doesn't cover the higher voltage batteries. This is common on these 48V systems when used with a 14S 50 or 52 volt battery, it happens with many BBSHD displays for example. They read a maximum value and don't change until the voltage drops below that value. So they are not useful at the start of the discharge cycle, but later they may come into range. One I have with a bar graph indicates full until rather late in the discharge cycle, so when it falls off full you are almost out of range.

Note that 14S 3.6V cells make a 50.4 volt battery while 3.7V cells make a 51.8V battery. These are commonly rounded off to 50V or 52V values. The nominal values for the cells comes from the cell manufacturer's data sheets and varies depending on the materials in the cells and their rating process. In practice there is little difference between these packs and the voltages actually operate over a range above and below these values anyway.

 

[spinningmagnets]

The stock Xiongda display that I received in the kit I bought a couple years ago (I don't know the exact date) is set up to read 36V and 48V battery packs (10S / 13S). It would be quite easy for the factory to add a 14S battery read-out option (or even 60V / 72V...not that using those voltages are a good idea or not). In fact, if the new stock Xiongda display could show the status of a 14S battery pack, I wouldn't know...but perhaps someone in this thread with a more recent kit could try that to see?

 

[Samd]

Why the fascination with 7% more voltage? Whats wrong with 13s top speed?

I smell gimmicks. This is a tiny kit. Just get kunteng to set the phase timing to simulate it and enjoy a raft of commoditised 13s batteries.


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[spinningmagnets]

There's certainly nothing wrong with running this motor at 36V or 48V.

 

[Samd]

Indeed. "7% more top speed of not much top speed is not much more. "


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[Alan B]

1/13 = 7.69% so I would call that 8%. It should yield 8% more speed and E squared over R gives 16% more acceleration until the current limit kicks in and then you get limited to the 8% more power.

I have standardized on 14S so I don't even have any 13S batteries. But Samd is right, there are more 13S 48V batteries and nothing wrong with going that way.

So far the only downside I've found with 14S is the voltage and state of charge readouts not working properly.

 

[Samd]

Haha its 0.7% more of a tiny speed. Awesome! Should push that 20.2 mph top speed all the way up to "20.whocares"

Seriously all gags aside there is a dearth of 13s batteries around. If we really want to get more people on ebikes ahead of profiteering then the battery investment is the key.

Lets take a slippery slope approach. Someone should bring out 15s batteries to suit all the 63v caps on controllers. "14s batteries - so last year!" Haha.


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[cycleops612]

My application might be anomalous, but many rides in socal are constant ascents for 2,000' - 3,000' followed by flat or downhill. Of course, this is where mid-drives excel, but if I purchase this kit, it will be interesting to see how far it will climb. For my application, manual shift is preferable (TO ME).

The good news is low is very low i hear, and hubs better suit its separately geared pedal assist.

IMHO only, the reality behind the alleged gear stripping is too much heat on the nylon gears making them softer. Your climbs sound extreme to me.

A fair indicator is its sold by XD as a 350w 36v motor as i recall, so even 750w sounds an awfully big ask of it, let alone ~1500w.

Greenmachines 48v rig should help reduce heat at a given power level tho - correct?

 

[leelorr]

For me, it's the fact that I could share my $550 14s battery between my other Ebike and one with this hub motor kit. in fact, I held off buying a hub motor kit from "BMS Battery" recently because all of their small sine wave controllers could only handle 36 volts.
I thought I saw somewhere that the display could show the battery voltage (UBE setting?)? If so, that would be perfect. I don't really need to see battery display "segments" if they are inaccurate, the battery voltage would tell me everything I need to know while riding.

 

[spinningmagnets]

Again, nothing wrong with running just about any ebike kit at 48V, that being said...my first 14S battery pack was purchased a few years ago from em3ev, no complaints so far. Both the Xiongda and Luna displays will read a 48V battery pack. Cycle Analyst will read them all...

 

[2old]

+1 with leelor; I have a 52V battery that is being used on two systems; don't plan on 48V until this one dies. Therefore if I get an Xiongda kit, that's what will power it too. I can live with the battery display conundrum.

 

[bigoilbob]

"Your small wheeled, light bike presents a reduced load. Losing 1.5 seconds of time during climbing on a steep gradient is a significant loss of powered time. If it hunts then the loss could be 4.5 seconds or more. I recall someone writing that autoshifting was so slow and late that it was not useful."

You have not presented any examples from your experience of autoshifting being necessary or important. Are there any you wish to share?"

* My "small wheeled bike" is actually heavy, and carries 2 riders And because of the way gravity works, loss of speed during shifting is not dependent on weight anyhow. Also in practice, you can not downshift a Xiongda manually any faster than it downshifts automatically. Please point me to the page of any poster who says otherwise - the elusive "someone".

* "Hunting" is the repeated downshift, speed up, upshift, failure to maintain speed upon upshift, and then resultant repeat of the downshift. It has NOTHING to do with "4.5 seconds or more" of delay.

* The advantages of autoshifting are intuitively obvious. One less thing for the rider to think about. Improved motor life from shifting that is programmed to reduce motor shock and to keep the motor in it's best range. I actually prefer manual shifting cars, trucks, motorcycles, but like the fact that my wife can exploit 2 speed bicycle motor operation without having to think about which gear she is in. If you don't like autoshift, that; your preference. But I have yet to see any posts pointing out any problems with autoshift that would be reduced/solved without it being available. Please point out the thread page of any such posts...

 

[LewTwo]

Why the fascination with 7% more voltage? Whats wrong with 13s top speed?

Well if you are superstitious (and there are people who are) then it is said that 13 is an unlucky number. Other than that it is difficult to 'split' a 13S pack while a 12S or 14S pack can be evenly split. Also a '13S' (13*3.6) pack is closer to 46 than 48 so why even call it 48 volts? Of course someone with make the argument that it is 13 x 3.7 volt = 48.1 volts (in that case explain why 10 x 3.7 = 36 volts).