Electric kits vs. new bike

[Jeremy]

No orbital gear hub motor bike has the same drag as a normal bike.

That I have already clearly accepted, twice, so please don't tell me I'm wrong when I had already agreed this point. You wrote this though, which is what I take issue with, as it seems unfair:

In practice on the road, all hub motor bikes are a pain to pedal without power compared with the Panasonic system, there being no comparison.

"All hub motors" includes many, like the Crystalyte, Goldenmotor etc, that have no gears, rollers or other mechanical connection (other than bearings) between the axle and the hub. Quite obviously a gear-less hub motor cannot be significantly different to a normal hub, particularly as they most probably have better bearings than some cheap bike hubs. I can also say with confidence that the freewheel drag from the roller drive TongXin seems very low, it certainly doesn't feel as if it will be significant, even at speed. This is further borne out by the Brompton Nano road test, where the ease of pedalling resulted in the rather extreme range reported!

If you are being specific about one particular hub motor, based on your experience, as I believe you are, then it seems unfair to imply that all motors of this type suffer from the same defect to the same degree.

Jeremy

 

[Tiberius]

If I understand correctly, the Panasonic system drives the chain. So at the very least, there is still a sprocket rotating when its turned off and the rider is pedalling. It shouldn't be that different in drag to a well engineered hub motor. If they both have a freewheel to disconnect the motor, surely there are broadly equivalent amounts of rotating parts left turning.

Nick

 

[flecc]

Jeremy, this arose from my answering specifically a question about the Forza versus the Agattu, from which it is abundantly clear that I was speaking of the mainstream orbitally geared hub motors. Do you really require me to state in every subsequent reference all of those italicised words, when I come in here to post in help of other members as I was doing then, and not to have to defend myself as I increasingly seem to have to lately?

As for your comment on experience, I've had a long association with e-bikes and can instantly recall ten hub-motor bike/kit models and six Panasonic equipped bike models that I've experience of over the years, plus ownership of both types. You're aware of the limits of your experience in this area.

And that highlights the difference. Yours is a subjective comment, mine is based on experience of the comparisons. The fact that a rider like yourself or Frank Curran find a motor easy to pedal has no meaning in comparison with what another person finds, each being merely an expression of rider capability. Experience has to be like with like. Every orbitally geared hub-motor bike I've ridden has been a bit of a pain for me to ride with power switched off for more than a short distance, while I've often ridden for miles on the Panasonic equipped bikes with hardly any more effort than on a normal bike.

That ratio of effort difference will hold good for any other rider, and it's been the often commented on universal experience of those who've ridden both to any extent. And I repeat the important point you've ducked, that's why these hub motor bikes don't have an off switch on the handlebar, it having no possible function for the great majority of riders.

All the Panasonic equipped bikes do, as it's useful enough to be frequently used for range advantage.
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[flecc]

If I understand correctly, the Panasonic system drives the chain. So at the very least, there is still a sprocket rotating when its turned off and the rider is pedalling. It shouldn't be that different in drag to a well engineered hub motor. If they both have a freewheel to disconnect the motor, surely there are broadly equivalent amounts of rotating parts left turning.

Nick

See my comments above on experience Nick. Ride both and the theory instantly disappears, there being no comparison, as all who've ridden both to any extent confirm, and have done so in here many times.

In fact there isn't engineering equivalence, but I won't go into the lengthy explanation of the reasons why that's so.
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[jimmyengland1000]

I used a Heinzmann kit and would not recommend buying one. They are well engineered but very heavy and noisy. The whine from the motor (downside of metal gears as opposed to plastic) is irritating and ruins country rides when all you want to do is ride along quietly. The motor is a brushed motor which will at some point require brushes (Heinzmann said after 10,000 miles but I'm not sure about that) Also, the Heinzmann kit is 100% throttle controlled. The throttle assembly is actually Italian and very bulky. It interfered with the brake lever and gearchange lever on my bike. Because the kit is not pedal controlled in any way, it's easy to use the throttle (and therefore battery power) and not pedal enough. Also, the kit is expensive.

I was very disappointed with my Heinzmann kit. I may be wrong but, to me, it looks like old technology. Big, solid and heavy and no doubt lasting a long time but still old.....

 

[jimmyengland1000]

PS. On my Wisper 905e, I found no resistance at all (that I could detect at any rate) from the motor when pedalling with the power completely off. What kind of motor would that be then? Does it have orbital gears?

 

[flecc]

The Wisper does have orbital gears Jimmy, and they are reported as low drag by others. However, you would still be surprised at the difference to the Panasonic system.

The Heinzmann difference is that it's not a balanced drive system. Orbital geared hub motors normally have three circumferentially equidistant gears between the centre drive gear and the orbital ring, therefore having almost neutral radial thrust, but the Heinzmann has a single gear just ahead of top centre driving the orbital toothed ring in the hub, therefore having an unbalanced thrust present all the time. It also has a fixed motor wall on one side, with the bearings for that at the periphery, an obvious mechanical disadvantage.
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[jimmyengland1000]

Hi Flecc. Could you explain what the effects are of unbalanced thrust please? The Heinzmann motor felt like the drive was cutting in and out all the time, even though the motor was still spinning and it was working fine (if you see what I mean?) Pretty soon, I'll be able to comment on the Panasonic setup in the Agattu!!

 

[flecc]

Because the teeth on a typical gear and it's orbital gear ring are tapered in profile, they form ramps, and when drive thrust is applied, the slope of the ramp of an engaged gear tooth tries to force the teeth out of engagement.

With a one sided driving gear wheel like the Heinzmann, that means the orbital teeth are trying to force the gear wheel away towards the hub centre.

When three slave gearwheels transmit drive from a centre gear wheel to the orbital ring, the thrust is present on both sides of the three orbital gears, so they are held in balance between centre and periphery, hence not suffering the same mechanical losses.

In addition, there are two forms of the Heinzmann drive. On the version we call the 200 watt, the gear is nylon, on all the higher powered versions it's steel. I'm guessing you had the 200 watt motor, and the nylon gear teeth had suffered distortion and wear, this giving uneven drag and drive thrust like that you experienced.

Why nylon? It's by far the quieter on that mainstream consumer model, the noise of steel gears being less important to the performance types who buy the higher powered versions.
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[jimmyengland1000]

Actually, mine was the 500W motor with steel gears. A bad choice on my part, I'd say. Presumably it needs steel gears to cope with the power output. It was very noisy, I thought and the whine came and went, to some degree, depending on the speed of the bike and whether the motor was actually under load.

Please tell me that the Agattu is quiet.... please.... please.....

 

[Ian]

Please tell me that the Agattu is quiet.... please.... please.....

The Panasonic power unit is reputed to be virtually silent, so make sure you have a good bell

 

[john]

freewheel

Thought people might be interested that the Tongxin freewheel comes after the gears so the motor and gears are both disconnected when freewheeling. This makes it almost silent and very low drag.

John

 

[flecc]

Yes, Jimmy, as Ian has said. There's just a very faint whoosh with each pedal thrust as the motor assists, and it's even quieter than the previous Panasonic unit, the component hugging contoured alloy casing probably having less "sound box" resonance than the oblong cavern of the older one.

Pedestrians can generally only detect that sound in a quiet lane. In any sort of urban environment it's lost in the background mush.

The integrated bell is tiny, but has a distinctive high frequency note. Elderly pedestrians might need something louder, though I prefer to merely slow down and avoid them, rather than shock them out of their reverie.
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[prState]

lease tell me that the Agattu is quiet.... please.... please.....

I couldn't think of anything my older panasonic unit sounds like, but the amount of sound is similar to a good motorized wheelchair. You could probably ride it in a library and people would know you're scooting around on something electric, but not be startled.

 

[flecc]

Thought people might be interested that the Tongxin freewheel comes after the gears so the motor and gears are both disconnected when freewheeling. This makes it almost silent and very low drag.

John

Yes, that's an advantage of the roller drive design, the free spinning of which I'd already acknowledged earlier in this discussion.

It's difficult to arrange a peripheral freewheel in an orbital geared drive, leaving the choices as a motor to centre sprocket freewheel, or a spindle to gearwheel cage freewheel. The latter can allow either the orbital gears to track the hub toothed ring, or their gear cage to track the hub and spin it's gears on the motor gear, or everything except the armature rotating, hub, gear cage and motor rotor, in which case there's electrical drag in generation mode.
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[Jeremy]

Flecc, please don't get the hump, all I was doing was making it clear that your very clear and all-embracing statement that:

all hub motor bikes are a pain to pedal without power

(not just those with gears etc) seemed a bit wide of the mark.

I certainly wasn't being at all subjective about describing the case for the gear-less motors, either. In fact I made the clear objective point that this type of motor was little different mechanically from a normal wheel hub.

I think we are actually all in basic agreement here. Some hub motors can add a considerable amount of drag when not powered, just as some bottom bracket drive motors can. There is no intrinsic difference resulting from the layout, just one that results from the implementation of the engineering solution.

Amongst the low drag options are the Panasonic unit, the gear-less hub motors, like the Crystalyte and Goldenmotor, and perhaps one or two of the geared hub motors where there is a free wheel fitted in the best location, like the TongXin/Nano unit perhaps.

Amongst the high drag options are geared hub motors where there is no free wheel fitted, or where one is fitted in a poor location, plus some of the bottom bracket motors that similarly involve the rotation of gears etc when being pedalled.

For someone not familiar with the various options and looking to be able to make an informed choice as to whether or not to buy a ready made bike, or a kit (the whole point of this thread) it is important, I believe, that we all make the effort to be clear that any configuration can be good or bad in this respect.

Jeremy

 

[flecc]

Thanks Jeremy. I refer to hub motors in that fashion, meaning orbitally geared hub motors since they are the overwhelming majority, in just the same way as we say car, and not petrol car. Obviously it's the few exceptions that get the clarification, as in electric car and direct drive hub motor.

I was speaking in the context of the post and answer that was being commented on, so wouldn't have felt clarification necessary anyway, and as you say, in that context we don't have a disagreement.

I wasn't getting the hump over the technicalities though, more the combative nature of postings that this forum seem be turning more to now. On a number of occasions recently after posting a perfectly correct and reasonable answer, I've had to suffer an unnecessary challenge and the dispute that follows, and I don't come in here for that.

I come in to try to help people with my knowledge and experience, and sometimes to give an opinion, and if someone wants to post their opposite experience without reference to or impugning my observation, that's fine, and also desirable. You can see a good example of this on the the "I Can Hardly Believe It" thread where several of us have a differing experience from Doug at Wisper, New Milton and have posted accordingly without comment on Doug's entry.
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[Jeremy]

Flecc, I think the issue is one mainly of the format of a discussion such as this, without the body language cues that reveal the degree of specificity that the writer intends.

I'm a scientist, so do tend to view rather absolute statements as being absolute in their intent, unless they are qualified in some way by the author, hence my taking exception to the damning of "all hub motors", when only a sub-set of this group was the intended target. If I can read your posts as being so absolute, even though this was clearly not your intention, based on your later posts, then I am sure others may well do likewise.

For some of us, a hub motor is either the only practical option, or may be the best option for our requirement. If I had come on here without having some done some research beforehand and asked for advice, knowing that my only option is to fit a hub motor of some type, due to the configuration of my bike, then I would have most probably read your comment apparently condemning all hub motors as being hard to pedal and gone back to driving my car.

The debate here has at least brought the facts out clearly and unequivocally, so that we can hope that there is enough for someone reading this to make a decision based on a reasonably accurate dataset.

Jeremy

 

[flecc]

I understand your point Jeremy, and as an engineer, I also like precision.

But kits aren't my thing, or for the great majority of e-bike buyers for that matter, and with only one direct drive complete bike with limited availability, I tend to ignore the option in posting on e-bikes.

I've recently had a similar difference of opinion with another member who's a journalist, him feeling that what I post on a subject needs simplification and brevity for clarity, effectively the opposite of your position.

There's value in what you both say, but clearly I can't please you both, so I've no doubt I'll be posting in my usual manner in future without indulging in written contortions to cover all the possible interpretations on what I'm posting, or leaving out what I think should be included.

After all, it is my posting.
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[Tiberius]

Well I'm a scientist, who used to be married to a journalist.
You wouldn't believe the arguments we could have, even when we were on the same side.

Nick