Non-drag hub motors
- Thread starter eHomer
- Start date
Yes indeed, as a ride on a recumbent soon shows !
I think my opening post/question on this thread is being misunderstood by some of the repliers.
Now that I've built two reasonably lightweight electric bikes, I like to do some sections under human power alone, to increase range, and then only engage electric assistance on the hilly bits.
The 250watt geared motor has no drag at all, at any speed, because of the geared freewheel, but it makes the milk float noises because of the fat bloke sitting in the saddle.
The 1000watt direct motor is much quieter, but the drag when pedaling it with the motor switched off is quite significant, at any speed, like a steady continuous upward gradient.
I'm talking below significant wind resistance speeds here, around 12 to 15 mph.
Dave's pure sinewave controller sounds well worth trying, to cut down the "straining" noises. I can understand the theory of the pulses being less abrupt, and the reduction in the electrical noise from the motor, especially under torque when pulling away.
Or just ride faster ... you can't hear whether a motor is making any noise at >18mph because the wind noise drowns it out. My headphones plugged in to my smartphone music player on the handlebars do the same 
If I'm tootling along at 12mph and don't want to be heard I just pedal harder ... can't hear a thing
If I'm tootling along at 12mph and don't want to be heard I just pedal harder ... can't hear a thing
D
Deleted member 4366
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The proof of the pudding is in the eating. Andrew and myself both tried one on the same motor as his bikes now use. The result is a quieter geared motor. We'll only know about the theoretical efficiency advantage in a long-term test.
Hub motors don't have a lot going for them in my opinion. They can't break or recuperate very well and without power they become a anchor around you neck. One of the most important parts of a bicycle is the wheel set, so if they are to survive as a product for people planing on traveling on the other side of 25 Km/h, they have to simulate a decent wheel. That means using power after 25 Km/h. So if I where to manufacture a hub motor, I would use light nimble wheel as my baseline. The goal would be not to be able to distinguish the two wheels from each other seen from a power perspective. Of cause that would require the use of power over 25 Km/h, which some would say is illegal. But how can that be, when I can buy a bike with a Bosch center motor and put a pair of descent wheels on it and get the same result ?
Yes
If one is not used to riding a bike, then of cause you are going to be surprised when the motor cuts out. But if you know what you are doing, then there is no surprise. And I can clearly feel the difference between a hub motor and a £100 wheel set like for instance fulcrum racing 7. And the difference is not tiny, but major wind or not.
I assume you mean Andrew from Oxygen and the Dapu geared hub motor with 85% efficiency that can be easily de-restricted through the handlebar controller to 40kph.
They do a quieter version by changing the ratios?
"Reduce the noise to the minimum level by adopting the gear with 1.25 module."
http://www.dapush.cn/English/Product_1.htm
Do either of you have any published official noise level figures so we can compare the difference?
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At the risk of going where you don't want to, have you considered a crank drive? you can use the worlds best wheels and keep the Quick releases, you will be able to freewheel with zero extra drag and nothing noticeable when pedaling.
Noise wise mine is audible but certainly not intrusively so.
Noise wise mine is audible but certainly not intrusively so.
Yes one can, but the price is too high in my opinion, if you plan on spending most of the time over 25 Km/h.
Me yes with the knowledge I have now. The only reason I bought a bike with a hub motor was because I didn't try one, but only looked at a pretty picture. If you mean eHomer, then he has a recumbent and I haven't seen one of those with a nose motor. If ever there was a bike that could use a e-motor, it is a recumbent and I can understand that eHomer is annoyed. There you are spending a lot of time to get out of the wind only to have the advantage gobbled up by the hub motor.
Yes, they're still a possibility for me.
I tried a Cyclone 24 volt 350 watt a few years ago when they first came out.
I didn't think it out very well though. because I fitted it to a Dahon folder with 20" wheels, so the crankset with 44 teeth was too small to run the 5 speed dérailleur gear at anything faster than about 12mph, by pedaling or motor. It would have needed over 50 teeth, and there wasn't room.
I see there's quite a few choices now, and they do make sense, using the bikes gears.
I've noticed the new crank drive being discussed on here.
The ideal of a really simple direct drive hub motor, with no touching wearing parts (other than the bearings) is really attractive still, though the penalty of the drag is a show stopper for me.
Decisions, decisions... "I used to be indecisive, but now I'm not so sure"...
Yes I know what you mean, even my Tongxin reduces the top speed of my racing trike on long shallow down hills.Yes, they're still a possibility for me.
I tried a Cyclone 24 volt 350 watt a few years ago when they first came out.
I didn't think it out very well though. because I fitted it to a Dahon folder with 20" wheels, so the crankset with 44 teeth was too small to run the 5 speed dérailleur gear at anything faster than about 12mph, by pedaling or motor. It would have needed over 50 teeth, and there wasn't room.
I see there's quite a few choices now, and they do make sense, using the bikes gears.
I've noticed the new crank drive being discussed on here.
The ideal of a really simple direct drive hub motor, with no touching wearing parts (other than the bearings) is really attractive still, though the penalty of the drag is a show stopper for me.
Decisions, decisions... "I used to be indecisive, but now I'm not so sure"...
D
Deleted member 4366
Guest
Andrew has already changed to Dapu motors. The one we tried was a normal production one like he uses on his bikes. you can't change the ratios. The gears in each motor are fixed for that type, although there's big and small motors that probably have different ratios from each other. You can often get different speed motors of the same type because they have different coil-windings - nothing to do with gear-ratios. I don't know the winding speed of the Oxygen bikes' motors. I guess the same as the previous motors at about 270rpm.
The noise of geared hub-motors (IMHO) comes partly from the design of the motor, but mainly from the controller. You can change controllers and often get a different noise level.
The main noise factor for normal hub motors is related to the amount of current you run. You can see/hear it by using high or low throttle. If you solder your shunt to get more current, you can hear the increase in noise.
The speed you set on the panel has nothing to do with noise. It doesn't affect current in any way, but the faster you go, the less current you get, so the motor will be quieter the faster you go. I don't know if the new Oxygen bikes will be able to reach 24mph like the old ones. It depends on the winding speed of the motor, but I think it was the same when we setup Geoff9's new Oxydrive kit. I know you can adjust the speed limit, like the old one, because we tried it on Geoff's.
The sine-wave controllers I'm getting are for my own bikes - nothing to do with Oxygen. In case you're implying that my mention of them was for commercial reasons, your completely wrong. I only want to try them in the quest for shared knowledge, and I'll publish the results here for the benefit of everyone.
The motor you linked to is a direct drive motor. The ratios are the assist level - nothing to do with gears.
As a general point, I could see that hub-motor technology is moving on all the time. Many now have the spline for cassette gears. I was also shown computer models of one with its own internal 2-speed gearbox. My own opinion is that some hub-motors are better than all the currently available crank-drives. The control systems that most commercially available hub-motored bikes use are fairly rudimentary and could be improved a lot to give much better comfort and dynamics, while as some of the crank-drives have much more sophisticated systems. People should keep an open mind about which type of motor is best and think about the overall system and it's characteristics, and not just try and compare one characteristic to pronounce judgement.
I completely agree with Dave on the hub motor noise cause, it is primarily electrically inspired and current related. That's why it decreases with increasing revs, if the noise was gear related, it would increase with revs as the number of tooth meshes increased.
Sine wave controllers should bring a real noise reduction to any given motor system and could increase reliability as a side benefit.
Sine wave controllers should bring a real noise reduction to any given motor system and could increase reliability as a side benefit.
I would agree with your statement if the motor was unloaded but in the real use gear/bearing noise is self evident.
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