Hub motor wires through axle, or not?

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reikiman's picture
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Have a question based on a new electric bicycle product I saw yesterday ...

All the hub motors I've seen had wires exiting through the axle. I've never stopped to question this, it's just the way it's been.

Obviously the wires have to interface with the motor at a spot which is still or else the wires would rotate and break.

Is it necessary for the wires to interface through the axle? Or would it be better if the wires could interface through another spot, not the axle? e.g. if the side of the hub motor were still the wires could interface there? And, yes, I've seen such a motor and am wondering what might be the advantage.

Maybe it would make the axle stronger but I've never heard of a case where the axle broke due to it being hollow.

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dogman's picture
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Re: Hub motor wires through axle, or not?

The motor I've seen like that is the Heinzmann, from the EVG bikes. It's wires actually do come out through the axle, but the axle is over an inch in diameter at that point, and then is machined down to the usual size for the bolt. The wires then don't have to get so close to the dropout, and the whole thing has a built in torque arm preventing spinout. A great design and no doubt patented but I'd sure like to see it done similar on big 5305 clyte motors. The larger axle where it meets the cover needs a larger bearing, but it looks to me like it wouldn't add so much to the cost to have all motors done like that. That wire out the end of the axle is a lame solution to me. WE's way, with a notch in the axle is not much better.

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Drunkskunk's picture
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Re: Hub motor wires through axle, or not?

The most logical and strongest design is to have a bearing on either side of the wheel spread out as far as they can be, Supporting the hub on both sides to distribute the load evenly and make the hub as strong as possable. That means to get the wire inside to the non spinning parts, they must go through the center (non spinning part) of the bearing.

Those motors that appear to have the wiring going through the side cover are either going through the center of a realy big (and also expensive) bearing, or are going into a motor that is supporting the hub on only one side.

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Re: Hub motor wires through axle, or not?

is this the new product u saw?
http://www.epluselectricbike.com/E+_Electric_Bike_Kit_Components.asp

the axle is hollow & attached via QR.
no other hub motor offers the same convenience.
a lifesaver anytime u get a puncture.
particularly in a dodgy neighbourhood.

reikiman's picture
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Re: Hub motor wires through axle, or not?

No, that's not it. The motor I saw isn't on the market yet and I'm due to, in a couple ways, have a chance for a long term test period with it. Once I get it I'll be able to say more.

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- EVT 4000, Charger bike (rebuilt), Vego 600sx (rebuilt), Electrified Electra Townie
- Lectra motorcycle, 1971 Karmann Ghia

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Re: Hub motor wires through axle, or not?

i'm intrigued & eagerly await your review.
if it's got that basic part of it right, then i want to see what else it's got going for it.

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