Hub Dynamo Connections

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hjd10
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Re: Hub Dynamo Connections

Postby hjd10 » 17 Oct 2017, 2:39pm

Mick F wrote:All good wisdom there.

I've actually made a neat job of mine using short lengths of heat shrink to tidy it up. It also gives a bit of strength to the wires.
I extended the cable and used co-ax. Neater than the original twin, and if I'd have had the confidence of pulling the light apart, I'd have run the whole length in co-ax.

I still think the whole thing is a bit Heat Robinson. Proper connectors are what's required. TBH, I'm a bit dismayed about having bent wires pushed through as the connection, but hopefully I won't have to touch them very often. Yes, a neat inline connector would be good rather than touching the hub connector again.IMG_0242.JPG


Mick,
I have a question regarding the dynamo. I believe that the one you have is essentially a copy of my Supernova, I've noticed that the electrical connector seems to rotate anitclockwise slightly during a ride. So during a long ride it might rotate a quarter of a turn, have you or anyone else noticed this effect with your SP hubs?
Maybe it is some sort of procession from my disc brake?

Regards,
Last edited by hjd10 on 17 Oct 2017, 8:51pm, edited 1 time in total.

Brucey
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Re: Hub Dynamo Connections

Postby Brucey » 17 Oct 2017, 2:46pm

I suspect that your QR isn't tight enough and/or the axle is a slightly loose fit in the LH dropout. What tends to happen is that the axle gets pulled downwards and backwards in the dropout slot by the brake action. Then the axle may move back again but it may not pivot about the exact same spot. The result is a slow rotation of the axle, which you will notice with a generator hub but maybe not otherwise.

If you have a QR with an external cam, change it for something else.

cheers
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hjd10
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Re: Hub Dynamo Connections

Postby hjd10 » 17 Oct 2017, 3:06pm

Brucey wrote:I suspect that your QR isn't tight enough and/or the axle is a slightly loose fit in the LH dropout. What tends to happen is that the axle gets pulled downwards and backwards in the dropout slot by the brake action. Then the axle may move back again but it may not pivot about the exact same spot. The result is a slow rotation of the axle, which you will notice with a generator hub but maybe not otherwise.

If you have a QR with an external cam, change it for something else.

cheers


Cheers Brucey,
What would you recommend? I've tightened it up now and will look at what happens on the next ride.

Howie

Brucey
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Re: Hub Dynamo Connections

Postby Brucey » 17 Oct 2017, 3:19pm

best options are (I think) internal cam QR (eg shimano) or security skewer, that you tighten like a bolt.

cheers
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Mick F
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Re: Hub Dynamo Connections

Postby Mick F » 17 Oct 2017, 6:35pm

Mine hasn't moved at all despite using an external cam QR.
Mick F. Cornwall

andrew_s
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Re: Hub Dynamo Connections

Postby andrew_s » 17 Oct 2017, 6:42pm

There will be less force on the axle with a smaller wheel,
so the external cam QR may grip strongly enough (the slip force is the braking force times the ratio between wheel size and disc size).

Incidentally, the Supernova hubs are made by SP.

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Mick F
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Re: Hub Dynamo Connections

Postby Mick F » 17 Oct 2017, 6:55pm

andrew_s wrote:There will be less force on the axle with a smaller wheel.
I can see that, but it's going round much faster.
You could be right though.
Mick F. Cornwall

hjd10
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Re: Hub Dynamo Connections

Postby hjd10 » 17 Oct 2017, 8:58pm

Thanks for the update gents...

Brucey
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Re: Hub Dynamo Connections

Postby Brucey » 17 Oct 2017, 10:34pm

Mick F wrote:Mine hasn't moved at all despite using an external cam QR.


doesn't have a disc brake that tries to tear the wheel out of the dropouts the wrong way, either....

cheers
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hjd10
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Re: Hub Dynamo Connections

Postby hjd10 » 17 Oct 2017, 11:06pm

Brucey wrote:
Mick F wrote:Mine hasn't moved at all despite using an external cam QR.


doesn't have a disc brake that tries to tear the wheel out of the dropouts the wrong way, either....

cheers


Probably not helped by a 100kg rider. :(

mfpnl
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Re: Hub Dynamo Connections

Postby mfpnl » 18 Oct 2017, 9:10am

Hi Mick

I used the method described by Brucey on our two Airminals. I must admit, it did take me a while to figure out the 'fold back' bit.

I too was a bit sceptical about the robustness of this arrangement - but it did survive our LEJOG, which I suppose is a reasonable test.

Mike

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Mick F
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Re: Hub Dynamo Connections

Postby Mick F » 18 Oct 2017, 9:31am

Mine seems fine, but it's not been used much or removed much at all.
It does worry me that when cleaning the Moulton - maybe weekly or more - I tend to remove the wheels.

Until you've owned a Moulton, you will never understand how manky they get even with mudguards!
There's many many nooks and crannies that get caked in road muck when it's wet out there.

As for the connector, I'm considering in using soldered braided wire inside and then soldered to the main cable. It can all be hidden and sealed as it enters the plug and the business end would make a better and tougher connection. Just the thin wires soldered and bent over will eventually snap. It may take some time, but if you disconnect and reconnect weekly, I reckon it would only last a year or so.

I'm giving it thought.

In the the next day or so, my new rear dynamo light should arrive from Bike24 plus the various connectors from eBay. When I get all this lot together, I'll be doing a complete wiring job.

One thing I asked earlier, is how do you connect a USB-werk or a Velocharger to the system?
It seems to me, that there needs to be some sort of junction fed off from the dynamo before it gets to the front light.
Not bought one of those yet ....... and I may not buy one .......... but I would like to know what the conventional method is.
Mick F. Cornwall

tod28
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Re: Hub Dynamo Connections

Postby tod28 » 18 Oct 2017, 11:01am

May I point you to the Igaro review https://yacf.co.uk/forum/index.php?topic=100575.0 on yacf which includes discussion and examples for connecting a power supply and light.

Brucey
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Re: Hub Dynamo Connections

Postby Brucey » 18 Oct 2017, 11:25am

eventually the wires in the fold-over plug (which you should definitely not solder!) will wear but it does take a long time.

For comparison, think of how a scalextric car works; provided the track itself is nice and smooth, you can drive whole real (i.e. non-scale) kilometres without the copper braids wearing greatly, and those contacts are not only sliding but also conducting electricity at the same time, so might be prone to wear by arcing etc. This sort of distance would be the equivalent of many hundreds or perhaps even thousands of disconnections of a dynamo plug. IME corrosion is the real enemy, not wear. (BTW If you solder the wires you will lose the springiness and squashiness that makes a secure connection, plus you will run more of a risk that you will get a bad connection via fretting. Solder is not good for mechanical connections that are liable to move.)

If you are really worried about it, leave a little slack in the wires (a good idea anyway) so that they may be bared again and the connection remade if necessary.

The conventional way of mounting an accessory to the dynamo feed is to splice the wires into the wire from the dynamo, e.g. using solder and heat shrink, (pref of the type with built-in glue to help sealing). On most bikes this is done near the fork crown simply because it avoids running two wires down the fork leg. It is quite important to make sure that this connection is waterproof/corrosionproof, since water may run down the wires and into it otherwise; flux residues are liable to help corrode the wires if they get damp.

If you choose to use any form of in-line connector, this introduces many more connections that might go wrong, and this connector itself weighs a lot more than a length of wire does. This means that, unless well-restrained, it will tend to flap around (which may rattle and drive you nuts BTW) and more importantly it is exactly the kind of thing that frets the contacts inside and causes the wires to fatigue prematurely etc. For these reasons (amongst others) inline connectors are normally studiously avoided in wiring harnesses that are subject to vibration.

When I first saw the fold-over plug I had my doubts about it too. If I were going to revise it, I'd make it more like a connection scheme I know works, is reliable, and can easily be remade too. On my old dynohub (which went for about 25 years like this BTW, stored outside in the rain) I modified crimp terminals so that the wire receptacles became sockets (with open ends to drain rainwater) and mounted these semi-permanently to the hub. I used long blade type crimp connectors on the wires (of the sort that are normally used to connect to connections with grub screw-type terminals). The long blades were simply folded double and fettled until they were a snug fit in the receptacle.

The folded blades were slightly springy (by an amount that could be adjusted if required), and the square shape made contact on the corners inside the (round) receptacle, with a low insertion force. This was in such a way as simply pulling the blade out of the receptacle provided a good cleaning action. WIth a smear of waxoyl this connection was quite reliable and proof against corrosion. The idea was that the wires could be easily disconnected by hand, and in fact the wheel could drop out and the connections would automatically disconnect. I think I adjusted the spring action of the blades once a decade or so, and of course the wheel came out many times in that period. In the event of a crimp joint to the blade failing (which in fact they never did), it would be a simple question of baring the wire and temporarily stuffing it directly into the receptacle, perhaps with the unfolded blade (or something similar) as a wedge if necessary. I never had cause to remake the connections in that way, but I would suppose it would be easy enough to do.

So if I were to modify a modern hub generator's connections, I'd probably solder (open ended) cylindrical receptacles to the hub and use similar (eg folded blade) connections into them. But I have not bothered to do this, because the plug that I initially had doubts about turns out to be very serviceable.

cheers
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Mick F
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Re: Hub Dynamo Connections

Postby Mick F » 18 Oct 2017, 4:05pm

They come already soldered!
Thanks for the Scalextric analogy. That makes a great deal of sense, but the plug itself needs a braided wire not the thin core that it is.

Anyway, there's been a development this afternoon.
My connectors arrived in the post, so I set about having a tinker.

Then I noticed that the switch on the back of the light was lying on the floor. :oops: There was a tiny bit of plastic with it too. The switch was always a little tight-feeling. It's supposed to slide through the three positions On Auto Off so must have given up the ghost. Probable U/S originally, but I wasn't to know.

Anyroad up, I had an online chat with Athlete Shop, and explained the problem, and they're sending me another one. Should arrive on the 24th. Meanwhile, they say to keep the defective one ............. so I will! You never know, I could fix it somehow or another.

Off down the pub shortly for a beer or three to drown my sorrows.
Mick F. Cornwall