Dynamo hubs - service

[Sepia]

Hi All

I have a Supernova Dynamo hub and I think it is not o'k?

The axel is so tight that it cannot be turned by hand when spinning the wheel. It only turns if you hold onto the skewer.  Surely this is not right? Is this normal?

 

I have taken it to my local LBS and I am asked what is the matter with it?

Does anybody have advice on this, please?

Expensive piece of kit and I don't want to inflict any more damage by using it as is.

Appreciate any help on this.

Thanks

[Simon Kolin]

That definitely sounds like something is seriously wrong with the hub.

 

That said, I don’t have any experience with dynamo hubs.

 

Get hold of Nick the Wheelbuilder and get his opinion. He builds occasionally with dynamo hubs, and could possibly help out.

 

https://www.bikehub.co.za/user/72928-nick-the-wheelbuilder/

[Sepia]

That definitely sounds like something is seriously wrong with the hub.

 

That said, I don’t have any experience with dynamo hubs.

 

Get hold of Nick the Wheelbuilder and get his opinion. He builds occasionally with dynamo hubs, and could possibly help out.

 

https://www.bikehub.co.za/user/72928-nick-the-wheelbuilder/

Thanks Simon, I am seriously thinking of sending this inland for inspection.

Can't believe there is not a decent enough wheel guy in Durban.

[Grantc]

Graham Bates in Jhb is the guy you want

[Sepia]

Graham Bates in Jhb is the guy you want

He did my electrics.  Did not know he does wheels? It is the hub itself and not the dynamo?

[Simon Kolin]

Thanks Simon, I am seriously thinking of sending this inland for inspection.

Can't believe there is not a decent enough wheel guy in Durban.

Not even Leigh's Cycle Centre?

[Sepia]

Not even Leigh's Cycle Centre?

Was never a fan of Leigh's when they were at the Pavilion. Got a bad deal there more than once.

But, if they know what they are doing, it may be the time for forgiveness.  I would need to talk to them about the hub first to understand that they understand.

Paul at Melville Cycles also comes to mind as an option.

[Simon Kolin]

Ok. See what joy you can get Leigh's and maybe try Paul.

 

I still recommend that you reach out to Nick the Wheelbuilder for an opinion.

[Brakepad]

I have seen lots of dynamos hubs and serviced them back in Europe. You can not turn the axle due to the magnets and stuff , if you turn the wheel without a tyre while holding it by the axle it feels slightly rough (very rough on the cheapies) if you do the same with a tyre you should not feel any imbalance(maybe at very low speed) and if you ride it you should not feel any different to a normal hub.

So if there is anything wrong with the bearings you can not feel it , maybe hear it or see it when taking it appart

[Sepia]

I have seen lots of dynamos hubs and serviced them back in Europe. You can not turn the axle due to the magnets and stuff , if you turn the wheel without a tyre while holding it by the axle it feels slightly rough (very rough on the cheapies) if you do the same with a tyre you should not feel any imbalance(maybe at very low speed) and if you ride it you should not feel any different to a normal hub.

So if there is anything wrong with the bearings you can not feel it , maybe hear it or see it when taking it appart

Yes, thanks. This is the issue. I understand there is a bit of "roughness" due to the innards but it is almost impossible to turn by hand while holding it.  Is this not too tight?  I understand that spinning the wheel on the bike this will not be felt but am I doing any damage if it is so tight?

Thanks for your informed advice    

[Brakepad]

Just found this on the web about a SON Dynamo:

 

When you hold the wheel or hub in your hand and turn the axle, you'll feel a lot of resistance. There are 26 poles and 26 magnets in the SON28 hub (fewer in the SONdelux). That creates 26 points around the hub shell that the axle wants to settle in, and a corresponding 26 points where the axle doesn't want to be. In the transitions between those points, the axle wants to turn in one direction or the other, to find the point where it wants to settle. As you ride, the hub turns relative to the axle, and 26 times in each rotation of the wheel, the hub wants to turn one way, and then the other, theoretically speeding you up and slowing you down, 26 times per rotation. At speed, the effects of these two forces almost completely cancel each other out, leaving you with extremely low drag overall. It's only when you don't have a lot of mass (your weight) and inertia (your speed) that the effect is to actually retard the rotation of the hub axle. So there's no reason to be concerned about the way the axle feels when turned by hand.

[Sepia]

Just found this on the web about a SON Dynamo:

 

When you hold the wheel or hub in your hand and turn the axle, you'll feel a lot of resistance. There are 26 poles and 26 magnets in the SON28 hub (fewer in the SONdelux). That creates 26 points around the hub shell that the axle wants to settle in, and a corresponding 26 points where the axle doesn't want to be. In the transitions between those points, the axle wants to turn in one direction or the other, to find the point where it wants to settle. As you ride, the hub turns relative to the axle, and 26 times in each rotation of the wheel, the hub wants to turn one way, and then the other, theoretically speeding you up and slowing you down, 26 times per rotation. At speed, the effects of these two forces almost completely cancel each other out, leaving you with extremely low drag overall. It's only when you don't have a lot of mass (your weight) and inertia (your speed) that the effect is to actually retard the rotation of the hub axle. So there's no reason to be concerned about the way the axle feels when turned by hand.

Good man!  I have checked the internet but could not find this.  Appreciate it very much.

Grateful  thanks!

[Simon Kolin]

Just remember, that you should be able to turn it by hand. Even if it's only barley. From what I understood from your OP you can't even do that.

 

Have I misunderstood?

[BikeisLife]

Thanks Simon, I am seriously thinking of sending this inland for inspection.

Can't believe there is not a decent enough wheel guy in Durban.

Rowan Johns at Bike Works in Winston Park.

 

Great service and always willing to help.

[EddieV]

Hi Sepia

 

I have 3 SP hubs, I think your Supernova is a licensed version of the SP (Shutter Precision), but I might be incorrect.

I’ve imported and laced them myself. Out the box, before lacing I found them incredibly hard to turn by hand, but on the bike after lacing to the rim the spin easier.

Sadly the SP dynamo hubs are not user serviceable and they have to be sent back to the manufacturer for services ... thus I doubt you’ll find someone in SA to service it.

I have also decided to rather import the SON hub for my next build, which is user serviceable.

If you do find someone to service it locally, please let me know, I need a bearing replaced on one of the hubs. Was planning on opening and replacing it myself ...

[Sepia]

Just remember, that you should be able to turn it by hand. Even if it's only barley. From what I understood from your OP you can't even do that.

 

Have I misunderstood?

Only with extreme force and then you can feel the "bearings" click which is correct.  Just the effort required worries me.