Current S-A dynohub (no pun intended)

[fausto99]

Does anyone know if the current Sunrace production dynohubs are much different to old school dynohub. Just idle curiosity, as I avoid cycling in the dark these days.

The parts list diagram shows what looks like the original design size and shape steel pole pieces. The magnet is just listed as a "magnet"; no indication of what the material is. One would have hoped that the whole thing could have been redesigned to be much smaller using neodymium magnets?

[Brucey]

current models (listed on their website) comprise 70mm and 90mm hub brakes, and 3W or 6W generator outputs.

However you may also find 2.4W models (intended for NL market) and a non drum-brake hub generator series eg

https://www.sjscycles.co.uk/dynamos/sturmey-archer-hds12-dynamo-front-hub-silver-36-hole/

which is (or was) also available with a disc brake fitting, in 2.4W form. This has different innards from the drum brake models.

I have used 2.4W and 3W models with the 70mm hub brake and they do what they say on the tin, and are good for those who leave their lights on all the time. However it seems that they also have a fair amount of parasitic drag when the lights are off too. How much? Well, one test (at least a decade ago now) reported comparable levels of drag whether the lights were on or off. They may well have changed things since then; in fact they must have, since they didn't list a 6W model to start with (however I note that only 2.4W and 3W models are mentioned in their pdf documentation).

The HDS series look a lot like they might have sanyo innards in them. None of the recent generators have any similarity to the old SA dynohubs which came out of Nottingham until about 1980.

cheers

[iandusud]

I fitted a 90mm drum brake/dynohub on my cargo bike and I'm very pleased with the performance of the brake and the dynamo. I have the lights on all the time. I would say that for a utility bike they are great and very good value for money.

[ConRAD]

... 6W generator ...

.. interesting, but where did you read about it?

[Brucey]

... 6W generator ...

.. interesting, but where did you read about it?

p8 of the 'current' (2017-2018) catalogue on their website;

https://www.sturmey-archer.com/en/catalogue

never seen one in the flesh, only 2.4W and 3W models. I would be prepared to believe it all is a typo except for the graphs;

graphs from 2017-2018 catalogue

graphs from 2014-2015 catalogue

cheers

[Sid Aluminium]

My NOS 1964 GH6 Dynohub and my 2014 HDS12 Dynohub don't seem to share any DNA beyond operating on the same general principle of all magneto hubs.

[ConRAD]

...

.. and you think that if I call SA ordering a XL-FDD HDS96T 6V*6.0W ... I'll really get a XL-FDD HDS96T 6V*6.0W 90mm Front Drum Brake Dynohub ??
… and what about reported features description ??
- Dynohub in 3.0W and 6.0W (just charts?)
- Integrated 90mm and 70mm drum brakes available (avauilable means that they are an option?)
- CE & EN compliance (no idea which CE or whatsoever EN they might refer to)
- Aluminum hub shells (ok)
- Sealed cartridge bearings (ok)
- Low rolling resistance (!!!???)
- Sealed against weather conditions (!!!???)

[Brucey]

as I mentioned before I have not seen one in the flesh and there is only the catalogue description to go by. If you look in the 'products' section of the SA website there is no mention of the 6W models. Nor do the retailers which normally stock SA hubs seem to list the 6W models. So as to whether you can actually buy one is unknown to me; if you are going to order one I shall be interested to see how you get on.

cheers

[SA_SA_SA]

...
SA hub dynamo 3w 2_4w 2014 2015.png...

Based on those graphs, wouldn't most non-german 100% dyno-LED users be better with the presumably less draggy 2.4w hub?

(The more rigid german rules rigidly specifying 3w or 1.5w(but with aelected lamps) only.)

[Sid Aluminium]

I have no complaints about the way my 2.4W Dynohub energizes my B&M IQ X.

Better than the perhaps more draggy 3W? I'd be 'better' with a SON Deluxe but it was an HDS12 Dynohub that was spoked into my wheel when I upgraded to the IQ X lamp.

[Brucey]

re using a SA 2.4W generator; the 3W Stvzo specification is largely driven by the need to meet a certain percentage of 3W at some low speed (from memory something like 80% at 12kph) when driving a purely resistive load. This is to ensure that even at lowish speeds tungsten bulbs are still reasonably bright, and more visible than dull orange glow-worms.

Fact is that you don't really need this with LED lights because they always make nice white light even at low speeds. Furthermore many cheaper LED lights reach full brightness at LED powers of as little as 1W. Also LED lamps that will use 3W (or more) are usually comparably efficient to lower power lights even when fed with less power. So there is little doubt that a generator that doesn't meet Stvzo may still be more than enough to make pretty good brightness from most lights.

So a SA 2.4W generator reaches 3W output at 25kph and a 3W one reaches 3W at ~16kph. But the 2.4W generator makes 2.5W or more from ~16kph and in reality you would be hard-pushed to tell the difference between that and 3W with most setups.

Note that the test conditions for SA's graphs are not indicated, but I am assuming that this is into a resistive load (because that is how the test is usually done). If the load is reactive (eg containing capacitive or inductive elements) then the power may be more or less vs that indicated by the test data. I think that lots of commercial lamps are slightly reactive loads and are brighter at lower speeds than would otherwise be the case.

Also many dynamo rear lights don't use their full allotted 100mA; as little as 30mA in some cases. This means that you can still have nearly 2.4W for the front light, much as you would with a 3W generator and a 0.6W rear light.

So in summary, a SA 2.4W hub generator is plenty for most front lights/setups.

cheers

[SA_SA_SA]

I wonder why they seem to have dropped the 2.4w variant; the Dutch liked them I thought?

[SA_SA_SA]

I wonder why they seem to have dropped the 2.4w variant; the Dutch liked them I thought?