Message from discussion Dynamo Hubs - any experience?

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From: a...@chiark.greenend.org.uk (Alan Braggins)
Newsgroups: uk.rec.cycling
Subject: Re: Dynamo Hubs - any experience?
Date: 03 Oct 2005 21:39:25 +0100 (BST)
Organization: University of Cambridge, England
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In article <mn.1c797d5a2b10b110.39...@yahoo.co.uk>, Mark \(MSA\) wrote:
>Wow, you guys really are something else!  Great info, and some great 
>links.
>
>I started off thinking rechargeables would provide better light,and be 
>the easier option, then I changed my mind to a B&M S6 bottle.
>
>Now I've read the last few posts, I really think I want a hub (they 
>provide more 'power right?).

They have two advantages: 
i) they are generally more efficient than bottle dynamos, so for the
same amount of light power you have to put in less pedal power
(though they both vary - a Dynotec S6 bottle dynamo will be as efficient
or more so than a cheaper hub dynamo).
ii) they can't slip unless the wheel actually skids, so by using two
lights at high speed (and putting twice as much work in), you can get
twice the light out. Most bottle dynamos can't handle that.
(B&M do do a 12V dynamo and light set (it won't work with standard
dynamo lights), but it costs more than a SON.)


Bottle dynamos have some advantages:
i) if you aren't using them, they have no drag at all, where even
the best hub dynamos have a little. If you hardly ever cycle in the 
dark but want something that's ready whenever you do, a bottle might
be better for that reason.
ii) if you don't mind the lower efficiency, they can be cheaper.
iii) they work on tadpole trikes where fitting a hub dynamo would
be tricky or impossible.


>So, back to the hub dynamo.  I 'think' for now I will buy a Shimano, 
>run it for a while and see how I get on.  Is the drag and the 'output 
>of the Shimano similar to the SON 28, or would I be losing out?
>Keeping the price lower if possible (if it's false economy then please 
>tell me) which Shimano hub should I go for?

How much you lose out depends which Shimano hub you go for.
IIRC Sheldon stopped selling the SON because he thought the DH-3N70
was very nearly as good for quite a lot less money. (The earliest
Shaimano hubs weren't as good.)
I've never seen a SON owner wishing they hadn't spent the extra money,
but nor have I seen a Shimano owner wishing they had.

If you like knowing you have the very best regardless of cost, go for 
the SON. Otherwise I suspect the higher end Shimano would be fine.
(The low end Shimanos aren't _bad_, but if you are prepared to even
consider a SON, you probably want the better ones.)