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Message from discussion Dynamo Hubs - any experience?
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Alan Braggins  
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 More options 4 Oct 2005, 08:08
Newsgroups: uk.rec.cycling
From: a...@chiark.greenend.org.uk (Alan Braggins)
Date: 04 Oct 2005 08:08:41 +0100 (BST)
Local: Tues 4 Oct 2005 08:08
Subject: Re: Dynamo Hubs - any experience?
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In article <437387e2.500247...@n.nabendynamo.de>, Andreas Oehler wrote:
>Mon, 3 Oct 2005 21:00:55 +0200, James Thomson:

>>"Alan Braggins" <a...@chiark.greenend.org.uk> wrote:

>>> Roseversand don't seem to have the new DH-3D71, only the 70.

>>http://cycle.shimano-eu.com/publish/content/cycle/seh/nl/en/news___in...

>>Ah, I wasn't aware of the existence of the DH-3D71.

>Forget about the difference between DH-3N70/3D70 and DH-3N71/3D71.
>Measurements by me and other people showed no substential difference in
>drag between both types. The only difference is a little more electrical
>power of the 71's at slow to medium speed.

I suspected Shimano's claims were exaggerated or misleading, but it's good
to hear actual measurements. Thanks. (But as someone who often travels
at a slow to medium speed, I might bother to go for the 71 anyway.)

>>S>resistance and the result is amazing: They have a 40 % lower rotation
>>S>friction than the current models (DH-3D70, DH-3N70 and DH-2N70) and

>The amount of mechanical *friction* is relative low.

[...]

>>S>even 75 % less resistance than previous models when the lamp is turned off!

>This is true (whithin measurement accuracy). The HB-NX32 takes up about
>8-9 Watt at 30 kmph when switched off.
>The SON28 has a no-load drag of around 1.5 Watt at 30 kmph.

I'd interpreted "previous models" as meaning the 70 range from the previous
sentence. I knew there was an earlier Shimano one that actually had more
drag when turned off at high speed. (I don't know the model number,
http://www.myra-simon.com/bike/dynotest.html says "Inter-L", but you
probably do.)

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