hub dynamo question

Simon Brooke wrote:
On 5 Aug, 00:10, "Adam Lea" wrote:
I am toying with the idea of getting a hub dynamo for the coming winter,
however the wheels on my road bike only have 20 spokes which is less than
more conventional wheels which I understand have 32 or 36 spokes. Are there
any hub dynamos that would be compatible with my wheels?

Are these conventional spokes?
I have seen low spoke count wheels with special hubs and spokes, in
which case a rebuild would not be an option.

Also, how easy would it be to install the dynamo myself, given that the
spokes go straight out from the hub to the rim? It looks as though it should
be easier than rebuilding a conventional wheel but there may be something I
have missed (I have never tried wheelbuilding before).

Radial spoking cannot be used to transmit torque from the hub to the
rim - which is why you never see it on rear wheels or dick braked
wheels.

Ouch. I have used my hands before when the bike is in the stand but....


The torque required for a hub dynamo is much smaller of
course, but radial spoking is still not recommended. You need to go at
least one cross; having seen Ian's analysis of spoking, I'm not
convinced you need to go two cross.

I too am planning to build myself a dynohub wheel for this winter,
probably using a SON S20R (Yes, I know it's three times the price of a
perfectly good Shimano part). I'll be lacing two cross on a DTSwiss
R1.1 rim. I already have a pair of home made wheels with Record hubs
and DTSwiss R1.1 rims, so this will be the winter/expedition front for
that wheelset. There's nothing specially difficult in lacing wheels
anyway - all it takes is care and patience

and sheldon's guide to wheel building.

- and the dynohub, being
relatively large, should be easier than a smaller hub.

TBH there is not much difference. Although my dynohub was the first
wheel I built.

What I'm saying, in essence, is keep your existing front as a summer
wheel, and build yourself a whole new wheel.

Yes I agree there.

On Wed, 05 Aug 2009 10:39:03 GMT, _
wrote:

On Wed, 5 Aug 2009 00:33:14 -0700 (PDT), Simon Brooke wrote:

Radial spoking cannot be used to transmit torque from the hub to the
rim - which is why you never see it on rear wheels or dick braked
wheels.

Not strictly true, assuming you mean the common definition of radial
spoking. The out is that wheels which at rest are spoked radially, have
hubs and spokes which, when torque is applied, "wind up"; which changes
them from radial to being at a very slight angle, and then then transmit
torque through tension, as do wheels spoked in more tangential patterns.

It's not that wheels spoked in this manner cannot transmit torque; it is
rather that to relaibly use ant common hub in this fashion risks flange
breakage.


Come on - own up - who has lifted up the stone?


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