Which low-end Shimano dynohub?

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KEELIEDW
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Joined: 21 Jan 2007, 2:01pm

Which low-end Shimano dynohub?

Postby KEELIEDW » 1 Dec 2016, 10:43am

I'm about to order a cheap 700c dynohub wheel from Taylorwheels.de for a utility bike. Wheels in the £30-£40 range use either the DH C3000 3N or the DH 3N 31. Anyone know if there's any real difference? I'm particularly concerned about drag when switched off.

pete75
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Joined: 24 Jul 2007, 2:37pm

Re: Which low-end Shimano dynohub?

Postby pete75 » 1 Dec 2016, 11:33am

Have a DH31 on a couple of bikes. One 700C and no noticeable difference in lights off drag to dh72 or Son 28 I have on other bikes.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Which low-end Shimano dynohub?

Postby Brucey » 1 Dec 2016, 12:00pm

I think you need to be careful when comparing 'lights off drag' by (say) spinning the wheel an allowing to come to rest.

1) If you have a heavier tyre and rim, this will (more or less pro-rata) increase the time it takes for the wheel to slow down.

2) Bearing adjustment can affect the drag significantly.

3) How the hub is lubricated can affect the drag significantly, in part because of seal drag.

To my great surprise I recently found that 2) and 3) changed the lights off drag by about 1W on a brand new shimano hub, i.e. it about halved once I'd set things up nicely. That was on DH-3N72.

I think the sport series hubs (DH-3N72, DH-3N80, Alfine, XT etc) are better than the cheaper models but there isn't much in it. A small difference in drag, a larger difference in weight.

I don't have any direct experience of the C3000 model, but the EV techdoc

http://si.shimano.com/php/download.php?file=pdf/ev/EV-DH-C3000-3N-4024.pdf

makes it look very similar to the old DH-3N31 and indeed many of the parts are 'A' grade compatible with that and several other models.

cheers
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gaz
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Location: Kent, car park of England

Re: Which low-end Shimano dynohub?

Postby gaz » 1 Dec 2016, 12:24pm

For the last twelve months or so I've been toying with the idea of hub dynamo powered lighting. On 20 October I finally ordered a wheel built around a DH-3N31 from Taylor Wheels.

Whatever drag there may be from that hub it is entirely lost in the noise of other "performance" factors associated with my commuter, e.g. mudguard drag, 700 x 28/32 Marathon+, the weight of two D-locks for parking up and the rough canal towpath that is the bulk of my route (when the temperature drops further I'll switch to studded tyres).

A small part of me still wonders if I should have invested another £30 in a DH-3N72 but it would have been with a no-name rim from an unknown supplier.

I am certainly quite happy with what I have and wish I'd gone over to hub dynamo powered lighting years ago. Sometime in the next twelve months I might even add a rear lamp to the system :wink: .
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[XAP]Bob
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Re: Which low-end Shimano dynohub?

Postby [XAP]Bob » 4 Dec 2016, 9:59am

They are all pretty good, and the drag is pretty negligible compared with a few psi in, or out of, the tyres.

The rear light is always good. Knowing you have lights on at all times is very nice...
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