So I've got my shiny new hub (just got to sort out the rim and spokes now, as well as work out what to do for a rear wheel). Turning it it sort of 'clicks' (but without making the sound, if that makes sense) - I'm presuming that's normal?
CityCyclingEdinburgh Forum » Questions/Support/Help
Dynamo Hub Question
(19 posts)- Started 11 years ago by Wilmington's Cow
- Latest reply from gembo
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Posted 11 years ago #
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Its normal....
Posted 11 years ago # -
Yes, it's perfectly normal. You won't notice when riding, but you will notice if you spin the wheel up by hand. It's just the inner magnetic witchcraft at work.
Posted 11 years ago # -
What they said^
Also I noticed that when first fitted the wheel felt quite "draggy" and I assumed it was being caused by the dynamo, now it's had a few miles it's much smoother and must've just been the new grease/bearings etc settling in. Just like any other new hub really (doh!)My brain keeps telling me it must create drag, but when I freewheel it floats along in the usual roadbike fashion so I'm sure any "resistance" is purely in my head (badoom tish)
Posted 11 years ago # -
There is very slight drag with dynohubs but it's pretty imperceptible. For example, at 30kph a Schmidt hub requires an extra 1.5W effort from the rider compared to a normal hub - this is with the light switched on, it's considerably less with the light off.
Posted 11 years ago # -
The bearings in the non-lower-end-of-the range Shimano hubs (DN-3N70/80) are the same as found in their Ultegra hubs (according to Peter White's dynamo pages)
I found that when I had the dynamo wheel built, the total weight of the rim and hub was less than the bottom-of-the-range Shimano clunker it replaced, and it felt freer spinning on the road.
According to Peter White, "Energy required of the rider to rotate the hub when the lights are turned off at 30 km/h" is;
Shimano Nexus - 6.5 watts
Shimano DH-3N7/8 series - 2.2 watts
Schmidt SON - 1.5 wattsPosted 11 years ago # -
So the 3N80 is the lower end of the range?? What models are the upper end of the range for Shimano?
I didn't go for the SON as they were over twice as much.
Posted 11 years ago # -
"So the 3N80 is the lower end of the range?? What models are the upper end of the range for Shimano?"
No the 3N80 is the top of the range. The 3N70/71/72 are essentially the same as each other with minor cosmetic differences.
Just don't buy an NX-30 hub as they are draggy.Posted 11 years ago # -
Cheers Martin, I saw 3N70/80 and assumed it was the 80 family Andy was talking about.
Posted 11 years ago # -
The NX- and DH-3N3X numbered Shimano hubs are in the Nexus series, which is the bargain / general purpose range from Shimano.
The DH-3N7X/8X ones are their higher end of the range ones aimed at road and touring. These are the ones based on Ultegra brearings. I think 80 is just a lighter weight 70.
There's a DH-3D series which seem to be for disc brakes.
There's also a DH-T series where I think "T" stands for trecking and are based off of Deore LX components. By the looks of it they are similar to the 70/80 types but they just haven't bothered to lighten them up.
Posted 11 years ago # -
@WC.
Did you get the Disc version? I did and have just taken the dumano hub off the Cotic to be put back on the Dawes for summer Audaxing.
Dave (DH-3D80) C
Posted 11 years ago # -
Nah, non-disc in the end for various reasons.
Posted 11 years ago # -
It's also worth keeping the resistance losses in perspective.
Let's say you had a Nexus hub losing 6.5W at 30kph; the difference between a Continental GP3000 and Vittoria Open Corsa is 20W at the same speed (and these are both racing tyres).
That data's a little stale but see here for source.
Posted 11 years ago # -
So where does the deore xt dynohub fit into all these numbers and letters? :-s
Posted 11 years ago # -
@Kappers, "The DH-3N7X/8X ones are their higher end of the range ones aimed at road and touring. These are the ones based on Ultegra brearings. I think 80 is just a lighter weight 70."
Do you know if the bearings are chagneable on these DH-3D80 dynamo hubs? When I bought the hub I recall reading that the Son hubs were servicable but the Shimano hubs aren't? I'm guessing that this refers to the brushes on the rotor and not the bearings if it suffers from excessive use years down the line?
Cheers, Dave C
Posted 11 years ago # -
Both Shimano and Schmidt advise that their dynohubs are not user-servicable. People have replaced the bearings in Shimano hubs but be very careful - if you break the copper wire whilst bending it you'll most likely need a new hub.
http://dl.dropbox.com/u/3819048/Overhauling%20Shimano%20Dynamo%20Hubs.pdf
Posted 11 years ago # -
Ah right I understand.
Posted 11 years ago # -
In case it's germane to the topic at hand: hub dynamo friction by yours truly
Posted 11 years ago # -
Mr G used to service my nexus 8 hub at EBC But this became verboten, all they are allowed to do now is clean and re-grease it in a wee bath
Posted 11 years ago #
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