Hub Dynamo for winter commute.

For discussions about bikes and equipment.
zenitb
Posts: 322
Joined: 7 Aug 2018, 9:59pm
Contact:

Re: Hub Dynamo for winter commute.

Postby zenitb » 6 Jan 2020, 8:01pm

niggle wrote:Just discovered a new offering from Shimano claiming up to 44% reduction in dynamo drag: https://www.spacycles.co.uk/m2b0s133p43 ... H-UR700-3D

good spot niggle..looks v.interesting..

dim
Posts: 330
Joined: 12 May 2019, 5:59pm

Re: Hub Dynamo for winter commute.

Postby dim » 6 Jan 2020, 8:05pm

zenitb wrote:
niggle wrote:Just discovered a new offering from Shimano claiming up to 44% reduction in dynamo drag: https://www.spacycles.co.uk/m2b0s133p43 ... H-UR700-3D

good spot niggle..looks v.interesting..


but it produces 3W .... you need 5W so pay the extra and get the Son 28 ... thats what I did, and it comes with a 5 year guarantee

Brucey
Posts: 36851
Joined: 4 Jan 2012, 6:25pm

Re: Hub Dynamo for winter commute.

Postby Brucey » 6 Jan 2020, 8:49pm

most '3W' generators will produce quite a bit more than 3W; this depends on the load as much as the generator. Most 3W generators will happily run two headlights in series, including (all?) shimano 3W models.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

De Sisti
Posts: 778
Joined: 17 Jun 2007, 6:03pm

Re: Hub Dynamo for winter commute.

Postby De Sisti » 6 Jan 2020, 9:00pm

zenitb wrote:
niggle wrote:Just discovered a new offering from Shimano claiming up to 44% reduction in dynamo drag: https://www.spacycles.co.uk/m2b0s133p43 ... H-UR700-3D

good spot niggle..looks v.interesting..

Does that make it 56% efficient? The SON dynamo claims 65% efficiency .

https://www.google.com/search?q=how+eff ... e&ie=UTF-8
The efficiency of the SON is quoted by the manufacturers at 65% (so just over 5 W of the rider's output is diverted to produce 3 W of electrical power) but this applies at only 15 km/h (10 mph). At higher speeds the efficiency falls.

Brucey
Posts: 36851
Joined: 4 Jan 2012, 6:25pm

Re: Hub Dynamo for winter commute.

Postby Brucey » 6 Jan 2020, 9:02pm

niggle wrote:Just discovered a new offering from Shimano claiming up to 44% reduction in dynamo drag: https://www.spacycles.co.uk/m2b0s133p43 ... H-UR700-3D


DH-UR700-3D is claimed to be up to 44% less draggy than DH-T8000. However since we don't know what the drag is on DH-T8000, or whether it is the difference of ~0.5W parasitic drag when the lights are off at a walking pace or something, we're not that much better off for knowing it.

FWIW I thought DH-T8000 had innards similar to DH-3N80; if so, that is already a generator with very low drag.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Greystoke
Posts: 222
Joined: 8 May 2018, 7:41am
Location: Lincolnshire

Re: Hub Dynamo for winter commute.

Postby Greystoke » 6 Jan 2020, 9:13pm

My Shimano dynohub runs 2 3w halogen lights in series, that's 12v 6w & has done on my daily commute for ages

nichog
Posts: 13
Joined: 2 Jan 2013, 11:52pm

Re: Hub Dynamo for winter commute.

Postby nichog » 6 Jan 2020, 9:47pm

Whatever set up you use the freedom from having to worry about charging batteries is well worth it.
One tip though is always carry a head torch or similar in case of breakdowns. I was lucky the other day that a passing cyclist stopped and gave me enough light to fix a detached wire on my dynamo plug in the middle of unlit nowhere, otherwise it would have been a very dodgy ride back to suburbia. A puncture would have been similarly difficult..


I'm a trendy consumer. Just look at my stupid phone.

steelframe
Posts: 42
Joined: 3 Aug 2015, 10:02pm
Location: Berlin

Re: Hub Dynamo for winter commute.

Postby steelframe » 6 Jan 2020, 9:58pm



Ah, thanks! So it is a forum post from 2005, referring to and quoting results from a test made in 2004. the person who did the test is Andreas Oehler who has and still is working for Schmidt. He is highly qualified, his tests are (despite him working for Schmidt) absolutely neutral and I consider them the best ones you can get in that field. I know him personally and consider him to be a person of highest integrity. The extended version of that test was published in Fahrradzukunft, a German non-profit bike-magazine with a very good reputation. You can find it online here, Google translate may help to convert it to English:
https://fahrradzukunft.de/1/labortest-nabendynamos/

It is worth mentioning that the Shimano 3N30 seems not to be mentioned in the final test report and - with the test being more than 15 years old - Schmidt has released several new models of the SON since then plus the SON XS that took part in the test was a prototype preproduction model and ran out of competition. So today you have to be a bit carefull with interpretation of results for "the SON" as today there are way more models than back then. I did not compare your qutoted results from the forum post to the article in Fahrradzukunft - possible that you may find some differences.

There is also a newer version of the test made in 2012 with some additional models including the SP SV8, you can find it here:
https://fahrradzukunft.de/14/neue-nabendynamos-im-test/

steelframe
Posts: 42
Joined: 3 Aug 2015, 10:02pm
Location: Berlin

Re: Hub Dynamo for winter commute.

Postby steelframe » 6 Jan 2020, 10:02pm

nichog wrote:Whatever set up you use the freedom from having to worry about charging batteries is well worth it.
One tip though is always carry a head torch or similar in case of breakdowns. I was lucky the other day that a passing cyclist stopped and gave me enough light to fix a detached wire on my dynamo plug in the middle of unlit nowhere, otherwise it would have been a very dodgy ride back to suburbia. A puncture would have been similarly difficult..


I'm a trendy consumer. Just look at my stupid phone.


With the SON you will (in opposite to most other dynamos) having a hard time to detach a wire by accident. And in case of trouble with a puncture the stupid phone from your bottomline probably has a torch built in. :)

pwa
Posts: 11302
Joined: 2 Oct 2011, 8:55pm

Re: Hub Dynamo for winter commute.

Postby pwa » 6 Jan 2020, 10:05pm

steelframe wrote:
nichog wrote:Whatever set up you use the freedom from having to worry about charging batteries is well worth it.
One tip though is always carry a head torch or similar in case of breakdowns. I was lucky the other day that a passing cyclist stopped and gave me enough light to fix a detached wire on my dynamo plug in the middle of unlit nowhere, otherwise it would have been a very dodgy ride back to suburbia. A puncture would have been similarly difficult..


I'm a trendy consumer. Just look at my stupid phone.


With the SON you will (in opposite to most other dynamos) having a hard time to detach a wire by accident. And in case of trouble with a puncture the stupid phone from your bottomline probably has a torch built in. :)

Holding the phone in your gob to keep your hands free? It requires the smallest of torches in your kit bag to cover all eventualities.

steelframe
Posts: 42
Joined: 3 Aug 2015, 10:02pm
Location: Berlin

Re: Hub Dynamo for winter commute.

Postby steelframe » 6 Jan 2020, 10:15pm

pwa wrote:I see the Schmidt hubs as the best you can get, and the difference in cost isn't much if you expect to get a good few years of use out of it. That's how I assess cost. Cost per commuting year. (...) I would happily spend more on components that promise a long service life. Just looking at Spa's offerings, choosing a Schmidt rather than an SP will add £90 to the cost of a wheel, which is a lot. But you could be looking down and seeing that Schmidt for a decade, at £9 per year premium.

Couldn't agree more! Furthermore: Owning a couple of different SON dynamos, two different Shimano dynamos and a SP SV9 I can say that until now none of those let me down until now. I do however know a couple of Brompton-Shimanos that broke. And from my personal experience the Shimanos do produce recognizably more drag than the SONs or the SP. The latter two seem to be more or less equal in terms of drag - at least I cannot feel a difference. Measuring could however show some. Still I consider the SON to be of higher quality (including the fact relevant for winter commute which is the thread topic that the SON has a built in breathing/drainage system at the axle that ist especially useful when a bike is used in heavy winter).
Thus for a bike that I want to rely on on a daily basis for years after years I'd always pay the premium for the SON as longterm the difference in price becomes totally irrelevant while reliability is not. With cheaper Shimano-models and some bad luck you may even end up more expensive than with the SON if you have to replace it, possibly even more than once (happened to a couple of Brompton owners). If I was tight on budget I'd go for one of the SPs as they - in my opinion - roll way better than the Shimanos I know.

Brucey
Posts: 36851
Joined: 4 Jan 2012, 6:25pm

Re: Hub Dynamo for winter commute.

Postby Brucey » 7 Jan 2020, 12:14am

I don't doubt the tester's integrity per se but I would expect them to have tested the hubs in the 'as received' condition, unless stated otherwise. IME this flatters many cartridge bearing hubs and does the reverse for cup and cone hubs.

When a wheel is built the hubshell sees some pretty large loads that don't exist when the hub is just a hub. These loads stretch flanges radially and also bring them closer together. This changes the preload in cartridge bearing hubs (often they end up with more axial preload than is normal) and also changes the adjustment in cup and cone bearings.

IME shimano hub generators are supplied in such a state that the LH cone usually needs backing out about 1/4 turn in a built wheel. In a loose hub it is even more than that. Also the seals are quite draggy when new, because they are still tight and they often don't have enough (good) grease on them either.

This means that the drag figures measured in such tests are not necessarily representative of those that you will see in practice. I often check the 'lights off' drag when I've built the wheel by simply spinning the wheel and noting how long it takes to slow down. By simply greasing the hub bearings and seals properly, and adjusting the bearings correctly, I usually find that the 'lights off' drag is about halved on a new shimano hub. Probably there is more to come, too, once the seals (which are full contact seals, unlike those in most cartridge bearings, yes even 2RS ones) have 'run in' properly.

So I'd suggest that the measured drag on shimano hubs in such tests should be regarded as a 'worst case' result, and doesn't represent what you will see in practice if you simply adjust the bearings correctly and give the seals a squirt of lube (even aerosol SFG). This will only take about two minutes to do, so is hardly an unreasonable expectation or anything...

There have been some pretty draggy generators produced (including some which drag more with the lights off than on) but for the reasons above I would suppose that a correctly set up shimano sport series hub is both more efficient and less draggy ( esp with the lights off) than test data suggests.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
interestedcp
Posts: 308
Joined: 5 Jan 2012, 3:34pm

Re: Hub Dynamo for winter commute.

Postby interestedcp » 7 Jan 2020, 2:13am

steelframe wrote: I do however know a couple of Brompton-Shimanos that broke.


They were probably Shimano DH-F703 Capreo dynamo hubs. These hubs are cheap entry level hubs that are far from having the high quality bearings and build quality as the high end Shimano dynamo hubs like the Shimano 3N72.

All the Shimano high quality dynamo hubs have outstanding borazon polished bearing races. After around 7 years of use I couldn't even see the usual bearing grooves in the bearing races on my Shimano 3N80. It is still going strong 11 years after I purchased it.
In my opinion the Shimano cup-and-cone bearings (12 or 13x3/16" balls) are superior to any SON or SP cartridge bearing.

steelframe wrote: And from my personal experience the Shimanos do produce recognizably more drag than the SONs or the SP.


It really isn't possible to discern any difference in drag from the high end Shimano, SON or SP dynamo hubs just by riding them. At 30 km/h the difference in drag between a new SON28 and a Shimano 3N80 is around 1 watt. The Shimano 3N80 and SP PV-8 have practically identical drag at 30 km/h.
The Shimano hub must have been a really low-end, badly adjusted hub if you could feel the difference.

In my experience the high end Shimano dynamo hubs are very well designed and are extremely reliable. They are the only lightweight dynamo hubs that can be serviced without taking the wheel apart, and they have readily availably spare parts for everything but the hub shell.

I have now serviced the bearings on my oldest Shimano dynamo hub (3N80) twice in 11 years and expect it to run for several years before another bearing service is needed. Lots of grease and the trifling cost of 26 pieces of 3/16" grade 25 ball bearings have been the only expense in all that time.

I don't doubt SON dynamo hubs are good, but don't look down on Shimano dynamo hubs. The Shimano 3N80, 3N72 etc. really are good hubs, that when it comes to price and DIY serviceability are better than SON and SP hubs, and practically identical in electric performance and drag.
--
Regards

steelframe
Posts: 42
Joined: 3 Aug 2015, 10:02pm
Location: Berlin

Re: Hub Dynamo for winter commute.

Postby steelframe » 7 Jan 2020, 7:31am

Brucey wrote:I
IME shimano hub generators are supplied in such a state that the LH cone usually needs backing out about 1/4 turn in a built wheel. In a loose hub it is even more than that. Also the seals are quite draggy when new, because they are still tight and they often don't have enough (good) grease on them either.

Fair statement. The question is which state is more relevant for "the user". A mechanically interested and qualified bike-hobbyist may do the helpful modifications and necessary tuning steps to a Shimano hub whereas an ordinary user neither will nor is able or willing to perform them. And probably neither bike manufacturers nor most bike shops will do this as well. So it would probably be interesting to measure both states of a Shimano hub: tuned and untuned. But generally I would consider the untuned state to be more relevant for most users. And a shame that Shimano is either not willing or unable to deliver their hubs in a well performing state.

steelframe
Posts: 42
Joined: 3 Aug 2015, 10:02pm
Location: Berlin

Re: Hub Dynamo for winter commute.

Postby steelframe » 7 Jan 2020, 7:51am

interestedcp wrote:They were probably Shimano DH-F703 Capreo dynamo hubs. These hubs are cheap entry level hubs that are far from having the high quality bearings and build quality as the high end Shimano dynamo hubs like the Shimano 3N72.


Jup. Still it was since 2010 until last year the default hub dynamo delivered by Brompton if you did not go the upgrade path for the SON (heavily overpriced if you ordered it from Brompton) or went for a SON aftermarket way cheaper or the uncomfortable route for an SP (only available for a couple of years now and not too easy to get hold of the Brompton model, the more as a prebuilt wheel). And as the Shimano was not cheap either the price-step to the SP was quite minimal and the step to the aftermarket SON recognizable but worth it.

All the Shimano high quality dynamo hubs have outstanding borazon polished bearing races. After around 7 years of use I couldn't even see the usual bearing grooves in the bearing races on my Shimano 3N80. It is still going strong 11 years after I purchased it.
In my opinion the Shimano cup-and-cone bearings (12 or 13x3/16" balls) are superior to any SON or SP cartridge bearing.

interestedcp wrote:The Shimano hub must have been a really low-end, badly adjusted hub if you could feel the difference.

One was indeed the Capreo Brompton model (where the difference is really obvious when riding), the other one is a mid-to upper range Shimano in a 20" wheel where it was not that obvious but still recognizable.

interestedcp wrote: They are the only lightweight dynamo hubs that can be serviced without taking the wheel apart, and they have readily availably spare parts for everything but the hub shell.

Just that they seem to be not that lightweight in comparison to others as far as I'm informed and with the SON you typically do not need spare parts and if - after ages - still something goes wrong they rebuild it for you at the manufacturer for a cheap price. Still totally fair if you prefer the Shimanos (as I prefer the SONs).
interestedcp wrote:I have now serviced the bearings on my oldest Shimano dynamo hub (3N80) twice in 11 years and expect it to run for several years before another bearing service is needed. Lots of grease and the trifling cost of 26 pieces of 3/16" grade 25 ball bearings have been the only expense in all that time.

My oldest SON dates from 2002 and is still going strong (as do all the others). Absolutely no need to even look for the bearings. That is the strong side of the SON: Total nobrainer, fire and forget.

interestedcp wrote:I don't doubt SON dynamo hubs are good, but don't look down on Shimano dynamo hubs. The Shimano 3N80, 3N72 etc. really are good hubs, that when it comes to price and DIY serviceability are better than SON and SP hubs, and practically identical in electric performance and drag.

Price in comparison to SON yes, in comparison to SP not so much. Price/value may be a totally different story, depending from the individual opinion. Electrical performance: Yes, more or less. Drag: in my opinion no. DYI servicabiliy: If you consider this to be an advantage depends for one from your willingness and abilities to perform such a service and secondly I still consider it better if no service is necessary anyway. Things like the air-system in the SONs are still a total USP and were invented I think in the early 2000s after corrosion with very early models of the SON that lacked that in harsher conditions (caused by daily massive temperature change indoor/outdoor in winter combined with wet weather and sometimes freezing temperature), so due to a real world problem. 20 years later as to my knowledge still no other manufacturer offers something similar. So to me the SON is still the best dynamo and possibly as good as it can get - knowing Wilfried Schmidt (owner of the SON "factory") very loosely I know that he is totally dedicated to quality plus he has a really cool, fair and great small company that I prefer to support compared to a huge giant like Shimano.