Which hub dynamo

[andrew549]

I'm looking at getting a new dynamo for my winter bike as I do quite a bit of night riding as well as commuting. I've been looking at the offerings from shimano, shutter precision and Son but not sure which to go for or if there are any other hubs I should be looking at. In terms of budget I don't mind paying more if it's noticeably better.

Thanks for any advice
Andy

[pete75]

I have Shimano DH30, DH72, DH80 and Son 28 on different bikes. They are, for all practical purposes identical in performance, none has any noticeable drag and all provide equally good lighting at anything above walking pace. If you ride very, very slowly get the Son otherwise any of the Shimano offerings will do.

[Heltor Chasca]

SHIMANO Deore XT DH-T785-1D Disc hub dynamo for me from Rose. Lights and USB too. Good price in my opinion. Happy shopping...b

[Rich_Clements]

Happy Shimano user here, not tried the rest but mine works

[seph]

another happy shimano user. Mine has been faultess for 6 years now, it's well into its second rim.
One time I rode with it fully immersed in a flood for over half a mile, the lights never went out!

I was happy to rely on it through Paris Brest earlier this year too.

Mine is the now superseded DH3N72, The DH3N80 should be better.

[andrew_s]

The small wheel hubs (Sondelux and Shutter Precision SV and SD) give a bit less drag an a bit less power. The less power doesn't affect lights unless you are going pretty slowly, but may make a noticeable difference if you want to use the hub to charge things.

In Shimano speak the (rare) 1N and 2N hubs are a nominal 1.5W and 2.4W respectively. Everything else is 3W nominal.The 3N20 and 3N30 hubs are commuter grade, with more drag and less good bearings (but perfectly usable if you are on a budget). The 3N72, 3N80, T785 etc all have the same innards and give the same performance, so you differentiate on weight and expected groupset level as for anything else.

Warranty is 1 year for Shimano, 2 years for Shutter Precision, and 5 years for SON.

My 1998 SON was still going strong when it's 5th rim was declared worn out about 6 months ago. I'm still considering whether to send it back for an overhaul (I'm using another anyway). It's been ridden through wheel-deep floods more than once too.

[PH]

My 1998 SON was still going strong when it's 5th rim was declared worn out about 6 months ago. I'm still considering whether to send it back for an overhaul (I'm using another anyway). It's been ridden through wheel-deep floods more than once too.

That beats my 2001 and 2004 SON hubs, both still working fine, neither on the original bike.
Unlike the Shimano offerings, the silver ones also polish up like new (I'm assuming the modern version is the same?)

[jacksonz]

I've had two Shimano dynamos that I used for heavy weight touring. The bearings on the first one became badly pitted after approximately 10,000km. I replaced it with an XT version that lasted about 5,000km. The plastic former in the stator developed a split that caused the stator to hit the magnets on rotation. Eventually a piece of lamellation broke off and made a constant ratcheting noise against the magnets! Junk! Recently I purchased a SON. I haven't been far on it yet.

It is certainly important to adjust the bearings carefully on a new Shimano, the factory seems to neglect this. The Shimano hubs are in general non-serviceable, however with some knowledge and difficulty it is possible to service both bearings. I found it impossible to get new cones at a decent price. Personally, I am fed up with Shimano hubs (of any kind) and will only buy hubs with cartridge bearings.

[Brucey]

If the bearings become pitted inside 50000 km (leave alone 5000 km) then there are only three reasons for this

1) water got inside and the grease didn't cope or

2) the bearings were not adjusted correctly, or

3) the parts are made badly.

In shimano hub generators the only ones with badly made bearings (that I know of) have been DH-3N71 models, where it was a design issue. Even then the bearings need to be badly adjusted to break up in short order. The factory bearing adjustment is not adequate, but then how could it ever be? - the bearing adjustment always varies once the hub is built into a wheel. The correct adjustment is a little free play that just disappears as the QR is fully tightened. That water can get into these hubs is well-known and I have seen several where the insides are horribly corroded. The shimano bearing grease is sparsely applied and anyway does not resist corrosion very well, and in a UK winter it is quickly overwhelmed. Any hub generator with a trapped airspace can go bad; even SON hubs with the latest breather design can corrode internally; it just seems less common than with other hubs.

[FWIW you can easily service a shimano LH bearing; the RH bearing can have fresh grease added to it without overwhelming difficulty; normally there is enough wiggle room to add fresh lube via a thin plastic tube. If you do this twice a year and use good quality grease (with corrosion inhibitors etc) the hub bearings should last OK.]

The real killers for water ingress are

1) taking the bike out into cold rain from warm storage (or similar); the air inside the hub contracts and then the water gets sucked inside (quite likely with several shimano designs, but they are certainly not alone in this).

2) condensation. Any time there is 100% humidity and the temperature then drops, you will get some condensation inside the hub. I think this is what can finish off even the best hub generators.

If I had two hubs of any kind fail in a couple of year's use I'd go off them for sure. However to therefore conclude that all cup and cone bearings are terrible and that all cartridge bearings are wonderful is not sensible IMHO. Hub generators with cartridge bearings are no easier to service (in fact they are usually worse) than those with cup and cone bearings; it is hopefully a less frequent requirement with some, but then it jolly well should be, given the cost.

Note that SON hubs (and some others) operate with a 'return to base' warranty (5 years for a SON, I think) whereby in the event of trouble you have to dismantle the wheel, ship the hub (to Germany, or approved national agent) and then rebuild it at your cost. I think this is only acceptable if the chances of failure inside a reasonable lifetime are small (which does appear to be the case). If you have the hub serviced voluntarily you pay shipping, wheel building, and service costs. The service costs alone are comparable to the price of an inexpensive hub generator.

Shimano hub generators have a two-year warranty, so things like a cracked stator shouldn't be a real concern, (unless shimano choose to try and duck out of it because (say) there is some corrosion inside as well, and they claim this is somehow your fault). In the vast majority of instances in the event of major troubles, you can simply replace the internal parts of a shimano hub generator and the hub will be back in top condition. You can do this without rebuilding the wheel and the cost of the parts is the same as buying a spare hub (so about £20 to £50) because this is where they should come from . The only mechanical parts that are retained are the hubshell/magnets and the LH bearing cup. Neither are likely to fail.

More recent shimano designs seem to use double seals; this seems to be an improvement; e.g. some users report many years of service from DH-3N80 models so these are certainly a viable choice, provided they are adjusted correctly to start with. If you regrease and adjust at intervals (shorter than with other shimano hubs) almost any shimano hub generator can have bearings that last well.

By contrast the SON hubs are more of a fit and forget solution; you are certainly in a world of pain in the event of problems, but there is a warranty, and the chances of such trouble are slight.

cheers

[samsbike]

I have the shimano hub and had it built up by Rose.

I can't complain in that it works well and compared to the SON is cheaper.

If the bike is just a commuter I would get the shimano and to be honest, unless you really fancied the bling, I would still get shimano for the best bike.

Also consider getting the disc hub even if you run caliper brakes as if you do get a disc bike later, you have the hub.

The only bit to be careful about is that I don't think you can convert the QRs to a through axle that some of the disc bikes are now using.

[NUKe]

I have 2 Shimano ones
A DH3N80 purchased 5 years ago about to go into its 6th winter 37,000 miles, still as good as new
A DH3N30 about 4 years old, this is on the bike that gets used for shopping trips to the pub or takes over the commute when the weather is too bad for the other. No idea of miles but probably around 10k

Both dynamos are still in good condition , bearing fines run faultless

[old_windbag]

As others have put forward Rosebikes are a good starting point to look for either the dyno hub or fully built wheel/wheelsets. I got a fully built Mavic A319 rim, DB stainless spokes and Shimano 3N80 dynamo for £63! eighteen months ago. Prices constantly change but even recently they had a full wheelset F+R with 3N80 for around £120. They are easy to deal with via email and I found they were willing to modify a stocked item or make up a custom wheel choice and would generate a price for it. They have an excellent range of dyno hubs, wheel rims and lights all at very low prices ( sign up for their email newsletter and get 10 euros off the order... I find this covers shipping ). Some of the wheelsets also come with tyres and tubes.... quality tyres too.

[andrew549]

Thanks for the replies, I've currently got 2 of the shimano 3d80 in a couple wheels only had them for about a year and was wanting to see if there was any reason to switch to one of the more expensive models.

The bike is going to be used mainly for long rides of around 200km+ or so along with a bit of commuting so was wandering if the better efficiency of the other hubs was worth it compared to shimanos offerings.

Has anyone used any of the shutter precision offerings as they seem to have the best of both worlds with much lower cost than the Son and apparently more efficient than shimano but I can't seem to find many reviews of them

[Brucey]

in BQ they reviewed a few hub generators a few years ago and they also did some sums regarding the change in speed as a result of the hub generator drag.

On-load, a DH-3N80 is about the same efficiency as other hub generators; the actual efficiency varies with the nature of the load and the speed, so select your data with care!

Off-load there is almost 1W more drag than a SON and 1.5 to 2W more drag than a normal hub.

Because of the effect of air resistance, even if this is 1% of your power output, it won't make 1% difference in speed, it'll be less than that.

Even rather poor hub generators are not terribly inefficient when on load, so there might be ~2W variation between the best and the worst at about 20mph with a 3W output.

If you are worried about drag, then worry about the 5-6W that the hub generator causes when the lights are on. This might make 0.3 to 0.5mph difference.... but I'd sooner put up with that than the faff of batteries!

cheers

[old_windbag]

There are two articles that may be good to read, one I think is the one Brucey is talking about.

If the links work they are worth reading.

http://www.ctc.org.uk/file/public/feature-hub-dynamos.pdf

http://www.bikequarterly.com/VBQgenerator.html

the BQ one is also available as a PDF file if you search for it.