Hub Dynamo for winter commute.

[bgnukem]

Having used both systems, I like the low weight and looks of the SP dynohub but find that it cuts the light at lower speeds than the Shimano hubs (have had both 3N71 and 3N80), which can be an issue manoeuvring at low speeds in winter, e.g. making a U-turn on unlit lanes. My commuter has 26" wheels too so on a 700c-wheeled bike you'd have to be going faster to fire up the front lights.

I suspect I might buy another Shimano dynohub next time, but have to admit to wrecking one trying to loosen the cone on the 'wire side' to get some grease into the bearing. After loosening both cones nothing I could do would get the hub to rotate properly again and in loosening and tightening the cone multiple times I assume I broke the wire.

With the non-wire-side cone loosened there's a small gap on the wire side so next time I might just blow some spray grease into that bearing using the straw on a spray can. It's not great but better than running the bearings dry and/or dirty as there was little evidence of grease in the bearings after a couple of winter's use. Why Shimano don't use sealed cartridge bearings in their dynohubs is beyond me...

[Brucey]

....With the non-wire-side cone loosened there's a small gap on the wire side so next time I might just blow some spray grease into that bearing using the straw on a spray can. It's not great but better than running the bearings dry and/or dirty as there was little evidence of grease in the bearings after a couple of winter's use...

I think that sort of approach is the best balance between risk and benefit for most folk. However my suggested approach is to use a thin-walled flexible (squashable) tube to introduce grease using a nozzle-type grease gun. You only need a gap about 1mm wide this way; thinner than any straw on an aerosol and you will get more grease in that way too. You can make more space by backing out the RH cone a turn or so; the generator can usually be run like this without detriment (there is a fair clearance both sides between the workings and the hubshell) and this confers very little risk to the wire etc.

A good part of the fundamental problem is that shimano don't put much grease in the bearings to start with; what there is, is notably lacking in corrosion inhibitors and doesn't have the kinds of additives that are of real benefit in low-speed bearings (such as solid lubricants) either. The grease that you put in can be considerably better than this.

Why Shimano don't use sealed cartridge bearings in their dynohubs is beyond me.

Well you would still have the same problems when the bearings need attention, more or less, unless the connector assembly could pass undisturbed through the RH bearing (as discussed elsewhere). FWIW the seals on cartridge bearings are not that good; arguably the (double) seals on 'sport series' shimano hub dynamos are far better designed.

Part of the trouble with almost all hub generators is the fresh air inside them; this expands and contracts with temperature changes and condensation can form inside the hubshell without much difficulty too. SON's pressure compensation system is a very great help but it does not solve the problem entirely. However without it, most hub generators simply 'breathe' through the hub bearings. Sometimes they 'breathe in' water and worse still they can breathe in water that is contaminated with road salt. This sees off the bearings in short order; only the most robustly fortified greases resist this kind of corrosive attack.

FWIW I have recently carried out a straw poll of cartridge bearings that have been routinely replaced at an LBS near me. Some are (rightly or wrongly) replaced as a precautionary measure, others start to feel slightly rough and are replaced, others yet fail entirely (very badly worn and corroded inside, or seize up through corrosion... ) and only then are they replaced.

The conclusion is that -almost without exception- the bearings that get replaced (including those that seem just fine) have sod-all grease inside them. In most cases even if there is no corrosion inside, there is so little grease inside the bearing that you cannot say with confidence what colour the original grease was, even.... I think that in most cases this happens because there wasn't enough grease in there to start with. In a few cases there may have been enough grease to start with but it has escaped, degraded separated, or been displaced somehow. In a typical hub generator the 'breathing through the bearings' will definitely displace or degrade the kinds of grease that I have seen in such bearings.

cheers

[andrew_s]

There are 2 types of SP dynohub - the SD8 or SV8 (disc and rim brake), and PD8 or PV8

The S?8 models are the equivalent of the Sondelux, with fewer magnets for smaller wheels and lower rolling resistance, and give less power at low speed when used with a 700c wheel which spins slower at the same speed.

The P?8 models should be pretty much the same as the Shimano or SON28 as far as low speed light is concerned.
You'd also be better using one of these if you want to power gadgets via a USBwerk or Igaro.

[zenitb]

Decathlon offer the Shimano dynohub in both 700c and 26" wheels for an amazing £29.99 - surely a low-risk introduction to dynamos.

That is an amazing price James.. little more than the hub price .. I am tempted to buy and hoard a spare dynowheel given I have a Decathlon store down the road.

On my old commuter bike I already have the Taylor Wheels 3N31/Ryde Zac 2000 wheel (in 26" form - bought for £40) and this has done 3yrs = 10,000 miles of bumpy towpath/rough tarmac commute with no issues at all. I only took it off the bike recently because I had built a new SP Dynamo wheel and wanted to rest the 3N31 and take it apart .. to check the bearings (carefully - following advice from this forum - obviously !!! )

One difference between the Decathlon and my Taylor Wheels offering is that the Decathlon wheel appears to have an old style, budget, non-box section rim whereas the Zac 2000 rim on my Taylor Wheels wheel has a more modern box section rim (so potentially stronger ? - but £10 more expensive). Understandable at the price though and I take your point, that if you just wanted to try out a dynamo hub Decathlon are giving a very low risk route.

I think the OP wants to get a dynamo wheel built to a custom spec - which is sensible I guess. My first dynamo wheel was custom made for me by SJSC in the late '90s and its still true and working after 20 years on/off use (Shimano Inter-L hub). However you see lots of people berating dynohubs when you can see from their comments they have never even tried one .. the Decathlon wheel could be for them !!!

[Brucey]

FWIW I think that most single-wall rims are just fine on a front wheel. They lack stiffness for use in heavily dished rear wheels though.

cheers

[bgnukem]

There are 2 types of SP dynohub - the SD8 or SV8 (disc and rim brake), and PD8 or PV8

The S?8 models are the equivalent of the Sondelux, with fewer magnets for smaller wheels and lower rolling resistance, and give less power at low speed when used with a 700c wheel which spins slower at the same speed.

The P?8 models should be pretty much the same as the Shimano or SON28 as far as low speed light is concerned.
You'd also be better using one of these if you want to power gadgets via a USBwerk or Igaro.

I've got the PD8 disc dynohub on my 26" wheeled commuter but I note it takes a fair bit more speed to fire up the twin LED front light I'm using than the Shimano 3N71 I was using before, so I guess the SP hub has a lower power output, at least at low speeds.

[David9694]

This is a 20 mile round trip, right? I’m assuming all or part of it isn’t lit at all. I’ve lived in the countryside for 5 years and am still stick by how “dark” it when it’s dark.

Yours is an ambitious plan. On the ex railway track, you’re not too worried about following motor traffic seeing you, so you could consider running twin headlights from your dynohub wheel, which simplifies the wiring issue. Fiddly wires whose flimsy spade connectors can come detached from terminals I find are the main issue.

I run a SON 28 from SJS and have found it totally reliable over 5 years [Bruceyvwill tell me it needs to be serviced as the bearings are probably running on air). Check the German bike websites for the range of dynamo headlights you can get - they take these things very seriously there; none of this stuff comes cheap and I say that as someone who doesn’t go high-end normally because it’s only going to get broken, lost of stolen.

You might want to carry a battery light that has an LED strip light in case you have to do adjustments in the pitch black. As others have said, use battery or USB rear blinkers at the back and consider investing in a chunky, detachable USB front light - it helps if you’ve got access to a mains plug (and the right USB connectors) while you’re at work.

Take great care about pushing through puddles on the railway track - I would find an alternative way to travel if there are lots of whole width puddles - if you off in the dark, you get wet and at best it’s a miserable experience, dangerous at worst if you’re the only one mad enough to do be doing it. All that doom aside, it can be a lovely experience: catching am owl in your beam, the moon, the silence.

[Brucey]

I used to commute a similar distance and about half the route was offroad, out in the sticks, on a dirt road. It was pretty dark! When I started this run you could buy LED blinkies (just), HIDs were state of the art (for seeing with offroad) and halogen bulbs were a more affordable alternative. Hub dynamos with high power LEDs were not an option ( I had a hub dynamo that I used on a road bike, since the early 1980s, but it was old and feeble; nowhere near enough light for offroading, and newer ones such as SON were not yet built). I used High powered halogens (6 or 12W running light and 25W supplementary one for the gnarly bits which I couldn't run for long without draining the batteries too fast) on the handlebars and supplemented that with a head torch. I used a 6W plus LED blinkies on the road. I rarely met anyone coming the other way so I had no big worries about blinding oncomers. When it did happen I just turned off my high power lights until they had gone past.

However my life was a miserable one with charging batteries a daily chore, and reliability was extremely sub-optimal; I carried multiple rear LED lights and often got home to find that only one of three was still working. A few times all three main front lights conked out for various reasons and I had to ride the offroad stuff by the light of one feeble ('be seen', just...) LED blinky. It might give you an idea of how long ago this was because IIRC for a long time the front LED blinky was green, not white; white LEDs had yet to come to market....

These days I'd do that run with a hub dynamo and good LED lights, no worries. I'd carry a pair of LED blinkies as a backup and to see by to repair a puncture or whatever.

FWIW the worst visibility was when it was wet, but before things had dried out. In heavy rain, surfaces are wet and reflective; when they are merely damp they just absorb photons like they are going out of fashion and in addition there is less contrast between different surfaces than normal; everything on the ground was near enough the same shade of damp brown and everything not on the ground was about the same shade of damp dark green. Kind of tricky to see where you are going!

Note that lights on the handlebars allow you to see that there are holes ahead but not how deep they are; you just see a dark shadow and it isn't clear how deep the hole really is. This is Ok if you can always go around them, not so good if you cannot. The head torch helped me see how deep the holes were, but a fixed light that high wouldn't have let me see the holes so well to start with. I got to know every hole on my route...

cheers

[Steve O'C]

Encouraged by this thread and the fact that my front wheel rim has worn out I ordered the decathlon wheel and collected it yesterday.

https://www.decathlon.co.uk/28-front-hybrid-dynamo-wheel-id_8133890.html

Mine did come with a QR Skewer and the dynamo was the Nexus version.

As predicted by Brucey it was set up rather tight and with what looked like not much of the Shimano translucent green grease. I have added some more as suggested by loosening the left hand cone and gently pushing out the right side enough to inject some grease through a wide bore needle

This is my first dynamo hub and I did find it very difficult to set up the hub properly. Even when the bearings were obviously loose there was much more resistance to turning the axle than I am used to, a cog wheel resistance that i understand is normal for a dynamo hub.

As regards the rest of the wheel it was built with plain gauge spokes that I thought were a little loose. The rim was pinned and had a small ding in the surface but I guess it was good value. Total weight including the QR was 1677g

I am still not sure that I have adjusted the hub correctly.

[Brucey]

re the hub adjustment. Normally the correct adjustment of a QR hub is such that there is a little free play that just disappears when the QR is used to tighten the wheel in the frame. This usually works out that with the QR half-tight, you can still feel a little movement in the rim.

In practice a hub dynamo will usually tolerate a little more preload that this (because the hubshell is flexier) but shooting for the standard adjustment is unlikely to do any harm.

If you go back and readjust the hub so that the LH cone is backed out ~1/30th of a turn and there is free play with the QR tight, you will know that the adjustment was right before.

cheers

[SimonCelsa]

Another thumbs up (tentative) for the £29.99 Decathlon dynohub wheel.

Just received a 26" version, ordered online and delivered to a local ASDA as the nearest Decathon is a 3 hour drive away.

Nexus DH-C3000-3N-QR hub. Came with QR skewer despite contrary advice. Everything looks OK, wheel reasonably true, spokes feel OK, easy to add a bit more grease into the hub bearings.

I also ordered one of them plastic shimano plugs for the cables, thought this was a bit expensive at £3.50, however on receipt I see a bag of 10 was despatched!! Should see me good until I pop my clogs......anyone fancy a free connector just send me a PM & SAE, I should be able to spare half a dozen or so.

[SA_SA_SA]

[quote="bgnukem" ....With the non-wire-side cone loosened there's a small gap on the wire side so next time I might just blow some spray grease into that bearing using the straw on a spray can. It's not great but better than running the bearings dry and/or dirty as there was little evidence of grease in the bearings after a couple of winter's use...quote]

I think that sort of approach is the best balance between risk and benefit for most folk. However my suggested approach is to use a thin-walled flexible (squashable) tube to introduce grease using a nozzle-type grease gun. You only need a gap about 1mm wide this way;....[/quote]

Surely, it would be easy for Shimano to facilitate this with a 1mm (capped?) channel in the cone or somewhere?

[dim]

I've recently bought the SON28 and Supernova E3 Triple lights (front and rear) .... both the hub and the lights have a 5 year warranty

I commute daily when it's dark and get home when it's dark .... I will also be cycling Audax and touring, so I did not mind spending the additional money

The Supernova front light is very bright and makes the night look like day, so if you are cycling on roads with lots of cyclists heading towards you, you need to tilt the front light down .... for my rear backup light, I use the Cygolite Hotshot Pro 200 ... an amazing bright back light with 8 hrs of runtime ...

for the front backup light, I will most probably buy the Cygolite Expilion 850 USB (9 hrs on low, and the low is very bright.... it also uses USB battery sticks, so you can buy these seperate for a long tour and carry as many as needed... I will use this light on my helmet)

If I were to spend a bit less, I'd most probably have bought a Shutter Precision dynamo hub and lights from Busch & Muller

[PH]

The Supernova front light is very bright and makes the night look like day, so if you are cycling on roads with lots of cyclists heading towards you, you need to tilt the front light down ....

You can't tilt it down far enough for it to not dazzle oncoming cyclists and drivers and it still be any use to you, that's why Supernova sell it as an off road light, that's why it isn't road compliant. Why didn't you get a road legal light? They're more than bright enough for on road use.

[dim]

The Supernova front light is very bright and makes the night look like day, so if you are cycling on roads with lots of cyclists heading towards you, you need to tilt the front light down ....

You can't tilt it down far enough for it to not dazzle oncoming cyclists and drivers and it still be any use to you, that's why Supernova sell it as an off road light, that's why it isn't road compliant. Why didn't you get a road legal light? They're more than bright enough for on road use.

I bought Supernova because I want a very bright front light .... I ride (fast) in the pitch dark on unlit roads with potholes and debris ....I am actually very glad that I bought this light, because it's a pleasure riding in the dark now ... when this light needs replacing in a few years time, I will buy the same